ex2000

gGE Industrial Systems

GEH-6375A

EX2000PWM Digital Regulator

User's Guide

gGE Industrial Systems

Document: GEH-6375AOriginal Issue Date: 1997-06-01Rev. A: 2000-07-20

EX2000PWM Digital Regulator

User's Guide

© 2000 General Electric Company, USA.All rights reserved.

Printed in the United States of America.

These instructions do not purport to cover all details or variations in equipment, nor toprovide every possible contingency to be met during installation, operation, andmaintenance. If further information is desired or if particular problems arise that are notcovered sufficiently for the purchaser�s purpose, the matter should be referred to GEIndustrial Systems, Salem, Virginia, USA.

This document contains proprietary information of General Electric Company, USA and isfurnished to its customer solely to assist that customer in the installation, testing,operation, and/or maintenance of the equipment described. This document shall not bereproduced in whole or in part nor shall its contents be disclosed to any third party withoutthe written approval of GE Industrial Systems.

Document Identification: GEH-6375, updated release

Windows NT is a registered trademark of the Miscrosoft Corporation.Windows is a registered trademark of the Microsfot Corporation.DIRECTO-MATIC is a registered trademark of the General Electric Company, USA.

GEH-6375A User's Guide Safety Symbol Legend •••• a

Safety Symbol Legend

Indicates a procedure, condition, or statement that, if notstrictly observed, could result in personal injury or death.

Indicates a procedure, condition, or statement that, if notstrictly observed, could result in damage to or destruction ofequipment.

Note Indicates an essential or important procedure, condition, or statement.

b •••• Safety Symbol Legend EX2000, PWM Digital Regulator GEH-6375A

This equipment contains a potential hazard of electric shockor burn. Only personnel who are adequately trained andthoroughly familiar with the equipment and the instructionsshould install, operate, or maintain this equipment.

Isolation of test equipment from the equipment under testpresents potential electrical hazards. If the test equipmentcannot be grounded to the equipment under test, the testequipment�s case must be shielded to prevent contact bypersonnel.

To minimize hazard of electrical shock or burn, approvedgrounding practices and procedures must be strictly followed.

To prevent personal injury or equipment damage caused byequipment malfunction, only adequately trained personnelshould modify any programmable machine.

GEH-6375A User's Guide Contents •••• i

Contents

Chapter 1 Overview 1-1Introduction ...................................................................................................................... 1-1System Overview.............................................................................................................. 1-2Product Overview ............................................................................................................. 1-3

Hardware Design ....................................................................................................... 1-3Power converter module............................................................................................. 1-5Software Design ........................................................................................................ 1-6Human-Machine Interface (HMI) ............................................................................... 1-8

Chapter 2 Hardware System Description 2-1Introduction ...................................................................................................................... 2-1Packaging......................................................................................................................... 2-2

Environmental ........................................................................................................... 2-2Enclosure................................................................................................................... 2-2

Ratings ............................................................................................................................. 2-3Input Ratings ............................................................................................................. 2-3Output Current Rating................................................................................................ 2-4Voltage Control Range............................................................................................... 2-4Power Profile Rating.................................................................................................. 2-4

Power Converter Hardware ............................................................................................... 2-5Ac and Dc Input Devices............................................................................................ 2-6Dc Link and Dynamic Discharge................................................................................ 2-6IGBT And IAXS Devices........................................................................................... 2-6Output Contactor MDA.............................................................................................. 2-7Output Shunt SHA ..................................................................................................... 2-7

Control Electronics Module .............................................................................................. 2-7TCCB (DS200TCCB) ................................................................................................ 2-8PSCD (IS200PSCD) .................................................................................................. 2-8GDDD (IS200GDDD) ............................................................................................... 2-8PTCT (DS200PTCT) ................................................................................................. 2-8NTB/3TB (531X305NTB) ......................................................................................... 2-9LTB (531X307LTB) .................................................................................................. 2-9RTBA (DS200RTBA)................................................................................................ 2-9ACNA (DS200ACNA) .............................................................................................. 2-9

Inputs and Outputs............................................................................................................ 2-9Generator Inputs ........................................................................................................ 2-94-20 mA Inputs.........................................................................................................2-10Generator Line Breaker Status...................................................................................2-10Generator Lock-Out Trip...........................................................................................2-10Additional I/O...........................................................................................................2-11

ii •••• Contents EX2000, PWM Regulator GEH-6375A

Chapter 3 Software System Overview 3-1Introduction ...................................................................................................................... 3-1Configuration Tools.......................................................................................................... 3-2Programmer Module ......................................................................................................... 3-2

Software Design ........................................................................................................ 3-2Standard Functions ........................................................................................................... 3-3

Automatic Voltage Regulator (AVR) Ramp................................................................ 3-3Automatic Voltage Regulator Setpoint ....................................................................... 3-3Automatic Voltage Regulator ..................................................................................... 3-3Field Regulator (FVR) Ramp ..................................................................................... 3-3Field Regulator .......................................................................................................... 3-3Under Excitation Limiter (UEL)................................................................................. 3-4Over Excitation Limiter (OEL)................................................................................... 3-4Firing Block............................................................................................................... 3-4

Chapter 4 Software Configuration and Scaling 4-1Introduction ...................................................................................................................... 4-1Configuration and Scaling Example .................................................................................. 4-2

Example Generator, Exciter, and Regulator ................................................................ 4-3General Configuration ...................................................................................................... 4-4Feedback Scaling.............................................................................................................. 4-6

Generator Feedback ................................................................................................... 4-6Bridge Voltage Feedback ........................................................................................... 4-7Bridge Current Feedback............................................................................................ 4-8Feedback Offsets........................................................................................................ 4-8Instantaneous Overcurrent Trip .................................................................................. 4-9

Regulator Scaling ............................................................................................................. 4-9Automatic Voltage Regulating System ....................................................................... 4-9Under Excitation Limiter (UEL)................................................................................4-13Reactive Current Compensator (RCC).......................................................................4-16VAR/Power Factor Control .......................................................................................4-17Field Regulator (FVR) ..............................................................................................4-18Field Current Regulator (FCR) ..................................................................................4-20

Optional Functions Scaling and Configuration..................................................................4-23Transducer Outputs...................................................................................................4-23Ground Detector and Diode Fault Monitor.................................................................4-24Field Thermal Model ................................................................................................4-25

Chapter 5 Startup Checks 5-1Introduction ...................................................................................................................... 5-1Prestart Checks ................................................................................................................. 5-2

Energization and Simulator Control Checks................................................................ 5-2Pre-start Power Checks ..................................................................................................... 5-4Initial Roll Offline Checks ................................................................................................ 5-6Online Checks .................................................................................................................. 5-7Operator Interface............................................................................................................. 5-8

Units with Innovation Series Controller ...................................................................... 5-8Units with Discrete Switches and Meters.................................................................... 5-8

GEH-6375A User's Guide Contents •••• iii

Chapter 6 Simulator Scaling and Operation 6-1Introduction ...................................................................................................................... 6-1Simulator.......................................................................................................................... 6-1

Simulator Scaling....................................................................................................... 6-2Operation................................................................................................................... 6-4

Glossary of Terms

Index

iv •••• Contents EX2000, PWM Regulator GEH-6375A

GEH-6375A User's Guide Chapter 1 Overview •••• 1-1

Chapter 1 Overview

IntroductionThis manual describes the EX2000 Pulse Width Modulated (PWM) digital regulatorfor brushless generator excitation systems. This is a microprocessor controlled powerconverter that produces controlled dc output for rotating exciter, brushless generatorapplications.

This manual is intended to assist applications and maintenance personnel inunderstanding the equipment hardware and software. It also provides initial startupinformation.

The manual is organized as follows:

Chapter 1 briefly defines the EX2000 PWM regulator with an overview of thehardware and software design. Includes references to other manuals and documents,one-lines and connection diagrams. Its purpose is to present a general productoverview for the reader as follows:

Section Page

System Overview ................................................................................................ 1-2Product Overview................................................................................................ 1-3

Hardware Design.......................................................................................... 1-3Power Converter Module.............................................................................. 1-5Software Design........................................................................................... 1-6Human-Machine Interface (HMI) ................................................................. 1-8

Chapter 2 Hardware System Description, contains specific information on systemhardware design and purpose, ratings, I/O definition.

Chapter 3 Software System Overview, contains specific information on softwaretools, structure, functions, and one-line representations.

Chapter 4 Software Configuration and Scaling, gives examples of the scaling forspecific parameters in a generic brushless regulator generator application.

Chapter 5 Startup Checks, contains pre-start, startup, and on-line adjustmentsrequired during the commissioning of the PWM regulator for a brushless excitationsystem.

Chapter 6 Simulator Scaling and Operation gives example simulator scaling andoperation instructions for a typical brushless regulator generator application.

1-2 •••• Chapter 1 Overview EX2000, PWM Digital Regulator GEH-6375A

System OverviewA second power source is alsopossible from a dc batterysource.

The PWM regulator controls the ac terminal voltage and/or the reactive volt amperesof the generator by controlling the field of the rotating brushless exciter. Figure 1-1shows a typical one-line system of a Permanent Magnet Generator (PMG) fedbrushless generator application. Power for the regulator is normally supplied from aPMG driven directly by the main generator field. This can be a single phase or 3-phase PMG. An alternative method is to obtain excitation regulator power from aPower Potential Transformer (PPT) supplied from an auxiliary bus. This can also bea single or 3-phase supply. The PPT is required to ensure an ungrounded input to theregulator.

The control system contains both a generator terminal voltage regulator and anexciter field current regulator. These are known as the automatic or ac regulator andthe manual or dc regulator respectively.

When operating under control of the dc regulator, a constant exciter field current ismaintained, regardless of the operating conditions on the generator terminals. Whenoperating under control of the ac regulator, a constant generator terminal voltage ismaintained under varying load conditions. If the generator is connected to a largesystem through a low impedance tie, the generator cannot change the system voltageappreciably. The ac regulator, with very small variations in terminal voltage, thencontrols the reactive volt amperes (Var)s.

If the generator is isolated from a system, the ac regulator controls the terminalvoltage and the Vars are determined by the load. Most systems operate in a mannerthat is between these two extremes. That is, both Vars and volts are controlled by theac regulator. Normal operation is with the ac regulator in control, with an automatictransfer to the dc regulator in the event of loss of potential transformer feedback asdetected through Potential Transformer Failure (PTFD) or PT UndervoltageDetection (PTUV).

In the regulator, PT Failure Detection requires two sets of PT inputs. There isautomatic tracking between the ac and dc regulators to ensure a bumpless transfer ineither direction. A balance signal is available for display on the operator station orturbine control interface. A transfer between regulators can be initiated by theoperator or, if supplied, by the PT failure detection algorithm. In addition to thereference input to the ac regulator summing junction, a number of both standard andoptional inputs are possible.

The regulator includes aLocal Area Network (LAN)and RS-232C interfaces forexternal communication.

Besides the regulating functions, the excitation system contains protective limiterfunctions, startup and shutdown functions, and operator interfaces that areimplemented in both hardware and/or software.

The software is accessed via an RS-232C communication link using the GE ControlsSystems Toolbox (toolbox). The toolbox is used to configure and maintain regulatorsand exciters. It is Windows -based and consists of a collection of programs (tools)running under a command shell.


Figure 1-1. PMG Brushless Exciter Overview

Product Overview

Hardware DesignOptional hardware devicesare also available, such as 4-20 mA transducers, PPT, andField Ground Detector Powersupplies.

The regulator hardware consists of a control core and a power converter section,described in Chapter 2. The controller includes printed wiring boards containingprogrammable microprocessors with companion circuitry, including electrically-erasable programmable read-only memory (EEPROM) where the regulator�s systemblockware pattern is stored. The power converter consists of input disconnects andfilters, a dc link with charge control, IGBT devices, output contactor and shunt, andcontrol circuitry.


Control Core (Regulator Module)Refer to figures 2-3 and 2-4in Chapter 2.

The control core is mounted in two board racks on the outside of the core panel andis accessible while the regulator is operating. Also, behind the hinged outer door,several Input/Output (I/O) boards are mounted. The control core consists of all thesecircuit boards interconnected by ribbon cables and harnesses, which keep wiring to aminimum. Detailed hardware information including fuse and test point information,replacement instructions and board layouts are provided in the referenced documentsfor each of the following circuit boards.

Power Supply and Contactor Driver (PSCD) board creates internal power suppliesand redistributes the necessary power supply voltages for the other control corecircuit boards. An isolated 70 V dc supply is also produced and used for LTB boardinputs. The PSCD board also produces the contactor coil voltage for the MDA outputand charge control contactor (refer to GEI�100241).

Gate Driver and Dynamic Discharge (GDDD) controls the gating of the IGBTs forbridge output and Dynamic Discharge control. It also isolates and scales dc output,dc link voltage, shunt feedback and heat sink temperature feedbacks (refer to GEI�100240).

LAN Terminal Board (LTB) provides an interface between control devices andexternal devices such as contactors, relays, indicators, lights, pushbuttons andinterlocks (refer to GEI−100022).

Microprocessor Application Board (TCCB) contains software transduceringalgorithms that mathematically manipulate the inputs from the isolation and scalingprinted wiring boards. These inputs are analog feedback signals from the current andvoltage transformers, which monitor generator output and line voltage, and from thebridge ac input and dc output voltages and shunt feedbacks (refer to GEI−100163).

I/O Terminal Board (NTB/3TB) includes an RS-232C communication port forconnecting to a personal computer (PC). The optional field ground detector inputsare connected to the NTB board (refer to GEI�100020).

Drive Control and LAN Control Board (LDCC) controls LAN communicationand permits operator access and control via the Programmer keypad. It also containsthe drive control microprocessor which monitors start/stop sequencing, alarms, tripsand outer loop regulators and motor control microprocessors which monitors thefield voltage and current regulators, gating and overcurrent protection (refer to GEI�100216, for reprogramming the LDCC board refer to GEI−100217).

Relay Terminal Board (RTBA) provides seven output relays with form C contactsavailable for customer use which can be driven from a remote input or directly fromthe relays on the LTB board (refer GEI�100167).

ARCNET Link (ACNA) board provides the connection point for the ARCNETLAN communications.


Figure 1-2. EX2000 Brushless Unit

Power Converter ModuleThe power conversion section consists of an input section, a dc link, and theconverter output section. The input section is a 3-phase diode bridge with inputfilters. The range of the ac input is from 90 V rms up to 275 V rms. Frequency inputsrange as high as a nominal 360 Hz. It can be a single phase or three phase input froma PMG, auxiliary bus or generator terminal fed. An input PPT is not required for thePMG input. A PPT is required for an auxiliary bus or generator terminal feed. Anoptional voltage doubling feature is available for units requiring higher forcingcapability.

This circuit is normallypowered from the GDDDboard but may be poweredthrough the dynamicdischarge power sourceresistor RDS if control poweris lost.

An optional backup source from nominal 125 or 250 V dc batteries is filtered, diodeisolated and combined with the three-phase diode bridge output. These sourcescharge the power capacitors through a charge control resistor, RCH, which forms thedc link portion of the power converter module. The dc link is the unregulated sourcevoltage for the control core power supplies and the output power through the IGBTs.A coarse control of the voltage level of the dc link is provided by the dynamicdischarge circuit. This circuit will dissipate excess power from the dc link (possibledue to a regeneration effect from the field of the rotating exciter) through thedynamic discharge resistor, RDD.

The converter output section takes the dc link source voltage and pulse widthmodulates it through the IGBT devices. The output voltage is determined by thefollowing formula:Voutput = Vinput * (time on/(time on + time off))

For more information refer toChapter 5, Figure 5-1.

where Vinput is the dc link voltage, time-on is the conduction time of the IGBTdevices and time-off is the non-conduction time of the IGBTs. The choppingfrequency of the IGBTs is approximately 1000 Hz.

This output is fed to the rotating exciter field as a regulated voltage or current. Asingle pole contact from the MDA contactor isolates the regulator from the field. Anoutput shunt monitors the field current.


Optional Hardware ModulesScaling is provided in thePWM software.

There are a limited number of structured options available with the PWM regulator.Up to four 4-20 mA output transducers are available for customer use. They aredriven from D/A converters located on the NTB board, and are non-adjustabledevices.

A 50/60 Hz, 25 kVA Power Potential Transformer (PPT) is available for units thatare connected to an auxiliary bus or generator output terminals. This PPT may ormay not be supplied inside the regulator enclosure. Power to the primary should befused per the application notes found in the control elementary supplied with theequipment. This transformer is sized to supply rated excitation requirementscontinuously and still be capable of operation at ceiling excitation for a short time.

An optional Field Ground Detector Power supply may be supplied for some systems.This power supply provides 24 V control power to the Field monitor unit mounted inthe generator exciter housing. A 120 V ac feed is required to power this supply.

Software DesignThe regulator application software consists of modules (blocks) combined to createthe required system functionality. Block definitions and configuration parameters arestored in read-only memory (ROM), while variables are stored in random-accessmemory (RAM). Microprocessors execute the code.

Diagnostic software is transparent to the user. A programmer module with a digitaldisplay and keypad allows an operator to request parameter values and self-checks.

SoftwareThe exciter application emulates traditional analog controls. It uses an openarchitecture system, which uses a library of existing software blocks. The blocksindividually perform specific functions, such as logical AND gates, proportionalintegral (PI) regulators, function generators, and signal level detectors.

These blocks are tied together in a pattern to implement complex control functions.For example, a control function such as the under-excitation limit (UEL) is includedas an ac regulator input by setting software jumpers in EEPROM. The relevantblockware is enabled by pointing the block inputs to RAM locations where the inputsreside (the UEL requires megawatts, kilovolts and megavars). The UEL output isthen pointed to an input of the ac regulator summing junction. The software blocksare sequentially implemented by the block interpreter in an order and execution ratedefined in the toolbox.

The blockware can be interrogated while running by using the toolbox. Thedynamically changing I/O of each block can be observed in operation. Thistechnique is similar to tracing an analog signal by using a voltmeter.


AC and DC RegulatorsThe power system stabilizer(PSS) is an optional function.

The ac or automatic regulator and, dc or manual regulator are software functionsagain emulating traditional analog controls. The ac regulator reference is from astatic counter and is compared to the generator terminal voltage feedback to createan error signal. In addition to the reference signal input to the ac regulator summingjunction, the following inputs can be used to modify the regulator action.

Alternatively it can be used toprovide line dropcompensation.

Reactive Current Compensation (RCC): The generator voltage is allowed to varyin order to improve reactive volt amp (VA) sharing between generators connected inparallel. Generator voltage decreases as overexcited reactive current increases, andincreases as underexcited reactive current decreases.

Under-excitation Limit (UEL): Under-excited Vars must be limited to preventheating of the generator iron core and to ensure dynamic stability of the turbinegenerator. This is done by an under-excitation limiter that takes over when aspecified limit curve is reached and prevents operation below this limit.

V/Hz: The ratio of generator voltage to frequency (V/Hz) must be limited. Thisprevents overfluxing the generator and/or line-connected transformers caused byovervoltage operation or under-frequency operation, or a combination of the two.

Power System Stabilizer (PSS): The introduction of high gain, high initial responseexciters can cause dynamic stability problems in power systems. The advantage ofthese exciters is to provide improved transient stability, but this is achieved at thecost of reduced dynamic stability and sustained low frequency oscillations.

The PSS is an optionalfunction.

The PSS is fed with a synthesized speed signal based on the integral of acceleratingpower. This indicates the rotor deviation from synchronous speed. This signal isconditioned and fed into the summing junction of the continuously acting acregulator so that under deviations in machine speed or load, excitation is regulated asa composite function of voltage and unit speed. The stabilizer therefore produces adamping torque on the generator rotor and consequently increases dynamic stability.

Over-excitation Limiter (OEL): It is necessary to limit generator excitation currentoff-line to prevent overfluxing the generator and connected transformers. Online, itmust be limited to prevent field thermal damage. The limiting action is performed bythe excitation current regulator. The current regulator takes control of bridge gatingif the regulator (automatic or manual) calls for exciter field excitation current inexcess of a predetermined pick-up level.

The dc or manual regulator is configured as a field current regulator using shuntfeedback and comparing it to the manual regulator static adjust reference. It willmaintain a constant exciter field current based on the setpoint adjuster. The onlineand offline field current regulators are low value gate selected with the inner loopregulator output to select the appropriate firing level for the IGBT bridge.

ScalingIt is necessary to scale the software in each exciter for application with a particulargenerator. The regulators use normalized values of counts to represent one per unit(1 pu). Typically 1 pu equals either 5000 or 20000 counts. This means that thefeedback value for a particular variable, such as dc link voltage (VDCLINK = 1 pu)or bridge current (AFFL = 1 pu), must be normalized by using a multiplier to equalthe prerequisite value of counts when it is at 1 pu. See Chapter 4 for more details.


FaultsRefer to GEI−100242 for faultcodes, interpretation, andtroubleshooting.

The EX2000 exciter has a sophisticated self-diagnostic capability. If a problemoccurs, a fault code flashes in the programmer display showing a fault name andnumber. The fault number also appears on the display on the LDCC in coded form.

SimulatorLocated within the core software is a sophisticated system simulation program thatmodels the exciter and generator behavior. The simulator is activated via a softwarejumper in EEPROM.

The simulator physically operates the field contactors when astart signal is issued to the exciter. If dc link voltage is present,current may flow in the exciter field.

This tool is useful fortraining, startup, andcalibration checkout.

Signals representing the field and the generator feedbacks are simulated in themicroprocessor application board (TCCB) and fed to the transducering algorithms,in place of the real feedbacks. Once the exciter is scaled for a particular generator,the simulator uses that scaling. For example, after a successful startup sequence isperformed in simulator mode, the operator interface will displays the exciter voltageand current and generator voltage applicable to that particular unit.

Note Scaling and operation of the simulator is discussed in Chapter 6.

Human-Machine Interface (HMI)Refer to the controlelementary supplied with theequipment for furtherinformation.

The PWM has a HMI datalink with the turbine controller over the Status_S page forregulator information. Optional interfaces include, discrete switches and meters,direct DCS control through an Innovation Series Controller, or some other device.

GEH-6375A User's Guide Chapter 2 Hardware System Description •••• 2-1

Chapter 2 Hardware System Description

IntroductionThis chapter describes the EX2000 PWM regulator hardware structure, and overalloperation. When reading these descriptions, refer to Figure 1-2, the specific unitelementary, and the excitation layout diagrams provided with the equipment.

Section Page

Packaging ........................................................................................................... 2-2Environmental.............................................................................................. 2-2Enclosure ..................................................................................................... 2-2

Ratings ............................................................................................................... 2-3Input Ratings................................................................................................ 2-3Output Current Rating .................................................................................. 2-4Voltage Control Range ................................................................................. 2-4Power Profile Rating .................................................................................... 2-4

Power Converter Hardware ................................................................................. 2-5Ac and Dc Input Devices .............................................................................. 2-6Dc Link and Dynamic Discharge .................................................................. 2-6IGBT And IAXS Devices ............................................................................. 2-6Output Contactor MDA................................................................................ 2-7Output Shunt SHA ....................................................................................... 2-7

Control Electronics Module................................................................................. 2-7TCCB (DS200TCCB) .................................................................................. 2-8PSCD (IS200PSCD)..................................................................................... 2-8GDDD (IS200GDDD).................................................................................. 2-8PTCT (DS200PTCT).................................................................................... 2-8NTB/3TB (531X305NTB)............................................................................ 2-9LTB (531X307LTB) .................................................................................... 2-9RTBA (DS200RTBA) .................................................................................. 2-9ACNA (DS200ACNA)................................................................................. 2-9

Inputs and Outputs .............................................................................................. 2-9Generator Inputs........................................................................................... 2-94-20 mA Inputs ...........................................................................................2-10Generator Line Breaker Status .....................................................................2-10Generator Lock-Out Trip.............................................................................2-10Additional I/O.............................................................................................2-11

2-2 •••• Chapter 2 Hardware System Description EX2000, PWM Digital Regulator GEH-6375A

PackagingGEI-100228 provides information on Receiving, Storing, and Warranty Instructionsfor DIRECTO-MATIC 2000 Equipment. This document should be consulted uponreceipt of the regulator.

Each regulator will withstand the following environmental conditions withoutdamage or degradation of performance.

EnvironmentalTemperature requirements for the regulator should be maintained within the limits inGEI−100228 during transport and handling. Once installed, the operational limits ofan ambient temperature of 0 to +45 °C, outside of the convection cooled cabinet,should be maintained. It is expected that the hottest board entry temperature will beapproximately 60 °C allowing the use of 70 °C parts. Maintain 5 to 95% relativehumidity with no external temperature or humidity excursions that would producecondensation.

The control equipment is also designed to withstand 10 ppb of the followingcontaminants:

• reactive sulfur

• reactive chlorine

• hydrogen sulfide

• sulfur dioxide

• chlorine dioxide

• sulfuric acid

• hydrochloric acid

• hydrogen chloride

• ammonia

EnclosureThe standard offering is a NEMA 1 or IP20 equivalent, 90 inches high by 24 incheswide and 20 inches deep. An optional 36 inch wide enclosure is also available. Insome instances, just the regulator panel without enclosure will be provided. Thispanel measures approximately 63 inches high by 17 inches wide by 18.5 inches deep.Other enclosure types are available.

The estimated weight is 1200 pounds with NEMA 1 24 inch enclosure, and 900pounds without enclosure. The estimated watt losses are a maximum 200 watts forall applications.


RatingsEach regulator has a specific output limit rating based on the application of theregulator and limited by the shunt chosen for the application. The following ratingsinformation is the maximum output of the standard regulator, using a 25 A shunt. Forshunt ratings other than 25 A, the output current limitations will be reducedproportionately. Name plate information should be used for accurate ratings.

Input RatingsThe ac input is the primary input power to the brushless regulator. The range of inputac is from 90 V rms up to 275 V rms. The ac input may be single or 3-phase. Theinput ac may be from a permanent magnet generator (PMG), customer suppliedauxiliary bus, or bus fed from the generator. The ac source input to the regulatorshould have an impedance of 6 % nominal based on an estimated 20 A, 10 kVAsource.

PMG InputThe voltage and frequency for PMG-based input will start from 0 and increase torated as a function of generator speed. Rated input from the PMG system can be ashigh as 250 V ac rms / 360 Hz. Nominal voltages can be 100 V ac rms up to 250 Vac rms. With overspeed conditions, the maximum is 275 V ac rms / 440 Hz. Sincethe PMG is ungrounded and only used to source power to the brushless regulator, noinput transformer is required. PMG systems on gas turbines will see extendedperiods of time at < 50 % speed operation on startup. This is due to the purge cycleneeded by the gas turbine. Since the PMG may be the only input power to theregulator, the control will initialize at ≤ 60 V ac rms (~50% speed).

Auxiliary Bus InputAuxiliary bus-based systems require an input transformer to isolate the input to thebrushless regulator from the customer power system. This insures that the powersource to the brushless regulator is ungrounded. The transformer can be external tothe enclosure that houses the brushless regulator, but will generally be located in thepanel. The secondary voltage can range from 90 V ac rms up to a max. 275 V ac rms.Nominal secondary voltages can be 100 V ac rms up to 250 V ac rms. Ratedfrequency for the auxiliary bus-based systems can be 50 Hz or 60 ±10%.

Bus Feed from the GeneratorBus fed-based systems will require an input transformer to isolate the input to thebrushless regulator from the power system. This also insures that the power source tothe brushless regulator is ungrounded. The transformer will be external to theenclosure that houses the brushless regulator. The secondary voltage can range from90 V ac rms up to a max. 275 V ac rms. Nominal secondary voltages can be 100 Vac rms up to 250 V ac rms. Rated frequency for the bus feed based systems can be 50Hz or 60 ±10 %. If a bus fed system is applied on a black-start gas turbine, this inputmay start at 20 % of rated speed, therefore, the voltage and frequency will start at 20% of rated.


DC Input PowerThe dc source input power is generally provided from a battery bus. This source is aback up to the primary ac input power source. It can be used as the primary inputpower for starting black-start turbine generators.

The nominal battery bus voltages are based on a 110/125/ 220 / 250 V dc. Therefore,the operating range for the dc input is from 80 V dc up to a max of 290 V dc.

Output Current RatingThe bridge is capable of delivering the following absolute maximum output:

• 25 A dc continuously over the specified temperature range

• 40 A dc for 20 s once every 30 minutes after continuous operation at 25 A dcover the specified temperature range.

The PWM bridge is monitored for excessive temperature by a heatsink sensor. Bothalarm and trip signals are available.

Voltage Control RangeThe PWM bridge is capable of two-quadrant operation (positive and negative outputvoltage, positive current). This allows operation near zero voltage. The PWM bridgehas two active transistors and will operate in zero vector mode. This will allow theoutput voltage to be chopped in PWM fashion from +V dc to 0 for positive voltagecommands and -V dc to 0 for negative voltage commands. The chopping frequencyis approximately 1 kHz.

The IGBT bridge does not provide a low impedance path, which would providerectification when gating is disabled. This prevents runaway conditions known tooccur on brushless units having rotating diode failure. The four flyback diodestructure provides this inherently.

Power Profile RatingThe output power profile is a function of line impedance, line current rating,operating point (I dc and V dc), and capacitor current rating. Peak current is limitedby IGBT rating. In general higher current output is available at lower outputvoltages. Output current (I dc) can be higher than line current rating. The regulatorshall be capable of matching the following power profile.

The continuous operating area is bounded by the minimum of the capacitor limit,line limit, 25 A dc, or maximum output curve and the x (V dc) and y (I dc) axis.

The y-axis shows input line amps (rms), capacitor amps (rms), or output amps (dc)for a given output V dc and I dc. The curve labeled 25 shows rms capacitor currenton the y-axis for a given V dc and 25 I dc.


0 50 100 150 200 250 300 3500

5

10

15

20

25

30

35

25

25 Adc

Output voltage (Volts dc)

Line and capacitor currents as functions of dc voltage and current

line limit 12.5 Arms

cap limit 10 ArmsLi

ne (A

rms)

, cap

acito

r (A

rms)

, or o

utpu

t (A

dc) c

urre

nt

IGBT limit25Adc

at 50 Vdc and 25 Adccapacitor current is10 Arms

at 200 Vdc and25 Adc

line currentis 15 Arms

maximumoutput

Figure 2-1. Typical Power Profile

The curve labeled 25 A dc shows rms line current on the y-axis for a given output Vdc and 25 I dc.

Negative voltage operation isnot shown.

The line limit curve corresponds to given V dc and I dc, which would result in ratedline current. The cap limit curve corresponds to given V dc and I dc, which wouldresult in rated capacitor current. The following graph illustrates the various limits.

Power Converter HardwareFor the following discussions, use elementary drawing 03A and the panel layoutdrawings (Figures 2-2 through 2-5) as references. The elementary drawing is typicalfor all applications. On a requisition basis, the output shunt (SHA), charge resistor(RCH), and dynamic discharge resistor (RDS) may change. Also, variouscombinations of the input source power may exist. A single phase PMG with batterybackup is assumed.


Ac and Dc Input DevicesThe ac input device DSWAC is a 3-phase, 600 V ac, 30A molded case industrialcircuit breaker. For single-phase applications, the L1 and L3 connections should beused. The dc input device DSWDC is a two phase, 250 V dc, 30 A molded caseindustrial circuit breaker. These input devices are mounted at the top of the panel,easily accessible for operation as a disconnect during equipment maintenance orinspection.

All of these components arelocated at the top of thepanel, behind the ac and dcdisconnects.

The ac input source is filtered by snubber RC networks and rectified by a 3-phasediode bridge (DM1, 2 and 3). The dc output of this bridge charges capacitors C1, C2,C3, and C4, forming the dc link. The dc supply is filtered through inductors (LPDCand LNDC) and battery capacitor C1F. It is then fed directly to the dc link throughisolation diode DM4. MOV1 and MOV2 are provided for surge protection.

Dc Link and Dynamic DischargeA charge control resistor (RCH) mounted on the heat sink assembly is provided tolimits inrush current during powerup and capacitor charging. The second pole of theMDA contactor controls application or removal of the charge control resistor. The dclink provides the source power for internal board power supplies via cable DCPL tothe PSCD board. The control power supply is designed to operate over a range of 60to 600 V dc on the dc link.

Auxiliary diodes DM5 allow stored energy in the exciter to be returned to the dc linkwhen the output contactor MDA opens. Excessive voltage buildup in the dc linkduring regeneration is controlled through the dynamic discharge circuit. This circuitmonitors the level of the dc link and will dissipate energy through the dynamicdischarge resistor (RDD) mounted at the top of the panel to prevent overvoltage ofthe power circuit and board rack supply. The C leg of the 3-phase IGBT pack iscontrolled by the dynamic discharge circuitry on the GDDD board. An alternatesource of power for the discharge circuit is provided through the RDS resistor, alsoto the GDDD board, in the event that control power is lost. Jumper settings on theGDDD board set the control level of the dc link by the dynamic discharge circuit.

IGBT And IAXS DevicesThe dc link also provides the unregulated power source for the Insulated Gate Bi-polar Transistor (IGBT) bridge used to provide the exciter field current. The bridgeconsists of legs A and B of the 3-phase, 50 A, 1200 V IGBT pack. Only leg A upperand leg B lower IGBT�s are active. Leg A lower and leg B upper are permanentlyinactive. Controlled by the microprocessor-based digital regulator, the leg A and Bare modulated to pulse the dc link supply and feed the resulting output to the field ofthe rotating brushless exciter. The output voltage is determined by the followingformula:

Voutput = Vinput * (time on/(time on + time off))

where Vinput is the dc link voltage, time on is the conduction time of the IGBTdevices and time off is the non-conduction time of the IGBTs. The choppingfrequency of the IGBTs is approximately 1000 Hz.


The IAXS board provides the connection of the dc link capacitors to the IGBTbridge, dynamic discharge control and gate control from the GDDD board. TheIAXS board is also the connection point for the dc output voltage and sensingfeedbacks to the control circuitry.

Output Contactor MDAThe output contactor MDA is described in GEK−83756. It is a double pole, singlethrow, 600 V dc, 50 A contactor, isolating the positive leg of the bridge output. Thesecond pole is used to remove the charge control resistor RCH. The power for thecontactor coil is provided from the PSCD board. This voltage is only present whenthe control has been commanded to run. When the dc link voltage is not present,there is no power available to drive this contactor.

Output Shunt SHAThe output current is monitored by the control via the 100 MV feedback shunt SHA.The shunt rating is application specific. A range from 1 A to 25 A maximum ispossible. The shunt rating must be less than twice the exciter amps full load.

Control Electronics ModuleThe control electronics module contains powerful programmable microprocessorswith companion circuitry, including EEPROM, to process the application software. Itis a module assembly that is located on the front door assembly of the powerconversion module. Elementary diagram sheet A04 and Figure 2-7 shows theconnections of the various boards in the control module.

This control module assembly contains the main processor board (LDCC),microprocessor application board (TCCB), power supply and contactor driver board(PSCD), and the gate driver board (GDDD). These boards are interconnectedthrough ribbon cables. Each board has a unique GEI, which documents the hardwarelayouts, test points, fuses and other information for each individual board. These arereferenced in Chapter 1.

The LAN and Drive Control board (LDCC), which is the main processor board,provides the IGBT gating circuit control and regulator functions including:

The LDCC board alsocontains both isolated andnon-isolated circuits forcommunication inputs to theexciter's controller. The LEDdisplay and keypadprogrammer is on this board.

• automatic voltage regulator

• field current regulator

• field current limit regulator

• volts/hertz limit regulator

• reactive current compensation

• under-excitation limit regulator

Optional functions include:

• VAR/power factor regulator

• power system stabilizer


TCCB (DS200TCCB)The microprocessor application board (TCCB) is essentially a transducer board. Theisolated and scaled generator PT and CT signals are fed from the PTCT board to theTCCB board. The TCCB uses voltage controlled oscillators (VCOs) to transform theanalog voltage signals into digital signals. Software transducers process the voltageand current signals and then calculate generator data. This information is passed tothe LDCC control processors for use by the regulators. The regulator simulationsoftware also resides in the TCCB.

PSCD (IS200PSCD)The Power Supply and Contactor Driver board (PSCD) is powered from the dc linkthrough stab-on terminals DCPL1 (+) and DCPL2 (-). The control operates from 80 -400 V dc as nominal range inputs. Transient operation to 600 V dc is possible duringmaximum operation of the dynamic discharge. This board produces control powerfor distribution to the other control module boards. The main supply produces ±24 V,±15 V, and +5 V for control boards (LDCC and TCCB) A 17.7 V ac squarewave isdistributed through high frequency transformers to the gate driver and LTB inputspower supplies. Auxiliary to the main supply are supplies for generating isolated 70V dc (sufficient to power 13 LUP inputs ) and an isolated SHVI/SHVM power forfuture applications.

The contactor control power supply from the PSCD board is sized to deliver up to0.75 A dc. Power is taken directly from the dc link and converted to 105 V dc by abuck converter. The enable of the MDA contactor is through an optically coupledsignal, which is logically in parallel with the coil of K1. Relay K1 is driven from theLDCC board when the control is commanded to run.

Relay K86 is used as the controls permissive to run and emergency stop. Droppingout K86 will immediately stop the regulator. Coil voltage is from the 70 V dc powersupply on the PSCD board.

GDDD (IS200GDDD)The Gate Driver and Dynamic Discharge board (GDDD) provides the interfaceisolation between the IGBTs and the main processor firing circuits. Dynamicdischarge circuit control is implemented on the GDDD board as well as the gatingcircuits for the A and B leg active IGBTs.

This board also provides the instrumentation of the regulator. Output dc voltage, dclink voltage, shunt current mV input, and the heat sink thermistor input are processedon the GDDD board and sent to the LDCC processors for use by the regulators.

PTCT (DS200PTCT)The Potential Transformer Current Transformer (PTCT) board isolates and scales thevoltage and current signals from the PTs and CTs. It also provides auxiliary inputsand outputs for either low voltage (± 10 V dc) or 4-20 mA current signals.Secondaries of the isolation transformers are passed to the TCCB board through theJKK ribbon connector.


NTB/3TB (531X305NTB)The NTB/3TB serves as a general purpose terminal connection board. Connectionsare made as an interface between the control core and other devices. The RS-232Cserial port is located on this board. When supplied, the field ground detection inputsfrom the ground detector receiver are connected to the auxiliary VCO inputs on theNTB/3TB board.

LTB (531X307LTB)The LAN Terminal Board (LTB) is an I/O termination board that serves as aninterface between the control core and other devices. Ribbon cable RPL allowssoftware variables pointed to the seven low voltage, low current, form C LTB outputrelays to control higher voltage, higher current, form C RTBA board relays. Jumpersettings on the RTBA board determine if the LTB relays or external connectionsoperate the RTBA relays. The eight LTB (or LUP) inputs are connected to the LDCCboard through 8PL for use by the regulator controls.

RTBA (DS200RTBA)The Relay Terminal Board (RTBA) board contains seven form C, DPDT relays thatcan be software driven via the LTB pilot relays or externally driven. The relaycontact outputs are used for external customer interface. Each relay contains an LEDthat indicates when the relay is energized.

ACNA (DS200ACNA)The Status_S data linkconnection to the turbinecontroller is made on theACNA board.

The ARCNET Board (ACNA) serves as the connection for the ARCNET data linkfor the regulator. Termination is made using co-axial cable. Each ACNA canterminate two co-axial cables.

Inputs and OutputsThe regulator has a limited amount of hard inputs and outputs (I/O) that can besupported. For most applications, these are to be conducted over the Status_S datalink. The following sections define the minimum I/O that must be supported.

Generator Inputs

Potential Transformer InputsUp to three sets of 3-phase PT inputs are supported. These inputs are a nominal 120V secondary with software adjustments available for other nominal secondaryvoltages. The inputs are less than a 10 VA burden on the PT inputs.

The first two PT sets are used to supply generator line voltage feedback informationto the automatic (ac) regulator for control of the generator output voltage. The firstPT set is used for generator control. The second set is used for PT failure detectionand can be configured for control should the first set fail.These inputs also supply speed/frequency feedback information for the regulators,limiters, and protection functions, including the optional Power System Stabilizer(PSS).


Optional PT isolationswitches for all three sets ofinputs may be supplied.

The third set of 3-phase PT inputs provides line side voltage and is used by thecontrol for an optional voltage matching feature. These connections are madedirectly to the PTCT board.

Current Transformer InputsOptional CT isolationshorting switches for eachphase input may be supplied.

One set of 2-phase CT inputs is supported. Phase A and phase C currents arerequired by the regulator. These CTs supply generator line current feedbackinformation for use by regulator, limiters, and metering functions in the brushlessregulator control, including the optional Power System Stabilizer (PSS). The inputsrequire a nominal 5 A secondary CT input. Software adjustments are available downto a nominal 3 A secondary input. The CT burden is less than 1 VA per phase. Theseconnections are made directly to the PTCT board.

4-20 mA InputsOptionally, the regulator can support two 4 to 20 mA inputs for signals used tomodify the overexcitation limiter/protection based on the cooling of the generator.On air cooled generators this input is proportional to the cooling air temperature forthe generator. On hydrogen cooled generators this input is based on hydrogenpressure of the generator.

Generator Line Breaker StatusOne form A contact input from the generator output circuit breaker is used bycontrol, limiter, and protection functions. This contact is connected to an LTB input.The contact may be powered using the 70 V dc supply from the PSCD board.

Generator Lock-Out TripOne form A (closed when reset) contact input from a customer trip relay (86Gtypically) is supported for an external trip of the excitation control system. Thiscontact must be powered from the 70 V dc power supply on the PSCD board.


Additional I/OIn addition to the I/O listed above, Table 2-1 lists minimum inputs and outputs thatare supported.Note Not all applications will require each of the contact I/O or 4-20 mA inputs oroutputs listed. Refer to the job specific elementary for those supplied.

Table 2-1 Minimum Inputs and Outputs supportedInput/Output Description

Input Regulator On / Off(Closed = Regulator On)

Used to start and stop the brushless regulator.

Input Regulator Selector AC/DC(Closed = AC )

Used to select the controlling regulator, auto (ac)or manual (dc).

Input Regulator Raise (Close =Raise)

Interfaces to the active regulator�s referenceadjuster, ac or dc, and raises the setpoint.

Input Regulator Lower (Close =Lower)

Interfaces to the active regulator�s referenceadjuster, ac or dc, and lowers the setpoint.

Input PSS Enable/Off (Closed =Enable)

Allows the PSS control to operate if minimumload permissives are reached.

Input Status of Control OutputContactor

Used to monitor the status of the MDA contactor.

Output Exciter Alarm (30EX) Provides a global exciter trouble alarm forcustomer annunciation.

Output Protective Transfer to dcRegulator / Transfer Regulatoralarm (60EX)

Provides an indication of an automatic transfer tomanual regulator.

Output Regulator On Provides an indication that the regulator isoperating

Output Exciter Trip Request(94EX)

Request from the regulator to immediately tripthe generator. Usually directed to the 86Gdevice.

Output Exciter Field GroundAlarm/Trip (64FA or 64FT)

Can be either an alarm or trip contact dependingon customer preference.

The voltage inputs supported are:

• Input from Exciter Field Ground Detector Alarm (+ 24 V)

• Input from Exciter Field Ground Detector Malfunction (+24 V)

• Input from Exciter Field Ground Detector Diode Fault (+24 V)

Up to four 4 to 20 mA outputs are also supported. These outputs are providedthrough the digital to analog converters on the NTB/3TB board. They are softwareconfigurable. Typical uses are regulator output voltage, regulator output current, andregulator balance.


Figure 2-2. Mechanical Layout

Note This layout is not certified for construction.


Figure 2-3. Front View


Figure 2-4. Front View (Door Removed)


Figure 2-5. Bridge Components


Figure 2-6. Bridge Components (Isometric)


MAINPROCESSOR

BOARD

LDCC

MICROPROCESSORAPPLICATION

BOARD

TCCB

POWER SUPPLYAND

CONTACTOR DRIVERBOARD

PSCD

GATE DRIVER ANDDYNAMIC DISCHARGE

BOARD

GDDD

PTCTBOARD

ARCNET BOARD

ACNA

LTB RTBA NTB/3TB

POWER CONVERTERMODULE (IGBT)

WORKSTATION

CONTACTINPUTS

CONTACTOUTPUTS

CONTACTINPUTS/OUTPUTS

TO TURBINE CONTROLOPERATOR INTERFACE

METER DRIVEROUTPUTS QTY (4)

3 PHASEVOLTAGESENSING

INPUT

2 PHASECURRENTSENSING

INPUT

RS232PORT

DC OUTPUTTO

EXCITER FIELD

AC INPUT

DC INPUT

1PL

3PL, 2PL 2PL GDPL, PPL

DCPL, MDPLJKK

4 PL, 2PL

GPL, 8PL

IOPL, 8PL

ARCPL

CPL

RPL

Figure 2-7. Typical Connection Diagram


Notes

GEH-6375A User's Guide Chapter 3 Software System Overview •••• 3-1

Chapter 3 Software System Overview

IntroductionThe regulator uses microprocessor-based software that includes adjustableparameters. These parameters perform many functions once controlled throughadjustable hardware and software combinations.

The parameters are modified to customize the regulator to the specific hardware andapplication. They also enable field and maintenance personnel to fine tune theregulator for optimal performance.

Use the Control System Toolbox (toolbox) and LDCC board programmer to makesoftware adjustments.

Section Page

Configuration Tools ............................................................................................ 3-2Programmer Module ........................................................................................... 3-2

Software Design........................................................................................... 3-2Standard Functions.............................................................................................. 3-3

Automatic Voltage Regulator (AVR) Ramp.................................................. 3-3Automatic Voltage Regulator Setpoint.......................................................... 3-3Automatic Voltage Regulator ....................................................................... 3-3Field Regulator (FVR) Ramp........................................................................ 3-3Field Regulator............................................................................................. 3-3Under Excitation Limiter (UEL) ................................................................... 3-4Over Excitation Limiter (OEL) ..................................................................... 3-4Firing Block ................................................................................................. 3-4

3-2 •••• Chapter 3 Software System Overview EX2000, PWM Digital Regulator GEH-6375A

Configuration ToolsThe toolbox is used to configure, maintain, and fine tune the regulator. It includes anextensive database of definitions, accessed and manipulated using menu drivenselections. Additionally, the toolbox can graphically display the exciter's programlogic on the computer screen. By viewing the logic flow, you can better understandand manipulate the exciter's adjustable values.

The toolbox is used at the factory to initially configure and test the systems. At thecustomer site, it enables GE field engineers and other trained personnel totroubleshoot, fine-tune, and maintain the installed regulator. Optional tool basedmodules provide real display of control variables and communications data.

Refer to GEH−6404 for more information and PC requirements.

Programmer ModuleThe regulator includes a programmer module with a 16-character digital display andan alphanumeric keypad. It functions as an operator interface for softwareadjustments and diagnostic testing when the toolbox is not available.

Note Permanent changes made using the programmer module must also be made inthe toolbox to keep them up to date with the exciter's software configuration. Getcontact information from GEI−100242.

Refer to GEI−100242 for more information on the programmer module.

Software DesignThe exciter application consists of functional software modules (blocks) combined toperform to system requirements. Block definitions and configuration parameters arestored in read-only memory (ROM), while variables are stored in random-accessmemory (RAM). Microcontrollers execute the code.

The exciter application emulates traditional analog controls. The software uses anopen architecture system, which uses a library of existing software blocks. Theblocks individually perform specific functions, such as logical AND gates,proportional integral (PI) regulators, function generators, and signal level detectors.

These blocks are tied together in a pattern to implement complex control systems.For example, a control function such as the under-excitation limit (UEL) is includedas an ac regulator input by setting software jumpers in EEPROM. The relevantblockware is enabled by pointing the block inputs to RAM locations where the inputsreside (the UEL requires megawatts, kilovolts and megavars). The UEL output isthen pointed to an input of the ac regulator summing junction.

This technique is similar totracing an analog signal byusing a voltmeter.

The software blocks are sequentially implemented by the block interpreter in anorder and execution rate defined in the toolbox. The blockware can be interrogatedwhile running by using the toolbox. The dynamically changing I/O of each block canbe observed in operation.


Standard FunctionsThese inputs and outputs canbe monitored through thetoolbox.

Table 3-1 is a description of the inputs and outputs for the more significant blocksused in the exciter. Also, the significant adjustments of those functional blocks aredescribed as adjustable constants. These constants represent limits, gains, andsetpoints. They are functionally equivalent to potentiometers or other discreteadjustment devices used in previous excitation systems.

Automatic Voltage Regulator (AVR) RampThe AVR ramp block accepts an input from the operator through the Status-S pagefor auto regulator raise or lower. The reference then ramps at a predetermined rate,within an upper and lower limit (usually 0.9 to 1.1 pu terminal V). The output can bepreset to a value upon startup. Automatic tracking of the AVR track value isperformed when operating in manual regulator (refer to Figure 3-2).

Automatic Voltage Regulator SetpointThe AVR setpoint block sums the output from the reactive current compensation(RCC), AVR ramp, UEL output, and power system stabilizer (PSS) output. This sumis compared to the V/Hz reference in a minimum select block and then passedthrough a high limiter as the AVR output signal. By selecting a negative or positivegain, line-drop or droop compensation mode may be selected on the RCC. Anauto/manual command by the operator generates auto active or manual active statusindicators. A PT failure can also select manual (refer to Figure 3-3).

Automatic Voltage RegulatorThe AVR block combines the AVR setpoint with the negative generator terminalvolts to provide an error signal. This is passed through to the automatic regulatorproportional and integral gain sub-blocks, and then passes through the auto regulatorlimits to the manual voltage regulator (refer to Figure 3-4). The auto regulator ismodeled by the following transfer function:

AVR out = AVR error (Kp + KI)/S

Field Regulator (FVR) RampThe FVR ramp block accepts an input from the operator through the Status-S pagefor manual regulator raise or lower. The reference then ramps at a predetermined ratewithin an upper and lower limit (usually 0.7 pu VFNL to 1.2 pu VFFL). The outputcan be preset to a value upon startup. When in auto regulator mode, the FVR ramptracks the value of exciter field current (IFE) (refer to Figure 3-5).

Field RegulatorThe exciter field regulator is configured as a current regulator. The reference input tothe FVR is from either the manual regulator ramp block or the AVR. When fed fromthe AVR, the field regulator is used as an inner loop. A bridge firing enabled signalis also provided to keep the exciter turned off until bridge firing is enabled (refer toFigure 3-6).


Under Excitation Limiter (UEL)The UEL blocks accept watts and volts as inputs and calculates a VAR reference.Using a table lookup, which approximates the underexcited capability of thegenerator, the Var reference is then compared to the actual unit Vars to develop aVar error signal. The error signal is then passed through a proportional and integralregulator sub-block to keep the machine within its underexcited capability (refer toFigure 3-7).

Over Excitation Limiter (OEL)A cool down function is alsosupplied to simulate coolingof the field after anoverexcitation condition.

The alternate current regulator is initially enabled. If the signal level detect lookingat exciter field current or either of the inverse time protection blocks activate, thealternate field current regulator is disabled and the primary current regulatorsetpoints are active. The output of either the alternate or primary field currentregulator is fed to the firing block where a minimum select with the field regulatorfiring command is performed (refer to Figure 3-8).

Firing BlockThe firing block accepts the field current reference and the field voltage referenceand then selects the least of the two. This signal is passed on to the bridge only if theinstantaneous overcurrent or the stop commands are not activated. If either of theseare active, the firing signal is a preset retard limit (refer to Figure 3-9).


Table 3-1. Standard Software Functions

Function Inputs Adjustable Constants Outputs

AVR Ramp Auto Increase (RF1@IN)Auto Decrease (RF1@DC)Manual Active (RF1@VE)Go to Preset (RF1@3E)Track Enable(RF1@T2)Track Value(RF1@2E)

High limit (RF1THO)Low limit (FR1TLO)Ramp rate (RF1NRT)Preset value (RF1@T3)Track lag (RF1WLG)

Reference out

AVRSetpoint

Frequency (ASP@FQ)React. Cur.(ASP@IQ)REF Out (ASP@RO)UEL Out (ASP@UE)PSS Out (ASP@PV)Auto/Man (ASP@AC)Extra Input (ASP@EX)PT Fail (ASP@PT)Gen Volts (ASP@VM)PSS Armed (ASP@PC)Gen Watts (ASP@WT)PT Fail Reset (ASP@PR)

ASP Limit High (ASPHLM)V/Hz Gain (ASPVHZ)RCC Gain (ASPRCC)PSS High Watt (ASPHIW)PSS Low Watts (ASPLOW)

AVR RefAuto ActiveMan ActivePSS ActiveV/Hz ActiveUEL ActiveSetpoint In LimitLatched PT Fail

FCR FCR Setpoint FCR@SPFCR Enable FCR@ENFCR Alternate SetpointFCA@SPFCR Alternate EnableEFA@EN

FCR Prop Gain (RGKC0)FCR Integral Gain (IRWIC0)Alt FCR Prop Gain (IRGKA0)Alt FCR Integral Gain(IRWIA0)

FCR OutputILOP0

AVR Generator Volts (AVR@FB)FVR Output (AVR@TV)AVR Ref (AVR@SP)Manual Active (AVR@TC)Bridge Fire Enabled(AVR@ZC)

High Limit (AVRPLM)Low Limit (AVRNLM)Prop. Gain (AVRPGN)Integral Gain (AVRIGN)Tracking Gain (AVRTGN)

AVR OutAVR In LimitAVR Error

FVR Ramp Manual Increase (SS)Manual Decrease (SS)Auto Active (RF2@2E)Go To Preset (RF2@3E)

High limit (RF2TH0)Low limit (RF2THL)Ramp rate (RF2NRT)Preset value (RF2@T3)

Reference Out

FVR Field Current (IFE)AVR Out (EFR@TV)FVR Ref (EFR@SP)Auto Active (EFR@EN)Bridge Fire Enabled(MPWRENAB)

FVR Turn Off (FLDZVL)Tracking Gain (FLDTGO)Proportional Gain (FLDPGO)Integral Gain (FLDIGO)

FVR Out


Table 3-1. Standard Software Functions - ContinuedFunction Inputs Adjustable Constants Outputs

UEL Watts (RA1@I1)Gen. Volts(@INPUT)Vars (R2@FBO)

Vars Ref. 0 (FGENYO)Watts Ref. 1 (FGENX1)Vars Ref. 1 (FGENY1)Watts Ref. 2 (FGENX2)Vars Ref. 2 (FGENY2)Watts Ref. 3 (FGENX3)Vars Ref. 3 (FGENY3)Watts Ref. 4 (FGENX4)Vars Ref. 4 (FGENY4)Prop. Gain KP (R2KFBO)Integral Gain KI (R2WI_0)High Limit (R2LMPO)Low Limit (R2LMNO)

UEL Output

OEL Field Current(CURRENT)

High Limit (CRLMHI)Low Limit (I2tAFL)FCR Preset (PIT@RS)Inst. Overcur. Lim (PITPU)IIT Limit (PITLM)FCR Pos. Limit (FCRPLM)IIT Cooling Mult. (I2tCMT)

OEL Act(FLDMOD)IIT Acc(PITIACCM)

Firing Block FVR OutFCR OutIOC ActiveStart/Stop

Retard Limit Firing Code


SETPOINT

EXIREAC RCC

EXWATTS

UEL

EXXMAG

EXVMAG

DETECTPT FAIL

LOWER

RAISE

SETPOINTREGAUTO

EXVFREQV/HZ

++

+

LOWER

RAISE

REG.MAN

AUTO/MAN

MAN

AUTO

PI

LOGICSELECT

REGULATOR REGULATOR

IFEEXVMAG

-

+

PI

-

+PI

FIRINGBRIDGE

AUTO EXCITER FIELD

VAR/PF CONTROL, POWER SYSTEM STABILIZERAND PT FAIL DETECTION ARE OPTIONAL.ALL OTHER FUNCTIONS SHOWN ARE STANDARD.

IFEEXVARS

EXVMAG

VOLTAGE LIMIT

GATE

LOWVALUE

SPARE

-

PSS

EXWATTS

Pa

ZERO LEVEL

+

ARM PSS

VAR

CONTROL/PF

EXWATTS

EXVARS

RUNNING

1177S

AND

FCR@SP

FCA@SP

SLD152G

HIGH SP

LOW SP

OFFLINE

ONLINE

I*T LIM

Figure 3-1. Software Overview


Figure 3-2. Automatic Voltage Regulator (AVR) Ramp

]

]

]

]

]

]

]

]

]

]

]

]

]

]

]]

]

]

]

+

+

+++

+

-

Figure 3-3. Automatic Voltage Regulator (AVR) Setpoint


Figure 3-4. Automatic Voltage Regulator (AVR)

Figure 3-5. Field Voltage Reg (FVR) Ramp


Figure 3-6. Field Regulator (FVR)

Figure 3-7. Under-Excitation Limit (UEL)


Figure 3-8. Over Excitation Limit (OEL)


Figure 3-9. Firing Block

GEH-6375A User's Guide Chapter 4 Software Configuration and Scaling •••• 4-1

Chapter 4 Software Configuration andScaling

IntroductionThis chapter gives examples of the scaling for specific parameters in a genericbrushless regulator generator application.

Section Page

Configuration and Scaling Example..................................................................... 4-2Example Generator, Exciter, and Regulator................................................... 4-3

General Configuration......................................................................................... 4-4Feedback Scaling ................................................................................................ 4-6

Generator Feedback...................................................................................... 4-6Bridge Voltage Feedback.............................................................................. 4-7Bridge Current Feedback .............................................................................. 4-8Feedback Offsets.......................................................................................... 4-8Instantaneous Overcurrent Trip..................................................................... 4-9

Regulator Scaling................................................................................................ 4-9Automatic Voltage Regulating System.......................................................... 4-9Under Excitation Limiter (UEL) ..................................................................4-13Reactive Current Compensator (RCC) .........................................................4-16VAR/Power Factor Control .........................................................................4-17Field Regulator (FVR).................................................................................4-18Field Current Regulator (FCR) ....................................................................4-20

Optional Functions Scaling and Configuration ....................................................4-23Transducer Outputs .....................................................................................4-23Ground Detector and Diode Fault Monitor ...................................................4-24Field Thermal Model...................................................................................4-25

The software to configure various regulators, metering, and protective functionswithin the regulator operates on a count system representing actual feedback values.These feedbacks are generated by current transformers, voltage transformers, and dcshunts. The signals may pass through isolators and amplifiers. These analog signalsare transformed to digital signals by voltage controlled oscillators.

4-2 •••• Chapter 4 Software Configuration and Scaling EX2000, PWM Digital Regulator GEH-6375A

The regulator controls use standard normalized values to represent the variable beingmonitored or regulated. This enables the use of software that, to a large extent, is notapplication dependent. For example, the automatic voltage regulator (AVR) controlsthe generator terminal voltage based on a setpoint chosen by the operator. For anymachine, 1 per unit (or rated terminal voltage) is defined within the AVR to be20000 counts. If the operator chooses to set the terminal voltage at rated then thereference to the AVR is 20000 counts. The voltage feedback counts are compared tothis reference to generate an error signal and the appropriate control action takesplace to maintain the feedback counts at 20000.

The actual generator terminal voltage being regulated is not referenced at this controllevel. It is therefore necessary to ensure that the feedback counts seen by theregulators are adjusted to provide the standard number of counts when the generatoris operating at rated. This is referred to as scaling.

An EX2000 system can be constructed several ways to accommodate customersystem requirements. For example, the regulator can be fed from the permanentmagnet generator or from an auxiliary bus. It can be a brushless regulator or an SCTcontrol winding regulator. The controls are set to match the hardware used. This isknown as configuration.

Configuration and Scaling ExampleThe following section shows how scaling is performed using example generator data.The example system is configured as a brushless exciter regulator fed from a PMGwith a 125 V dc battery backup. There is also a single set of generator potentialtransformers (PT)s and no line PTs.

The scaling may not apply to all EX2000 applications. ContactGE Industrial Systems before changing any EE values.

Note Operating data from the generator field is not readily available to theregulator. The generator information listed is critical to the overall operation andperformance of the regulator and excitation system. Assumptions made in the AVRand exciter field regulators are based upon the available generator data.


Example Generator, Exciter, and RegulatorGenerator Data

KVA 100000

Frequency 60 Hz

Volts 13800

PF 0.85

Cold Gas Temperature 40 °C

Rated Stator Amps 4184

Amps Field No Load 313

Amps Field Air Gap 281

Amps Field Full Load 846

Amps Field Ceiling 1360

Field Open Circuit Time Constant (T'do) 5.615 sec

Field Open Circuit Subtransient (T��do) 0.022 sec

Field Winding Resistance 0.199 ohms at 25 °C

Volts Field Full Load 136

Station battery volts 125 V dc

PT Ratio 14400/120

Current Transformer (CT) Ratio 8000/5

Exciter DatakW 268

Volts 300

Rated Exciter Output Amps 893

Amps Field Air Gap (exciter) 1.712

Amps Field No Load (exciter) 3.52

Amps Field Synch Imp.(exciter) 6.236

Amps Field Full Load (exciter) 9.54

Amps Field Ceiling (exciter) 15.45

Exciter Time Constant (T'do) 0.35 sec

Field Winding Resistance (exciter) 4.871 ohms at 25 °C

Regulator DataDC shunt 10 A = 100 mV

Dynamic Discharge Resistor 17.0 ohms

Dynamic Discharge Resistor Rated Amps 6.0 A

Charge Control Resistor 2.0 ohms

Voltage Doubling No

DC Link Expected Volts from PMG 137

Maximum Expected DC Link Volts 360


General ConfigurationThroughout this example, the software nomenclature is defined as follows:

EE.XXXX (ABCDEF)

where XXXX represents the software address location and ABCDEF represents thesoftware address name.

There are many parameters that are set in the regulator that are not discussed in thismanual. Many of them are used to set up configurable parameters such as theStatus_S data link, communication, and so on. These are fixed parameters such asbaud rates, display, configuration, and keypad configuration for all applications andshould not be changed or need changing on any requisition.

Note If any parameters not discussed in this document are in question, contact theproduct service group of GE Industrial Systems or the local GE service organizationfor advice.

The following list are general configuration adjustable parameters (EEPROM) usedto direct signals and help make the configurable blockware function as a brushlessregulator.


Generator Model Jumper EE.3850 (GMJMPR)EE.3850.1 Used to simulate PT failure in simulator mode. Normally set to 0.

EE.3850.2 Selects slip source for Power System Stabilizer (PSS) The examplehas no PSS

EE.3850.3 Selects extra PT source for calculation of PT failure. Can only befrom PTCT board for regulator. Set to (0).

EE.3850.4 Generator model type. Can be static (0) or rotating (1). Brushlessregulator is rotating.

EE.3850.5 Selects 50 Hz (1) or 60 Hz (0) system for simulator and normaloperation. Example is 60 Hz.

EE.3850.6 Selects terminal (0) or separately fed (1) inputs for bridge. Theregulator is separately fed.

EE.3850.7 Selects whether the extra PT is used for calculations if a PT failureis detected. (1) is yes, (0) is no. No PT failure detection available inthe example.

EE.3850.8 Selects location of extra PT input. Line side (1) of 52G breaker orgenerator side (0). Example does not have extra PT input.

EE.3850.9 Select if PT failure detection is always (0) or only with 52G closed(1). No PT fail detection in example system. Set to zero.

EE.3850.10 Use maximum of PT feedbacks for calculations. (1) is yes, (0) is no.No for example.

EE.3850.11 Adjusts simulator for 60 Hz (0) or 50 Hz (1)

EE.3850.12 Sets LOE calculation for high gain (rev. G1B) PTCT board for LOEcalculations. All new regulators use high gain PTCT inputs. Set to(1)

EE.3850.13 Adjusts PTCT board inputs for Rev. A (0) or Rev. B (1) board.

Configuration Jumper EE.589 (ECNFIG)EE.589.0 Selects IFG feedback to be from SHPL on GDDD (1), IA2PL from

GDDD (2) or none (0). Set to 1.

EE.589.2 Selects IFE feedback to be from SHPL on GDDD (1), IA2PL fromGDDD (2) or none (0). Set to 1.

EE.589.4 Selects VFG to be from APL/BPL on GDDD board (1), IA1PL onGDDD board (2) or none (0). Set to 0.

EE.589.6 Selects VFE to be from APL/BPL on GDDD board (1), IA1PL onGDDD board (2) or none (0). Set to 1.

EE.589.8 Selects field regulator feedback to be either VFG (0), VFE (1), IFG(2) or IFE (3). For current regulator set to 3.

EE.589.10 Selects source for Var.105 to be either IFG (0) or IFE (1). Set to 1for the regulator.

Other general configuration parameters important to the operation of aregulator

EE.550 Identifies product type, for hardware select 84.

EE.556 Identifies hardware feedback board, select GDDD board 2.


Feedback ScalingAs a brushless regulator, there are a limited number of feedback signals from thegenerator available. These are potential transformers and current transformersmonitoring the stator output, a shunt feed back from the exciter field, and exciterfield voltage. Main generator field current and voltage are not commonly availablefor display or control on a brushless generator. The following sections describecommon feedback signals and scaling.

Generator FeedbackThe PT and CT signals to the regulator are isolated by the PTCT board. The voltagesignals generated by the PTCT are sent to the TCCB transducer board. Here voltagecontrolled oscillators (VCO) translate the analog signals into digital counts.

The PTCT board will accept one set of 3-phase CT inputs from the main generatorstator current transformers. These CTs must have a nominal 5 A secondary andphase A and C are required for correct operation of the regulators. Phase B CT inputis not required and not used by the controls. EE.3840 CT_ADJ is used to account foroff nominal CTs. The scaling for this EE setting is calculated as equal to20480/(actual 1 pu CT secondary amps)

For the example generator data:

EE.3840 = 20480/(4184*5/8000) = 7832

The PTCT board also accepts up to three sets of generator voltage transformerinputs. These inputs are 3-phase inputs with a nominal secondary voltage of 120 Vac. Two of the inputs are for generator voltage before the synchronizing breaker.These two PT inputs should both be on the same side of the generator step uptransformer. The third input can be used for a line side of the synchronizing breakervoltage input. The scaling for this EE setting is calculated as equal to 491520/(actual1 pu PT secondary volts)

For the example generator data:

EE.3841 = 491520/(13800*120/14400) = 4274

Potential Transformer Failure Detector (PFTD) OperationIn the example system only one set of PT inputs are specified. The second set ofgenerator side PT�s can be used for an optional Potential Transformer FailureDetection (PTFD) function. The generator PTFD operates by comparing the sum ofthe absolute counts for V12 and V23 signals (generator PT signals) with the sum ofthe absolute counts representing the extra PT input signals VX12 and VX23.

The 1 pu secondary voltages from these two sources depends on the transformerratios used. A scale factor PTFDSC EE.3835 is used to null the signal differencethat could exist. The resulting magnitude difference is filtered and the absolute valueis compared to the failure detection level set by EE.3837 PTFDVL. Under normalconditions the difference between the two sums should be approximately zero. Ifthis absolute difference is greater than the value set by PTFDVL EE.3837 then a PTFAIL FLT.488 is generated and VAR.1183 EXVPTL becomes true. This variable issent to the excitation autosetpoint block input ASP@PT and, if true, forces a latchedtransfer to the manual regulator.


The PTFD can be disabled offline by setting EE.3850.9 GMJMPR.9 equal to 1. ThePTFD detector can be tested using the simulator by setting GMJMPR.1 equal to 1 tosimulate loss of V12 PT signal.

Setting EE.3850.9 GMJMPR.7 equal to 1, the extra set of PTs can be used for allcalculations downstream from the PT failure detector software.

PTFD ScalingParameter PTFDSC EE.3835, PT failure scale adjust, is used to null any signaldifference existing between V and X PTs. If a second PT for failure detection weresupplied, then set EE.3835 = 4096 * (1 pu V PT secondary volts/1 pu X PTsecondary volts).

In most cases, the second set of PT inputs would be the same secondary as the firstand the default value of 4096 would be used

PTFD Detection LevelThe failure detection level is set using PTFDVL EE.3837. It is typically set toapproximately 50% of nominal (120 V) PT signal (loss of half the voltage of onephase).

For the example system, EE.3837 = 0.5 * 2048 * (115/120) = 981. In the formula,2048 represents a complete loss of a PT signal and 115 is the actual 1 pu PTsecondary volts.

A PT failure detection causes automatic transfer to the field (or manual) regulator.This regulator controls field current level and does not look at generator terminalvoltage. This is the only fault that initiates automatic transfer to the manual regulator.It is not possible to transfer back to the AVR until this latching fault is cleared. Theoperator interface should indicate when a PTFD has occurred. A reset signal must besent to reset the PTFD. A soft reset of the core is necessary to clear the fault displayfrom the LDCC board once the PT feedback problem is fixed.

P.T.U.V.If a second set of generator PTs is not provided then the PTFD scheme describedabove can not be used. In this case the PTFD function is disabled by setting EE.3837to 65,535 and protection is provided by pointing ASP@PT at VAR.1182 EXPTUV.In the event of loss of one phase or complete loss of generator voltage signal asmeasured by the TCCB board, and after a time delay specified in EE.3834 PTFDT1.EXPTUV will become true, forcing the control into manual regulator mode.

Bridge Voltage FeedbackThe bridge (regulator) dc output voltage feedback signal is fed via APL-5 and BPL-6from the IAXS board to the GDDD board. A voltage controlled oscillator on theGDDD board converts this analog signal to a frequency and digital counts. JP1 onthe GDDD board is set per the maximum expected dc link voltage. For units notemploying the voltage doubling feature of the regulator, this is normally 640 or 360volts. The example system does not use voltage doubling.

The dc link voltage feedback signal is fed to the GDDD board via the DCPL -1 and 2connections on the IAXS board. Again, JP2 on the GDDD board is set to themaximum expected DC link voltage.


EE.612 VDCMAX sets the 1 pu count level (20000) equal to 360 or 604 volts forscaling of both the DC link voltage and DC output voltage. JP3 on the GDDD boardsets the operation level of the dynamic discharge firing circuit. The selection of JP3is also based upon the maximum expected dc link voltage. JP1, 2 and 3 on theGDDD board should all be set to the same settings.

Bridge Current FeedbackThe regulator field current feedback signal is from shunt SHA and is fed to theGDDD board via connections SHPL-1 and -2. This input is scaled using EE.1505CFISF0. This trims the gain of the VCO to achieve 5000 counts at 1 pu bridgecurrent. The scaling for this EE setting is calculated as EE.1505 = 32768*(shuntrating)/(regulator amps field full load). For the sample system, the shunt rating = 10A for 100 mV. The exciter AFFL rating is 9.54 A.

Set EE.1505 = 32768 *(10)/(9.54) = 34348

Feedback OffsetsDue to the tolerance limits of the op-amps and VCOs that provide the feedbacks, it ispossible that positive or negative offsets may occur with zero signal feedback. Theactual offsets produced are dependent on the actual hardware and must therefore bezeroed at startup. The bridge output voltage, dc link voltage and shunt feedback areadjustable using the following feedback offsets:

EE.1508 VF1OF0 is used to zero the VFB1 bridge voltage feedback offset. With nobridge output, variable 1014 should be read using diagnostic test 31. This countvalue multiplied by the constant -1141 and divided by the scale factor value inEE.612 VDCMAX then becomes the value in EE.1508.

For example, with power on the bridge but the bridge not firing, monitor VAR.1014(assuming VFE is the selected feedback) for any zero offset. Assume the offsetfound was approximately 80 counts. Set EE.1508 = (80*-1141)/360 = -253. Enterthis value and continue to monitor VAR.1014 to verify that the offset is now zero.

EE.1510 CF1OF0 is used to zero the CFB1 bridge current feedback offset. With nobridge output, variable 1016 should be read using diagnostic test 31. This countvalue multiplied by the constant 21475 and divided by the scale factor value inEE.1505 CFS1F0 then becomes the value in EE.1510.

For example, with power on the bridge but the bridge not firing, monitor VAR.1016(assuming IFE is the selected feedback) for any zero offset. Assume the offset foundwas approximately -100 counts. Set EE.1510 = (-100*21475)/34348 = -62. Enterthis value and continue to monitor VAR.1014 to verify that the offset is now zero.

EE.1513 VDCOF0 is used to zero the dc link voltage feedback offset. Since dc linkvoltage is required for control power, this offset must be made with dc link voltagepresent. VAR.1018 should be read using diagnostic test 31. The dc link voltageshould be read on the IAXS board connection points PL and NL. This measuredvoltage will then be converted to counts. The converted measured counts minus thecount value in VAR.1018 then becomes the value in EE.1513.

For example, with power on the bridge but the bridge not firing, monitor VAR.1018.Assume it is 7825 counts. Then assume the measured value of the dc link is 137volts. Converting the measured voltage to counts gives 137/360 * 20000 equals7611. Set EE.1513 = (7611-7825) = -213 counts. Enter this value and continue tomonitor VAR.1018 to verify that the offset is now zero.


Instantaneous Overcurrent TripAn instantaneous overcurrent trip occurs if the bridge current, as monitored by SHPL(CFB1), exceeds the threshold set by EE.1518 IOCTRO where 5000 counts = 1 pu.Set EE.1518 = 25000 (5 pu).

Regulator ScalingThere are several regulators and limiters available in the regulator. The applicableone-line or system ordering documents will detail whether or not all or any of theseare supplied on a given requisition. Generally the AVR, FVR, and OEL regulatorsare supplied as standard. The UEL, RCC, and V/Hz limiters are also generallystandard features. PSS and VAR/PF controllers are typically supplied as options.

Automatic Voltage Regulating SystemThe primary purpose of the automatic voltage regulator (AVR) is to control thegenerator terminal voltage according to a chosen reference. The terminal voltage canthen be modified by various limiter and regulator functions.

AVR Operation.The regulator is designed to be started in AVR. The exciter can be started in AVRmode with the generator operating from 20 to 100 Hz. To prevent initial overshoot,the integrator is held at the preset value until 95% voltage is obtained. For a normalbandwidth AVR, this also means forcing the regulator to its maximum output until95% of terminal voltage is reached. If the speed of the generator is below rated whenthe regulator is started, the V/Hz limiter will hold down the terminal voltage andregulator output such that the volts per hertz ratio specified in the AVR controls ismaintained.

REF1 OperationThe selected (unmodified) reference originates in the INC/DEC reference blockREF1 (see Figure 3-2). The initial reference used in the regulator is a preset valuenormally set for 1 pu generator voltage. The REF1 output tracks this value when astart is given to the regulator. During this initial operation the RAISE and LOWERcontrols are ignored.

Once the startup operation is complete, the reference can be changed by selectingRAISE or LOWER from the operator station with the regulator in AUTO regulator.When offline, selecting RAISE or LOWER controls the generator terminal voltageover a range set in REF1 (and the autosetpoint block). This range is normally ±10%of rated terminal voltage. When online, selecting RAISE or LOWER increases ordecreases the generator terminal reactive voltage and/or the power output of thegenerator. The more stiff the connection to the power system (lower impedance tie)the less the generator terminal voltage is able to change.

An optional volt ampere reactive/power factor (VAR/PF) controller can also controlthe output of the REF1 block. While under control of the VAR/PF controller, theslew rate of REF1 is slowed to an alternate ramp rate, and the operatorRAISE/LOWER inputs are ignored.


When the exciter is operating in manual, the autosetpoint reference REF1 tracks avalue representing the sum of ASP@VM (normally generator voltage) and thereactive current compensation signal. While REF1 is tracking this value, theINC/DEC commands from the operator station are ignored in the REF1 block. Theoutput of REF1 in VAR.282 REF1OUT0 is passed to the autosetpoint block(EXASP).

REF1 Scaling and ConfigurationREF1 tracks target RF1@T3 EE.3402 without delay during startup. It is normallypointed to a value of 20000 counts for 1 pu generator voltage. For 1 pu generatorvoltage set EE.3402 = 19. During startup, a quick store register can be used to presetthe terminal voltage to a value other than rated. This register can contain a countvalue representing the desired preset voltage. RF1@T3 should then be pointed to thisaddress. For example, during startup, if the desired preset voltage is 12.5 kV on a13.8 kV machine, the reference preset counts required is 12.5/13.8 * 20000 = 18116counts.

Quickstore EE.95, currently an unused register, can be used to store this value. Then,point EE.3402 (RF1@T3) to EE.95 instead of the normal EE.19 location.

The range of the AVR is set using EE.3414 RF1TH0 (upper limit) and EE.3412RF1TL0 (lower limit). Set this to provide a range of ± 10% of rated generatorvoltage. Set EE.3414 = 18000 and EE.3412 = 22000.

To select the ramp rate of the AVR set EE.3400.6 = 0 for a normal INC/DEC scalecontrol setting of 1/10 bits/sec. The time to ramp across the AVR range is set by thenormal INC/DEC rate EE.3421 RF1NRT.

The range of the AVR = (22000-18000) = 4000. The desired time to cover this rangeis 60 seconds taking into account the setting of EE.3400.6. Set EE.3421 = (4000/60)*10 = 667.

Autosetpoint BlockThe selected reference from REF1 enters the autosetpoint block (EXASP) as themain auto reference setpoint. This reference can now be modified in the autosetpointblock by various standard and optional regulators and limiters. In addition to theREF1 input the ASP block receives feedback variables for reactive current, generatorterminal voltage, generator frequency, the output of the under excitation limiter, andgenerator real power if a power system stabilizer (PSS) is used (see Figure 3-3).

Automatic regulation is enabled through the operator station or the A/M selectorbutton on the LDCC board programmer keypad. When auto is active, VAR.953ASPAUTOA will be true. The ASP block also has an input from the PTFD (orPTUV). When a PT failure is detected, regulation is switched to the MVR.ASPAUTOA becomes false and remains latched in that state until the PT feedbackproblem is corrected, the core is soft reset, and the PTFD reset button on the operatorstation is pushed to permit selection of AUTO operation. Configuration jumperEE.589 selections can disabled the PTFD while off-line.

The ASP block contains a summing junction, minimum value gate, and a positiveoutput limiter. The summing junction adds the output of REF1, the UEL regulatoroutput, the PSS regulator output (if present), and an extra input ASP@EX. This extrainput can be used to insert a test signal. The RCC compensation signal is subtractedin the summing junction.


The output of the summing junction feeds a minimum value gate where it iscompared with a V/Hz limit signal proportional to the generator frequency by anamount set in EE.3789 ASPVHZ. The minimum of these two references is used asthe reference sent to the regulator. The maximum output is limited to a value set inEE.3790 ASPHLM. If the reference used by the regulator is the V/Hz limit and theexciter is in auto, then VAR.958 ASPVHZA is set true and an indication is given thatthe exciter is in V/Hz limit.

If a positive value is input to the summing junction from the UEL and the exciter isin auto, then VAR.959 ASPUELA is set true and an indication is given that theexciter is in UEL. The output of the AVR setpoint block VAR.158 ASPAVRSP issent to the AVR block as the regulator reference signal.

Autosetpoint Block Scaling and ConfigurationFor the example system the V/Hz limiter will be set to 110%. Set EE.3789, the V/Hzgain, to 282 (256 = unity). For 50 Hz applications, multiply EE.3789 by 6/5.

The ASP High Limit is set in EE.3790 ASPHLM. This is generally set for 110% ofrated or 22000 counts. For 50 Hz applications, multiply EE.3790 by 6/5.

Automatic Voltage Regulator (AVR) BlockThe AVR is a proportional plus integral regulator that compares the generatorterminal voltage feedback (derived from the V12 and V23 generator PT signals) witha reference from the auto setpoint block to produce an error signal. This error signal,VAR.156 AVRERROR, is fed to the PI regulator. If the regulator is in automaticregulator, the output of the AVR, AVROP VAR.157 is then fed to the inner loopfield regulator. The AVR output is limited to approximately 2 pu field current so thatit does not overdrive the exciter. The output of the AVR is passed through the fieldregulator to cancel the impact of the additional time constant of the rotating exciter.By doing this, the calculations and settings of the various regulator limiters, (UEL,V/Hz, OEL) can be set using the same rules as a terminal fed or bus fed excitationsystem. Tuning of regulators in the field is thus minimized.

The AVR is preconditioned to a value corresponding to AFNL at startup. The initialvalue of AFNL used could be an estimated value. After the initial startup, when aprecise value of firing command counts for AFNL is known, the preconditioningvalue stored in EE.92 can be adjusted accordingly.

When the precondition input AVR@ZC is true, the AVR output follows thepreconditioning value AVR@ZV. If AVRJMP.0 = 1 the integrator continues tofollow AVR@ZC until AVRERROR is less than 5% (1000 counts on a 20000 base).If, in addition to AVRJMP.0 = 1, AVRJMP.1 also = 1 then the output of the AVR isforced to maximum as set in EE.3772 AVRPLM until the AVRERROR is less than1000 counts. If the exciter is in MANUAL (ASPMANUA true), the AVR tracks theoutput of the field regulator FLOPO VAR.1004.

The AVR integrator has anti-windup protection that zeros the error feeding theintegral gain if either:

a. The output is in positive limit or if the regulator is in FCR and the error signalfeeding the regulator is positive.

b. The AVR output is in negative limit or in full retard and the error signal feedingthe regulator is negative.


AVR Scaling and ConfigurationThe AVR response is not set for optimum speed, but for acceptable performancewithout risking instability due to local mode oscillations. This setting is consideredto be a normal bandwidth regulator. A high bandwidth regulator is used when a highgain fast response AVR is required. The example assumes a normal bandwidthregulator. If a high bandwidth regulator is chosen, then the high bandwidth settingsfor the UEL regulator should be used also.

AVRJMP EE.3759.0 is set to 1 for AVR output to follow AVR@ZC until regulatorerror is less than 1000 counts. Set at 1 for a high bandwidth exciter also.

EE.3759.1 is set to 1 on a normal bandwidth exciter to hold AVROP in ceiling untilAVRERROR is less than 1000 counts. Set to zero for a high bandwidth exciter.

AVRPLM EE.3772 is the positive limit for AVR output. Normally set to 10000,which is approximately 2 pu current for the exciter field.

AVRNLM EE.3773 is the negative limit for AVR output. Set to 0.

AVRTGN EE.3770 is the AVR tracking gain. This sets the time delay for the AVRto track the output of the field regulator while in manual regulator. Set EE.3770 = 5(where 100 = 1 rad/sec) for a 20 second tracking filter.

The following is an example of setting the AVR regulator for an regulator withnormal bandwidth.

Prior to startup, the AVR output is preset to the no load exciter field current level.This effectively wipes out overshoot problems when starting in the automaticregulator.

VR@ZV EE.3764 points to EE.92. In EE.92, the RUN2RF storage register stores thefiring command count value necessary to produce 80% exciter AFNL. In theexample, exciter AFNL was 3.52 A dc.Set RUN2RF EE.92 to a FIRCMD = 0.8 * AFNL* 5000/AFFL = 0.8*3.52*5000/9.54 =1476

AVR Proportional GainThe proportional gain of the PI regulator is set as follows:

1. Determine the transient gain requirements of the system.

2. Calculate the proportional gain, which is directly proportional to the transientgain. For the normal bandwidth regulator, set the transient gain to 4*T'do (theopen circuit field time constant) with 20 as a default minimum for new gas andsteam applications. A high bandwidth regulator should be set for a transient gainof 100.

From the transfer function of a brushless regulator, the relationship betweenproportional and transient gains is:

Transient gain = (Kp*20000 * Kex*AFFLex) / (VFAGgen*5000) where Kex is the gainof the exciter. The gain of the exciter is calculated as the (voltage out/current in) or((VFFLgen at 100 C - VFNLgen at 100 C) / (AFFLex - AFNLex)). For the examplesystem, Kex is calculated to be (216-80.13)/(9.54-3.52) = 22.51.


VFAGgen is the air gap voltage, which is determined by reading IFAG from themachine estimated air gap line at 1 pu armature voltage. The example generator hasIFAG of 281 A dc. The rated field resistance Rf@rated temp is defined as 100 C.The Rf@100C was not given and is therefore extrapolated from Rf@125C to giveRf@100C = .256 ohms. VFAG = .256 * 281 = 72 V dc.

Solving for Kp gives Kp = (transient gain * VFAGgen*5000) / (20000 * Kex*AFFLex) =(20*72*5000) / (20000*22.51*9.54) = 1.67.

Set AVRPGN EE.3769 = 1.67 * 256 (where 256 = unity) = 429

Integral GainSet Kp/Ki = 1 for a lead time constant of 1 sec. For the example Ki = Kp = 1.67

Set AVRIGN EE.3771 = 1.67 * 100 (where 100 = 1 rad/sec) = 167

Under Excitation Limiter (UEL)The two basic problems with operating a generator in the underexcited region of thecapability curve are stator end iron heating and generator steady state stability limit.Stray flux in the end turn region of a high speed steam or gas turbine drivengenerator can cause large losses in the core end iron during underexcited operation.

The steady state power stability limit indicates the maximum real power that can bedelivered at constant field voltage. The effect of the high initial response AVR is tosubstantially increase the steady state stability limit. The generator must beconstrained to operate in the underexcited region in an area where the unit would bestable if a transfer were made to the field regulator.

The thermal limit is usually more restrictive than the power stability limit. Thedefault scaling of the UEL curve described is based on the generator capabilitycurve. The intent is to protect the generator from end iron heating effects by settingthe UEL approximately 10% above the underexcited reactive capability curve. The10% is chosen to give sufficient safety margin.

The stability limit is a function of the network to which the generator is connected.The customer is responsible for system stability protection settings. If the customersupplies UEL curve points, enter those values instead of the values from the methoddescribed.

UEL OperationThis section describes the UEL operation, which is performed by a combination ofstandard blocks (see Figure 3-7). The capability of a generator when plotted on areactive power versus real power plot changes as terminal voltage changes. Thismeans that a number of curves are required to provide protection over the normal10% terminal voltage range permitted by the AVR. If the real and reactive powersignals are normalized by dividing by the square of the terminal voltage then thecapability of the generator becomes a single curve.

The generator watts signal is first normalized by dividing by the square of thefiltered voltage signal. The resulting normalized power is then filtered and absoluted.This value is fed to the function generator block where the normalized pu UEL curvehas been entered. The output of the function generator block is the UEL curve pointcorresponding to that value of generator real power output. This value then becomesthe UEL limit allowed.


This UEL limit as read from the curve is normalized Vars and must be multiplied bythe square of the filtered voltage signal to produce a Var reference for theproportional plus integral regulator. The PI regulator is enabled by an AND gate if52G is closed and the AVR is in control. It compares measured generator Varsfeedback quantity with a reference limit derived from the UEL curve to generate anerror signal that feeds the regulator.

The output of the PI regulator block is fed to a limiter set to allow only positiveoutputs. This value is then fed to the excitation autosetpoint block ASP@UE input. Itis added to the existing AVR setpoint to produce an increase in the excitation levelsufficient to prevent the excitation decreasing below the level corresponding to theUEL limit curve chosen.

UEL Scaling and ConfigurationConfiguring and scaling the UEL function involves setting the PI regulator forproper gain and time constants. It also includes setting the UEL curve based on thegenerator capability curve.

The UEL limiter uses process regulator #1. This is a proportional plus integralregulator. A PI regulator has the form:

Kp + Ki/s where Kp = proportional gain and Ki = integral gain (rads/sec).Only two sets of adjustments for the UEL regulator are necessary. One for excitersusing a normal bandwidth AVR and one for those customers requiring a higherbandwidth, such as a fast response/high gain AVR. The default setting is normalbandwidth. The recommended settings are as follows:

Normal High

EE.5899 = 200 (Ki = 2 rads/sec) EE.5899 = 200 (Ki = 2 rads/sec)

EE.5900 = 819 (Kp = 3.2) EE.5900 = 410 (Kp = 1.6)

Note Two EEPROM values are set because the command and feedback gains areindependently adjustable.

Steady state stability of the UEL can be verified by operating the generator at variouspower levels then slowly lowering the excitation to drive the generator into the limitcurve. Dynamic closed loop response can then be verified by stepping the AVRsetpoint using the excitation autosetpoint block extra input ASP@EX. A step of 1 or2% is sufficient. If it is not permissible to drive the generator into its true limit curvethen the curve could be reset at a safer level and the testing performed using thiscurve.

UEL CurveThe UEL limit curve is obtained by using a general purpose background functiongenerator block. This is a five point piecewise linear function generator. Thefunction is flat to the left of Y0, the first point, and to the right of Y4, the last point.The X coordinates must be monotonically increasing X0<X1<X2<X3<X4.


The coordinates are specified in counts, where generator 1 pu watts = 5000 countsand generator 1 pu Vars = 5000 counts. The underexcited portion of a typicalgenerator reactive capability curve is shown in Figure 4-1.

Generator Data: 100000 k VA

3600 RPM

0.85 PF

40 °C cold gas

13800 V

1 pu power at unity power factor = 100 MW = 5000 counts. This value was definedduring primary scaling of the generator voltage and current feedbacks. The excitercalculates watts and Vars from measured generator voltages and currents.

If the customer has not specified UEL settings, the following recommended settingscan be used:

Recommended X coordinates are at 0.3, 0.6, 0.9, and 1.2 pu MW. X = 0 is the Xcoordinate for Y0 point and needs to be entered. This gives the following values:

• X1 = 0.3 pu = 0.3*5000 counts = +1500 = EE.2864 (from the example curvethis is equivalent to 30.0 MW)




Next, the Y coordinates must be chosen. This method selects Y values 10% abovethe rated capability curve to provide ample safety margin. If more than one curve isgiven for different gas temperatures, use the rated curve. In the example given this is40 °C cold gas. From the chosen customer reactive capability curve, read the Vars at0 power. This is -35 MVars. Add 10% of rated kVA (not 10% of the reading) todefine the Y0 point. Y0 = -35 + (10% * 100) = -25 MVars. This value must now bechanged to counts to store in EE.2872.

EE.2872 = (-25/100)*5000 counts = -1250 counts = Y0

Y1, Y2 and Y3 are obtained as follows:

• Y1 = -40 MVars + 10 = -30 = -1500 counts = EE.2865

• Y2 = -35 MVars + 10 = -25 = -1250 counts = EE.2867

• Y3 = -17 MVars + 10 = -07 = -350 counts = EE.2869

The final value Y4 is chosen differently. A straight line is drawn from the Y3 pointthrough the 1 pu at unity power factor point to intersect the X = 1.2 pu power line.This gives Y4 = -2*Y3 = -2 * -350 = +700 counts = EE.2871. All this is based on theassumption that the 0.9 pu power point on the capability curve yields a negativevalue and the final segment passes through rated k VA at unity power factor. Thefinal point Y4 is chosen this way because this gives better coordination with loss ofexcitation protection.


Figure 4.1 UEL Curve

Reactive Current Compensator (RCC)The RCC signal is used to compensate for insufficient reactance between generatorsor when there is too much reactance. The RCC simulates a reactance on thegenerator output. If reactive current increases, the amount subtracted from theautosetpoint also increases. This lowers the excitation voltage and therefore theamount of Vars produced by the generator. It provides a drooping characteristic toinsure that the load reactive power is equally divided between paralleled machines.

Generally this compensation is required if machines are paralleled directly on thesame bus. If generators are paralleled on the high side of their generator step-uptransformer, then sufficient reactance should exist between the generators so thatadditional compensation is not required. The factory default setting is zerocompensation. Determine the amount of compensation necessary during initialstartup. The compensation is set to the minimum required to ensure VAR sharing.Values of 3% to 6% reactance are usually sufficient. (Alternatively, EE.3791ASPRCC can be set to a negative value to provide line drop compensation LDC).

RCC is set by EE.3791 ASPRCC, reactive current gain. The range of this setting is ±12.5% compensation. The setting for the +12.5% compensation is 32768 counts, or2621.44 counts per percent compensation. If an RCC of 4% reactance is desired, setEE.3791 = 4*2621.44 = 10486. If LDC is required, EE.3791 is set to a negativevalue. For a 4% line reactance, or line drop compensation, set EE.3791 = -10486.


VAR/Power Factor ControlA VAR/Power Factor controller can be provided as an optional regulator in theregulator core. Either VAR control where a constant generator VAR output ismaintained or power factor control where a constant generator power factor ismaintained can be selected. The two control actions are, of course, mutuallyexclusive. The PF/VAR controller can be configured to latch to the existing PF orgenerator VAR output when the associated control action is initiated.

The operator station is used to enable the PF/VAR controller. The operator mustadjust the generator to the VAR output or PF that it is desired to maintain. Theappropriate operator station button is then pushed to latch the output at the desiredvalue. To release the control action, the same button is pushed a second time.

VAR/PF Control Operation and ConfigurationThe PF/VAR control block uses the generator Vars and Watts as its feedbackvariables. These inputs are selected by EE.3718 PF@VAR, normally pointed toVAR.1153, generator Vars and EE.3719 PF@WAT, normally pointed to VAR.1152,generator watts.

The watt and Var signals pass through low pass filters, both of which are set byEE.3723 PFLPFW. A setting of 5 rad/sec is typically used (where 100=1 r/s).

The filtered Var signal is fed to a latch and the negative input of the controllersumming junction. The latch gets set when VAR control is selected. The inputvariable that controls VAR control selection is set by EE.3717 PF@ENV. When thisvariable is true, VAR control is selected. The latch holds the value of Vars that wasmeasured as the latch was set. This latched variable is fed to a switch. The switch isconfigured by EE.3720 PFARK. If PFARK is set to 0, then the switch will pass thelatched value of Vars to be regulated. If PFARK is set at a non zero value then thegenerator output Vars corresponding to this count value will be maintained. Thisfeature is typically not used.

The power factor controllerfunctions in a similar fashion.

The preset or latched Var setting is fed to a second switch that will pass either theVAR or PF reference to a summing junction depending on which control action hasbeen selected. If the Var setting was chosen, the VAR reference will be fed to thesumming junction where the actual VAR feedback will be subtracted to create anerror signal. This error signal passes through a deadband set by EE.3722 PFDEBD(5000 counts = 1 pu). The deadband setting should be chosen so that excessiveregulation does not occur while the required setting is accurately maintained. Fromthe dead band function a raise or lower signal is given to the exciter as required tomaintain the value selected. The raise signal is PFVRAISE VAR.718 and the loweris PFVLOWER VAR.719.

The same deadband settingapplies to either the PF orVAR controller.

The Var signal is multiplied by 32768 and then divided by the watt signal. Theresultant is the normalized tan of the angle between watts and Vars where 32768equals a tangent of unity (45 degrees). The resultant is filtered and then feeds a latchthat will be set if the PF control function is selected. The output of the latch feeds aswitch configured by EE.3721 PFVWTK. If PFVWTK is set to zero the latchedvalue is passed. If PFVWTK is set to a non-zero value, then the angle representedby the setting of EE.3721 will be regulated. A non-zero value is typically not used.The output of this switch is multiplied with the actual generator watts and divided by32768. The resultant is the generator Vars necessary to maintain the desired PF angleat the new generator real power level. This becomes the reference to the controllerssumming junction, where an error signal is developed which causes the exciter toraise or lower the generator Var output to hold the desired power factor.


Note The algorithm does not calculate the cosine of the angle between the generatorwatts and Vars so does not explicitly develop a signal representing the PF of thegenerator.

Field Regulator (FVR)The FVR (manual) regulates the exciter field without reference to the generatorterminal voltage. It is possible to configure the field regulator to regulate one of fourvariables. Either main generator field quantities IFG and VFG or exciter fieldquantities IFE and VFE are selectable. For the regulator, the field regulator isconfigured as a current regulator with IFE as the feedback variable. Normal regulatoroperation is in automatic voltage regulator with transfer to the manual regulator onlyoccurring as a result of losing the generator terminal voltage feedback signal(s) dueto PT failure detection. The PTFD detector is disabled off-line in certainconfigurations. In this case, the field current regulator (OEL) serves to limit theregulator output to prevent overfluxing the generator. The operator has the capabilityto switch the exciter to manual regulation by an operator station command (refer toFigure 3-5).

In automatic regulator, the field regulator receives an input from the auto voltageregulator and acts as an inner loop regulator in an attempt to cancel the effects of thetime constant of the rotating equipment. This allows for greater speed of responsewhen operating in automatic regulator. The AVR output is limited to 2 pu exciterfield current so as not to overdrive the regulator output.

REF2 OperationThe increase/decrease reference block normally supplies the field regulator referenceto the core block EXCOR. This reference block is identical in structure to the REF1block used by the AVR.

During exciter startup, the output of REF2 tracks, without delay, the value pointed toRF2@T3. This is EE.91 RUN1RF register. RUN1RF is set to the count valuerepresenting 80 percent of AFNLex. Normal increase/decrease control is disabled atthis time. If the exciter is in AUTO regulator and is not detected to be in limit thenthe output of REF2 tracks the variable pointed to by RF2@T2 which is normallyIFE.


The manual (backup) regulator tracks the field current necessary to maintain theexisting generator terminal voltage. This tracking is delayed to avoid followingtransient fluctuations or erroneous AVR behavior. The ramp range is typically set for70% of AFNLex to 120% AFFLex in 120 secs. The output of the REF2 block ispassed through a software switch to the core block and then to the MCP block as thefield regulator adjust command MFLDADJ VAR.165.

REF2 Scaling and ConfigurationThe present for the manual voltage regulator RUN1REF EE.91 is set to a count valuefor 80% of AFNLex . Set EE.91 = (0.8*AFNLex*5000/AFFLex) = 1476.

The REF2 ramp high limit is set to 120% of AFFLex. Set RF2THO EE.3444 =1.2*5000 = 6000.

The REF2 ramp low limit is set to 70% AFNLex. Set RF2LO EE.3442 =.07*(3.52/9.54)*5000 = 1291

Typically the ramp time to cover this range is set for 120 secs. Set RF2SLMEE.3446 = 0 for 1/10 bit/sec rate and RF2NRT EE.3451 = ((6000 - 1291)/120)*10 =392.

Tracking delay, set RF2WLG EE.3447 = 50

FVR OperationThe field regulator adjust command MFLDADJ VAR.165, which normallyoriginates as the REF2 output or a reference signal from the AVR, becomes thereference for the field regulator. This reference feeds a summing junction. Afeedback signal representing IFE is subtracted from this reference to give an errorsignal (FLOPERR VAR.1003) for the PI regulator. The output of the field regulator(FLOPO VAR.1004) goes to a minimum value gate where it is compared with thefield current regulator output (ILOPO VAR.1002). The minimum of the twobecomes the net firing command (FIRCMD VAR.1000).

FVR ScalingThe field regulator is set to cancel the effects of the time constant of the rotatingequipment by setting Kp/Ki = T�d0 of the exciter. With the loop gain set to unity, thetransfer functions of the inner loop reduce to be Ki = (2*pi*f*VFFLex @75C)/(Bridge Gain*5000). The bridge gain is the actual DC link voltage divided by11775, maximum firing command counts.

The field regulator bandwidth for the regulator is chosen to be 10 Hz.

In the example system, VFFLex is 9.54 * 5.810 = 55.4. The bridge gain is calculatedas 137 volts/11775 or .0116. Ki is calculated to be (2*pi*10*55.4)/(.0116*5000) =60. Set FLDIG0 EE.1551 = 60*65.536 = 3932 counts.

Since Kp/Ki was set to equal the time constant of the exciter, in the example system,Kp = Ki *0.35 or 21. From this, EE.1550 FLDPG0= 21 * 256 = 5376 counts.

FLDTGO EE.1547 sets the tracking filter for 2 secs. Set EE.1547 = 1/2 * 65.536=33 (where 65.536 = 1 rad/sec)


Transfer Tracking Meter and BalanceThere is automatic tracking between the manual and automatic regulators in eitherdirection with independent tracking delays. A balance meter is normally provided onthe operator station to show the amount of unbalance that exists between theregulators. While in the auto regulator, the unbalance is shown as the magnitude ofexciter field voltage unbalance that exists. If a transfer is made at this time to themanual regulator, the exciter field voltage jumps by this amount. While in themanual regulator, the balance is shown as the generator terminal voltage unbalancethat exists.

Field Current Regulator (FCR)The Field Current Regulator (FCR) is programmed within the MCP Block. Thisregulator is also a proportional plus integral (PI) regulator. The FCR has a featurethat allows for two sets of proportional and integral gains to be entered. The FCR canthen be switched between these two sets of gains through a command (EFA@EN) tothe Core Block. These two sets of gains are referred to as the primary field currentregulator and the alternate field current regulator. The primary current regulator isenabled when FCR@EN EE.3706 is true. The alternate current regulator is enabledwhen both EFA@EN EE.3705 and FCR@EN are true.

The regulator uses both of these current regulators as an Overexcitation Limiter(OEL) to limit exciter field current (and therefore main generator field current). Thealternate FCR gains and primary FCR gains are set exactly the same as the fieldregulator gains since the field regulator in the regulator is configured as a currentregulator. The alternate current regulator is always enabled unless an extendedforcing condition is detected, and is used as an instantaneous current limit. It has twosetpoints, one for on-line and one for off-line operation. The primary currentregulator is used as an inverse time limiter. Forcing is allowed for up to 10 seconds.If forcing is maintained for 10 seconds, the alternate current regulator is disabledwith control switching to the primary regulator. The primary regulator will then dropthe current to its on-line setpoint until the inverse time block activates and thencontrol is limited to 1 pu exciter field current.

In the off-line situation, instantaneous exciter field current is limited to 125% (orless) of AFNLex to prevent overfluxing the generator and connected transformers.On-line, the instantaneous current is limited to prevent heating (I2t) damage to themain field winding. However, it must allow proper field forcing for fault supportbefore beginning its current limit function.

When either the primary or alternate current limiter takes control of IGBT bridgegate firing, an OEL Active annunciation is displayed on or sent to the operatorinterface. The control of bridge firing is determined by a function referred to as aminimum value gate. The field regulator cannot resume control of bridge firing untilthe firing reference generated by AVR or FVR becomes lower than the firing signallimit out of the current regulator. See Figure 3-8.


Alternate FCROff-line, the alternate FCR limits the exciter field current to protect againstoverfluxing the machine and any connected transformers. It is a backup V/Hz limitwith the actual V/Hz limiter in the excitation autosetpoint block serving as a primarylimiter. Online, the alternate current regulator serves to limit the exciter field currentto a level that protects the rotating diodes in the brushless exciter.

The alternate field current regulator is enabled whenever EFA@EN true. Until thegenerator output breaker is closed, it will limit field current to the value in EE.82, theoff-line instantaneous setpoint. Once the 52G breaker closes, the alternate currentregulator limit is switched to the value in EE.80.

As stated before, since the field regulator (FVR) is configured as a current regulatorin the regulator, the proportional and integral gains for the alternate current regulatorare identical to those in the FVR.

Alternate Field Current Regulator ScalingEE.1541 IRGKA0 is the alternate FCR proportional gain. From the calculations forthe FVR in the example system, Kp for the current regulator is 21. EE.1541 will thenbe the same as EE.1550 = 256*Kp = 5376.

EE.1543 IRWIA0 is the alternate FCR integral gain. From the calculations for theFVR in the example system, Ki for the current regulator is 60. EE.1543 will then bethe same as EE.1551 = 65.536*Ki = 3932.

EE.1545 ILOPA0 is the alternate FCR preset value. In the regulator, this is chosen tobe 120% of the firing command for exciter field AFNL. For the example system, thiswould be (1.2*VFNLex@25 C*11775)/actual DC link voltage. EE.1545 =(1.2*3.52*4.871*11775)/137 = 1768 counts.

The off-line setpoint for the alternate current regulator is stored in EE.82. This valueis 125% of AFNLex which for the example system would be 1.25*(3.52/9.54)*5000= 2306 counts.

The online setpoint for instantaneous current limit must allow for forcing of theregulator during system transients. Generally, calculations are made that specify aceiling from the exciter to support 2 pu capability from the generator. The rotatingexciter diodes can be a limiting factor in what this on-line forcing capability is. Inthe regulator, this current level is conservatively chosen to be the maximum of either140% AFFLex or twice AFSIex unless a higher value is specified by the originalequipment manufacturer. In the example system, 1.4 * AFFLex = 13.356. Two timesAFSIex = 2 * 6.236 = 12.472. There is also a specified ceiling limit of 14.45 amps.EE..80 will then be 15.45 * 5000 /9.54 = 8097 counts. Before changing thisinstantaneous limit to a higher value, GE generator engineering should be consulted.

An off-line protection block, PRITC, is provided as an instantaneous trip if thepickup setpoint is exceeded when the regulator senses the unit is offline. It is set to avalue above the off-line alternate field current regulator setting. If this level isreached, the regulator will immediately stop IGBT gating.

The PRITC block is set up for linear error with pure integration (1 sec integrationtime). The pick up value is set to 1.25 AFNLex with the limit being activated as soonas the pickup level is exceeded.

Set PITJMP = 2. This sets the PRITC block for excessive I*t function .

Set PITPU = 125% of AFNLex For the example system 1.25*(3.52/9.54)*5000 =2306 counts the PRITC begins to accumulate when PITPU is exceeded.


PITTRP is set such that the unit will stop gating at a value of 160% of AFNLex. Forthe example system, this would be 645 counts. The trip setting is counts above thepick up level for a trip.

Primary FCRThe primary field current regulator is used to limit main generator field current to avalue so as not to exceed the thermal capability of the field copper. This limit mustbe imposed on the regulator output current into the exciter field in order to limit thecalculated main generator field current. The setpoints of the primary FCR aregenerally set to 125% of AFFLex until the inverse time protection is enabled and thenoutput current is limited to 1 pu AFFLex.

Forcing online is allowed until the reference level stored in a signal level detector(SLD1) is exceeded for 10 seconds or by a protection inverse time block being inlimit (PIT1LIM = true). The SLD level is set for 140% of AFFL. The protectioninverse time block, PRIT1, is set to begin timing at 1.06 pu exciter current and willactivate the second level of field current at 1.25 pu after 60 seconds. The fieldregulator setpoint must be lowered below the level of the field current regulators inorder to release control from the FCR or FCA.

Primary Current Regulator Scaling and ConfigurationEE.1540. IRGKC0 is the primary FCR proportional gain. From the calculations forthe FVR in the example system, Kp for the current regulator is 21. EE.1540 will thenbe the same as EE.1550 = 256*Kp = 5376.

EE.1542 IRWIC0 is the primary FCR integral gain. From the calculations for theFVR in the example system, Ki for the current regulator is 60. EE.1542 will then bethe same as EE.1551 = 65.536*Ki = 3932.

EE.1548 ILOPP0 is the primary FCR preset value. In the regulator, this is chosen tocall for full gating of the IGBT bridge. In the example system, this would be 11775counts.

The high level setpoint for the primary current regulator is stored in EE.83. Thisvalue is 125% of AFFLex which for the example system would be 1.25*5000 = 6250counts.

After the PRIT1 block times out, the current will then be reduced to the lower levelsetpoint for the primary current regulator which is stored in EE.81. This value is100% of AFFLex, which is equal to 5000 counts.

For SLD1, the level that the input (IFE) is to be compared with is set in EE.152SL1LEV. This value is set to 140% of AFFLex or 7000 counts. SLD1 pickup timedelay EE.154 = 1000 (for 10 second pickup)

The PRIT1 is an inverse time protection block. The scaling is set on a per unit basisof AFFL. As all machines are scaled to produce 5000 counts at AFFL then thevalues should not change on an individual job basis. The PRIT1 block is scaled forI*t function with a sixty second leaky integrator.

Set EE.3749.0 PITJMP = 0 This sets the PRIT block for excessive I*t function(protect for field heating).

Set EE.3749.1 = 0. This sets the PRIT block with a 60 second integrator.

Set EE.3751 PITPU = 5100 which is 102% of AFFLex. The protection block willbegin to integrate when PIT@IN exceeds 102% AFFL.


Set PITDEL EE.3755, integrator leak gain to 16122 counts. This setting allows thePRIT1 block to begin accumulating but never reaches a point where it will generate atrip. Essentially sets the accumulation level to 1.06% of AFFLex.

A trip level can be set in PITTRP EE.3752. If a trip is used, a setting of 783 willcause a trip signal output in 120 secs at 112% AFFLex and 42.3 secs at 125% ofAFFLex.

A transfer level can be set in PITTRF EE.3753. If a transfer is used, a setting of 666will cause a transfer action at 85% of the trip level.

PITDEL is set to 0 in EE.3755 so that pure integration is used. A constant errorsignal will produce a linear ramp of (PIT@IN -PITPU) counts/sec.

Optional Functions Scaling and ConfigurationSeveral optional functions are available with the regulator on brushless exciters.These include exciter field temperature calculation, field ground detection, and 4 - 20ma output transducers. The requisition specific elementary should be consulted todetermine which, if any, of these options have been supplied.

Transducer OutputsThe DAC1, DAC2, MET1, and MET2 analog outputs are available for test purposesand are typically used as the input reference for up to four isolated 4-20 ma outputtransducers. The four outputs operate identically and are programmed similarly tothe variables in Test 11. DAC1 and DAC2 have 12-bit resolution and are updated720 times per second. MET1 and MET2 have eight bit resolution and are updated360 times per second.

Each output has two addresses (see Table 4-1).

• The @I address selects the variable to be output (EE100 = DAC1, EE102 =DAC2, EE104 = MET1, and EE106 = MET2)The MX address is the maximuminput value (EE101 = DAC1, EE103 = DAC2, EE105 = MET1, and EE107 =MET2)

• DAC1 and DAC2 can be offset by the values stored in DAC1OF and DAC2OF

For example, to display this function:

1. In the Parameter Mode, call up EE100-DAC1 and EE101-DAC1MX (selectEE.100).

2. Enter the signal to be monitored into EE.100.

Putting that RAM address in EE.100 produces that signal at the NTB/3TB board'sDA1 testpoint and DAC1 terminal (3TB-53).

DAC2, MET1, and MET2 function like DAC1. When a signal's RAM address isloaded into the DAC and MET addresses, the signal is output on the NTB/3TBtestpoints and terminal points listed in Table 4-1.

Typically, the DAC and MET outputs are assigned with exciter volts (VFE), exciteramps (IFE), transfer volts, and occasionally exciter field temperature. Consult theelementary for the specific requisition to see which transducers are supplied, if any.Typically, DAC1 is exciter field temp, DAC2 is transfer balance, MET1 is IFE andMET2 is filtered VFE.


Table 4-1. Diagnostic Mode Analog Output Points

Loaded into Address NTB TP Terminal Board PointEE.100-DAC@1 &

EE101-DAC1MX

EE.108-DAC1OF

DA1 DA1, 3TB-53

EE102-DAC@2 &

EE103-DAC2MX

EE.109 DAC2OF

DA2 DA2,3TB-55

EE104-MET@1 &

EE105-MET1MX

MET1 MET1, 3TB-54

EE106-MET@2 &

EE107-MET2MX

MET2 MET2, 3TB-56

Ground Detector and Diode Fault MonitorThe regulator is capable of interfacing with a brushless regulator field grounddetector module. There are several different styles of ground detectors available,some with multiple inputs to the regulator, some with only one input. The mostcommon of these detectors is configured as follows.

This detector requires a 24 volt supply, typically passed through the regulatorcabinet. The detector returns three signals to the exciter. These are a GroundDetector Malfunction alarm, a Ground Fault alarm, and a Diode Fault alarm. Thesethree inputs are taken into the regulator controls on the NTB board at inputs V4VCO,FBVCO, and RFVCO. These inputs are configurable voltage controlled oscillators,which convert the analog input to dc counts for use in the regulator.

The Detector Malfunction alarm signal is a nominal 2 V dc when there is no faultpresent. This signal is scaled in the FBVCO and compared to a fixed reference in asignal level detect. A high signal (nominally 20 V dc) indicates a detectormalfunction.

The Ground Fault alarm is a nominal 10 to 24 V dc unless a ground fault is detected.Then the input will go to a nominal 2 V dc. This signal is scaled in the V4VCO,compared to a fixed reference and passed through a time delay such that thecondition must persist for up to 10 seconds. It is ANDED with the inverse of thedetector malfunction alarm. This prevents a false ground detection if the detector hasindicated that it is not healthy. To prevent inadvertent alarms when the unit is notoperating, the ground fault detector is not activated until the regulator has beenrunning for 15 secs. It is always disabled while in simulator mode to prevent falsealarms or inadvertant operation of the customer lockout.

The Diode Fault alarm sends a one hertz, 0 to 24 volt squarewave to the regulator.This signal is scaled in the RFVCO. It is then sent to two signal level detectors. Onechecks for a continuously low voltage, which indicates a diode fault. The otherchecks for a continuously high voltage, which indicates a diode, monitor fault.

Each of the inputs and resulting signal level detect outputs are incorporated in theglobal alarm string 30EX and also passed over the Status_S page.


Ground Detector and Diode Fault Scaling and ConfigurationThe Ground Detector Malfunction input is scaled in the FBVCO. The feed backVCO scale factor EE.1386 FVSCL0 is set to a value of 10000. This scales VAR.183to a nominal 20000 counts with an input of 20 V dc. EE.180 SL5LEV is the levelthat the input variable from the FBVCO is compared to. This is set to a value of18000. The mode of the level detect is set to a 0 in EE.178.11 SL5MODE. The leveldetect will then pick up when the input is greater than or equal to the sensing level.The level detect time delay is set to 0.5 seconds with a setting of 50 in EE.182SL5PUT.

The Ground Detection input is scaled in the V4VCO. The V4VCO scale factorEE.488 V4SCL0 is set to a value of 10609. This scales VAR.185 to a nominal 20000counts with an input of 24 V dc.

This variable is compared to EE.74 in the CMPR1 block. EE.74 is a general purposeregister and is set to a value of 2000 counts. If the output of V4VCO is greater than2000 counts, then there is no ground. The delay of 10 seconds is set in the ONDLY3block at EE.5670 ONDLY3. This is set to a value of 1000 for a 10 second delay.

The Diode Fault input is scaled in the RFVCO. The reference VCO scale factorEE.1281 RVSCL0 is set to a value of 10000. This scales VAR.182 to a nominal20000 counts with an input of 20 V dc.

For a diode monitor fault detection, EE.187 SL6LEV is the level that the inputvariable from the RFVCO is compared to. This is set to a value of 18000. The modeof the level detect is set to a 0 in EE.185.11 SL6MODE. The level detect will thenpick up when the input is greater than or equal to the sensing level. The level detecttime delay is set to 2 seconds with a setting of 200 in EE.189 SL6PUT.

For a diode fault detection, EE.194 SL7LEV is the level that the input variable fromthe REFVCO is compared to. This is set to a value of 2000. The mode of the leveldetect is set to a 4 in EE.192.11 SL7MODE. The level detect will then pick up whenthe input is less than the sensing level. The level detect time delay is set to 2 secondswith a setting of 200 in EE.196 SL7PUT.

Field Thermal ModelThe regulator monitors the temperature of the exciter field windings by calculatingthe field winding resistance from the measured values of exciter field voltage andexciter field current. In simulator mode, the model uses the simulated values ofexciter field voltage and current.

From the calculated field resistance, the temperature of the windings is calculatedusing the resistance formula for copper. This temperature is stored in VAR.1011,where it is displayed in degrees centigrade. It can be read directly or sent over theLAN to the operator station.

Thermal Model OperationThe voltage feedback, VFE (VAR.1014), passes through a limiter that restricts it topositive values. This prevents negative values of resistance from being calculated.The resulting voltage signal is fed through a filter that matches the field voltage tothe associated field current. This is accomplished by producing a lag thatapproximates the lag experienced by the field current due to the field time constant.The amount of lag is set using EE.1596 EFLTCO.

A switch is used to select either field voltage or a value of zero. Field voltage is theoutput if bridge firing is detected (VAR.882 MPWRENAB is true). This signalbecomes the numerator in a divide function.


The field current IFE (VAR.1016), after passing through a filter, feeds a limiter thatonly passes field current values greater than 500 counts. The signal then becomes thedenominator of the divide function. The result of the divide function is the fieldresistance in counts. Restricting the denominator to values above 500 countseliminates the possibility of division by zero.

The resulting resistance count value is normalized to Kelvin degrees by multiplyingby a scale factor set EE.1594 ERTSFO. The Kelvin degrees are then converted backto centigrade by subtracting 235. The temperature, now in degrees centigrade, isfiltered and passed though a limiter that restricts the output temperature range to 0 to300°. The temperature is output as VAR.1011 EFG, scaled at 1 count equals 1 °C.Due to the time constants, field temperature is not accurately modeled during startupand shutdown of the exciter.

Thermal Model ScalingThe example system uses VFE and IFE as the feedback variables. The modelparameters to be set are ERTSF0 and EFTLC0.

EE.1594 ERTSCO - Exciter thermal model resistance to degrees scale factor is set =(32 * Max V dc link * 5000 * (234.5+t1)) / (AFFLex*20000*(Rf@t1) From thesample data: DC link volts = 360 V dc; AFFLex = 9.54 A dc ; Rf@25C = 4.871ohms.

EE.1594 = 32*360*5000*(234.5+25)/(9.54*20000*4.871) = 16082 counts.

The exciter lag field time constant is set by EE.1596. From the sample data, the opencircuit exciter field time constant is 0.35 seconds. It will be set to (4096 * 0.458752)/(T�do exciter).

GEH-6375A User's Guide Chapter 5 Startup Checks •••• 5-1

Chapter 5 Startup Checks

IntroductionThis chapter contains basic checks to perform after installation and during initialstartup. Consult and study all furnished drawings and instructions before startinginstallation. These include outline drawings, connection diagrams, and elementarydiagrams. For installation details, refer to applicable sections of GEH-6011 andGEI−100228 Receiving, Storing, and Warranty Instructions.

These checks are not intended as complete commissioning instructions for theregulator, but serve as a guide for the sequence of tests and a description of functionsand devices requiring field tests.

Before application of any power source to this equipment, besure that no tools or other objects left over from unpacking orinstallation are present in the cabinets, including the bridgeassembly.

Section Page

Prestart Checks ................................................................................................... 5-2Energization and Simulator Control Checks .................................................. 5-2

Pre-start Power Checks........................................................................................ 5-4Initial Roll Offline Checks................................................................................... 5-6Online Checks..................................................................................................... 5-7Operator Interface ............................................................................................... 5-8

Units with Innovation Series Controller ........................................................ 5-8Units with Discrete Switches and Meters ...................................................... 5-8

5-2 •••• Chapter 5 Startup Checks EX2000, PWM Digital Regulator GEH-6375A

Prestart ChecksEach regulator is thoroughly tested before shipment. This testing process shouldensure that the regulator will perform properly upon receipt and loading ofrequisition specific software.

A complete inspection of the regulator and associated equipment should beperformed prior to energization of any portion of the regulator controls. Items tolook for are shipping damage to wiring or circuit boards, installation damage orforeign objects from the installation process, contamination due to improper storage,and loosening of connections and components.

Proper grounding and separation of wiring levels should also be maintained. Ensurethat the ground connection is sized properly and is connected to a suitable groundpoint.

Energization and Simulator Control ChecksThe following steps are intended as a guide for installation and initial startup of theregulators. Site specific procedures should incorporate these steps to ensurecompleteness.

1. Verify hardware, proms, and board revisions using the GE Control SystemToolbox (toolbox) and job specific software supplied with the equipment. Checkthe hardware including the shunt supplied, dynamic discharge resistor, chargecontrol resistor, and options supplied.

If changes to proms or circuit boards are required, a Full Calc in toolbox may beneeded. Contact GE Industrial Systems before changing any values generated bythe Full Calc if unsure of the correct settings.

2. Verify jumpers and switch settings as specified in the toolbox and the requisitionelementary. If changes are made, update the application tool databases to keepan accurate documentation of the regulator.

3. Perform a complete wire check of all external connections to the regulator.Inspections for unintentional shorts, induced voltages, correct wiring ampacities,and the like should be made. This will include PT and CT inputs, alarm contacts,trip contacts, and connections to the operator�s interface device. Ground detectorconnections and other optional equipment should also be checked.

4. With input disconnects open, check incoming ac and dc power for proper levelsand polarities. On units with a PMG input, it may not be practical to check thePMG inputs until initial roll of the equipment. At a minimum, a complete wirecheck of the inputs should be performed.


5. Energize the dc power supply feed to energize exciter regulator controls. Theregulator will go through an initialization process. During this initializationprocess, hardware and firmware diagnostic checks are performed. Any faultsgenerated during the initialization should be corrected before proceeding. IfInnovation Series Controller, Mark V, or Mark VI is supplied on the system,communication faults will not be cleared until this device is operational.

The LDCC display will default to its normal, de-energized state. It shouldappear similar to the following.

A S 97% I 0 %

The PSCD board has several LED indications of power supply levels and testpoints for checking the output of the regulator supplies. Check these testpointsfor appropriate voltage levels. Refer to the toolbox help messages or theindividual board GEI instructions for test points and voltages.

The dc link voltage should also be checked. Variable VAR.1091 should read thecorresponding voltage in engineering units and should agree with the levelmeasured. On the IAXS board, connections PL and NL are the positive andnegative link voltages respectively.

6. Turn off the dc supply and repeat the PSCD supply voltage checks for the acfeed to the regulator. The PSCD board voltages will be the same as for the dcfeed. The dc link voltage will generally be different than the dc link with onlythe dc supply voltage. Phase rotation of the ac input is not important in theregulator. But phasing should be checked to ensure accuracy in as builtdrawings. If a single phase ac input is used, it must be connected to L1 and L3leads of the ac input device.

Refer to the control elementariesfor proper connections.

If voltage doubling is required, the connections on CTBA-3 and CTBA-4 shouldbe made. Voltage doubling may only be used with a single-phase ac source.

After independent proper operation with both the ac and dc source voltages areobserved, both power sources should be energized at the same time. Eliminationof either source should have no noticeable affect on the regulator. Only the dclink voltage may be affected. This check should be performed during powerinitial checks.

7. Using toolbox, download the appropriate core file to the regulator. After thedownload is complete, the regulator will again perform a diagnostic check.

8. In order to thoroughly test the operation of the regulator, operation in thesimulator mode is recommended. Place the control core in the simulator mode(EE.570.0=1). See Chapter 6 for operation and scaling information of thesimulator. It is also recommended that as much testing as possible be performedin simulator mode. This should help shorten the pre-startup and initial rollchecks greatly since control functions, alarms, trips, etc. will have been testedand verified correct.

Note In the simulator mode, the regulator can generate a request for lockout. Thiscan trip the lockout relay unless the function is disabled.

9. It may be necessary to place temporary jumpers on inputs to simulate breakerclosures or start permissives that may not be operable at this time. Refer tohardware elementaries for specific jumpers required. If temporary jumpers areused, it is important to remember to check the operation of these inputs from theactual devices at some point during the pre-start process.


10. If the operator�s station device is available, start the device and test operation ofthe controls. Raise and lower signals, alarms, limits, displays and transduceroutputs are available in the simulator mode.

11. Close or jumper circuit breaker auxiliary contact (52G) input to simulate onlineoperation.

Change EE.84 value to simulate higher turbine load. UEL settings can bechecked by increasing EE.84 lowering the regulator output, and comparing tothe capability curve.

Note Return EE.84 value to (152*frequency/60) before opening the 52G contact orthe simulator will overspeed and cause a trip.

12. Verification of the operation of the online and offline OEL limiters can beaccomplished through the use of the built in simulator and toolbox. Aconvenient way to do this is to utilize the two input summation (2 Input Sum)block that is programmed between the REF2 block output and the CORE blockEFR@SP input. EFR@SP is the setpoint for the field regulator. The summationblock was added to the pattern for test purposes only. Input 1 of this block is thenormal field regulator reference supplied by REF2 output. Input 2 can bepointed to the output of the background test oscillator. In this manner theregulator can be easily stepped.

a. Offline OEL

While in manual regulator, raise the excitation level until the field currentexceeds the offline OEL pickup level. The system goes into off-line OEL.Lower the reference to see that the OEL condition resets. Step the reference intoOEL and observe the response. Return the summation block test input to zero.

b. Online OEL

While in manual regulator and with about 90% MW load, increase the Vars untilfield current is above 102% of AFFLex. The PRIT1 block begins to accumulateand after a time delay activates the OEL limiter. Lower the setpoint and thenstep the reference so that the system goes back into on-line OEL. Observe theresponse and be aware that if a very large step is used, the signal level detectorpickup level is also exceeded. After 10 seconds, the exciter field current will belimited to 125% of AFFLex and when PRIT1 times out it will limit to 100% ofAFFLex.

13. After completion of the tests, disconnect the test oscillator.

Pre-start Power ChecksAfter proper simulator operation, remove the control core from simulator mode. Asdescribed in the section Feedback Offsets, the inputs from the current and voltagefeedbacks should be adjusted. These offsets are found in location EE.1508 throughEE.1513. In simulator mode, these values are not in use and therefore do not affectthe simulator operation.

1. Check PT and CT inputs by applying an input signal with a 3-phase source atrated PT secondary volts and CT secondary current. The operator station deviceshould display rated terminal volts. Internal control variables for PT and CTfeedbacks should be verified for proper scaling. If supplied, a PT failure can bechecked by opening the primary switch and observing a transfer to the backupPTs or a transfer to the manual regulator.


2. It is recommended that the brushless exciter field be used for initial power tests.There should be no detrimental effects to using the exciter field as a load sincethe unit is not rotating and can not produce generator field voltage. If the exciterfield is not available, a suitable replacement load must be used. This dummyload has to be inductive. If a simple resistive load is used the control will trip oninstantaneous over current before the regulator can limit the current. Since theregulator is a current regulator, it should be sized to carry at least AFFLex inorder to keep as many EE settings at the requisition levels as possible. Choosinga smaller current load will require adjustment of several operating parameters.

3. Place the controls in manual regulator. Connect an oscilloscope and voltmeter tothe output load leads. Incorrect shunt wiring can cause the regulator to turn fullon in manual mode. Verify shunt connections with a mV source, observingproper polarities, before starting.

Again, test jumpers or operation of the 86G device will be required to run theregulator into the exciter field or replacement load.

4. Upon starting the regulator, exciter field current should develop toapproximately 80% AFNL. Immediately stop the controls if any unusual orabnormal operation occurs. Operation in the automatic regulator is notrecommended since the regulator will be open loop and be very difficult tocontrol.

5. Measure field voltage and current and compare to the operator station displayvalues. Use the toolbox to check the VCO output counts for proper values.While the scaling can be adjusted to give the desired counts for the indicatedvoltages or currents, it is generally an indication of improper scaling or jumpersettings when these values are not in agreement.

6. Check field output waveshapes using an oscilloscope. Observe for stableoperation at low and full output voltages. The display should be a square wavesimilar to Figure 5-1. As output is raised, the on time will increase as the offtime will decrease. The upper and lower peaks of the square wave will be equalto the dc link voltage.

DC LINK LEVEL

O VOLTS LEVEL

LOW OUTPUT HIGH OUTPUT

Figure 5-1. Typical Output Wave Forms


If found to be unstable,contact GE Industrial Systemsfor any changes in settings.

8. Use the method outlined in the OEL simulator testing in the sectionEnergization and Simulator Control Checks, step 12 to verify off-line and on-line OEL limit and regulator stability. A jumper for the 52G input will berequired to simulate on-line operation. It will not be necessary to simulate MWson the regulator. Raising the output current to the OEL settings should result inOEL limiter operation as described. For checks without the actual exciter field,it is possible to simulate higher current levels by changing the value in EE.1505.This value should be restored to the original setting after testing.

Refer to applicabledocuments and perform fieldground detector checks andsignal interface to theregulator.

9. Restore values and reconnect for normal operation. Check temporary inputs,jumpers and EE values and restore to the desired operational settings. To restorean EE value to its original, as shipped setting, use the clear override function inthe software tools. The unit is now ready for offline, initial roll system checks.

Initial Roll Offline Checks1. Run the unit up to synchronous speed. At this time the PMG input may be

available for the first time. Before applying the PMG input, measure andobserve correct PMG inputs. Refer to applicable PMG instruction manuals formore information.

2. With the regulator in manual control, start the exciter. The unit should come upto approximately 80% amps field no load. This should result in a build up ofgenerator terminal voltage no greater than rated terminal volts when operating atrated generator frequency.

3. Refer to applicable instruction manuals for initial startup checks for the rotatingportions of the brushless exciter and main generator. This should include grounddetector operational checks as well.

4. Check phasing of the PT inputs. CT inputs will not be available at this time.Measure for correct secondary values at rated generator terminal volts. Negativegenerator frequency counts indicate improper phase rotation of the PT inputs.

Check the values of exciter field volts and exciter field current at no. Measurethe actual field volts and field shunt mVs. The measured values, counts andoperator station display values should agree.

5. Step test the exciter field regulator to ensure stable operation. Step test the fieldvoltage regulator using the input summing block as described in the OELsimulator testing.

6. Transfer to automatic regulator. The transfer should be smooth and without anynoticeable fluctuations in generator or regulator operation. The AVR can bestepped by pointing the extra reference in the Excitation Autosetpoint Block(EE.3781 ASP@EX) to the output of the test oscillator. Generally a 2% step(400 counts) is sufficient. Verify stability of the AVR.

7. Give the regulator a stop command. With the unit in automatic regulator, restartthe exciter and watch for proper operation. The regulator should bring thegenerator to rated terminal volts (or the setting of the EE.3402 pointer).

8. The V/HZ regulator function can be checked by slowing the generator and,while in automatic regulator, watching the ac terminal volts drop accordingly. A1.10 pu ratio should not be exceeded.


The regulator is now ready for online operation. Return the unit to rated terminalvolts. Initial synchronization checks for other equipment may be required at thistime.

Online Checks1. It is recommended that the unit be synchronized in manual regulator the first

time. The CT inputs to the regulator can adversely affect the automatic regulatoroperation if they are not correct. Once the unit has been synchronized, increasethe unit load for a small amount of generator line current.Check the MW and MVAR displays for positive values. If they are negative, theCT leads connections may be reversed. This condition should be correctedbefore proceeding. If there are no CT disconnects, the unit must be offline toreverse/change CT connections.

Reversing CT leads with the unit under load can causesubstantial damage to generator components. The unit mustbe off-line, 52G open, before correcting CT lead polarity.

2. After correct displays of MW and MVars have been ascertained, place theregulator in automatic. For units without PT failure detection, remove the mainPT input by opening the disconnect switch (if supplied) or pulling the PTCTboard input connection plug. This generates a PT undervoltage alarm. Theoperator station display should indicate that the regulator has transferred tomanual, and can not be placed into automatic. A 30EX global alarm should begenerated. Restoring the PT input and operating the PT BAD reset will allow areturn to automatic. Activating the automatic regulator selection should againplace the exciter in automatic regulator. The 30EX alarm should be clear.Two PT inputs are required for PT failure detection. Opening the main PT willgenerate a PT failure alarm but the unit will not transfer to manual. It willcontinue regulation on the secondary set of PTs. Restoring the main PT inputwill clear the PT bad alarm.Removing only the secondary PT input will generate a PTX alarm but will nottransfer the unit from automatic to manual. Restoring the PT input will clear thealarm.Removing both the primary and backup PT inputs will generate the PTundervoltage alarm and the restoration process described above should befollowed.

3. Check UEL operation. The simulator checks should be sufficient to guaranteeproper operation of the UEL at the desired setpoints as long as the line currentand line voltage count values are correct. Many customers may requireverification of the actual UEL limit line. If this is needed, the UEL stabilityshould be checked first.Stability of the UEL can be checked by raising the UEL setpoints to a value ofjust slightly underexcited. The values of EE.2872, EE.2865, EE.2867, andEE.2869 should be set to negative 250 counts. Lower the excitation slowly untilthe UEL regulator takes over at the revised settings. The regulator can then bestepped into the UEL regulator using the extra input to the auto setpoint block asdescribed in the section Initial Roll Offline Checks, step 6. This will verify thatthe UEL operation is stable. Contact GE Industrial Systems if any instability inthe UEL regulator is encountered.


If at any time undesired operation is observed, a transfer to manual regulatorshould correct the condition. After verification of UEL stability, the originalUEL setpoints should be restored. If the customer desires testing of the actualUEL limits, the excitation can be slowly lowered into the limit.

4. The online OEL testing performed in the section Energization and SimulatorControl Checks, step 7 should be sufficient. To perform the same test on theactual machine requires operation at very high field current levels. GE Motors &Industrial Systems does not recommend that the equipment be actually driveninto OEL. If it is required, contact GE Industrial Systems.

After completion of all EX2000 tests, restore all storage registers used fortesting to normal values, back up the software, and disable all write enables.

As the unit is loaded, check for reactive sharing between paralleled units. Reactivecurrent compensation can be introduced through the AVR setpoint block bychanging the gain of the RCC. See EE.3791 help for changing the RCC gain.

Operator InterfaceThe regulator is a versatile regulator, capable of communicating with severaldifferent Human-Machine Interfaces (HMI). Direct communication with the GEturbine control is the standard interface to the regulator. The communicationconfiguration is defined and standardized within both the turbine controller and theregulator. Changes to the Status_S page and communication settings should be madeonly under advisement from GE Industrial Systems.

Checkout of the Status_S communications should be carried out in conjunction withthe turbine control startup procedures. Usually it is sufficient to verify control ofoperator functions as described on the interface control panel or screen.

Units with Innovation Series ControllerAll Innovation Series Controllers are factory-tested and operable when shipped to theinstallation site. Final checks should be made after installation and before starting theInnovation Series Controller/OC2000 combination. Consult the appropriateequipment GEH for guidelines for inspections to perform prior to startup.

GEH-6335 Operator Console 2000 Operation and Maintenance

GEH-6334 Unit Controller 2000 Operation and Maintenance

Units with Discrete Switches and MetersTesting of contact inputs and outputs from discrete meters and switches shouldinclude a thorough wiring check for continuity and no direct shorts before poweringthe devices from the regulator. Normal startup checkouts will ensure correctconnections and operation of the devices.

GEH-6375A User's Guide Chapter 6 Simulator Scaling and Operation •••• 6-1

Chapter 6 Simulator Scaling andOperation

IntroductionThis chapter gives example simulator scaling and operation instructions for a typicalbrushless regulator generator application.

Section Page

Simulator ............................................................................................................ 6-1Simulator Scaling......................................................................................... 6-2Operation ..................................................................................................... 6-4

SimulatorA simulator is built into the regulator that can model a generator and brushlessexcitation system off-line or on-line (connected to an infinite bus). Simulatoroperation is selected by setting EE.570.0 = 1. When selected, the feedbackspresented to the control regulators are switched, by software, from the real feedbackinputs to feedbacks derived by mathematical models mimicking the generator andfield circuit behavior.

The regulator controls react in a manner close to the way they would react in normaloperation. The simulator can serve as a valuable startup, maintenance, and trainingtool.

The simulator is scaled to represent the actual system as accurately as possible. Thismeans that when a start command is given to the exciter, it follows a normal startsequence. Close commands are sent to the bridge contactor but gating of the IGBTdevices is disabled. The controls look for actual auxiliary contact feedbacksrepresenting the contactor states. If these are not correct the appropriate faults aregenerated.

6-2 •••• Chapter 6 Simulator Scaling and Operation EX2000, PWM Digital Regulator GEH-6375A

The generator armature and field models, as well as the exciter stator and fieldmodels, provide the feedbacks for exciter field voltage and current and generatorstator voltage and current. These feedbacks are handled by the transduceringalgorithms the same way real feedbacks are used to calculate watts, VARs, speeddeviation, and frequency. If the model scaling is correct, the display data cannot bedistinguished from real data. Main generator field voltages and currents are alsosimulated internally and used for correct model operation.

The exciter regulator can be raised and lowered in automatic or manual regulator,both online or offline. The regulator limits come in at the same levels as in non-simulated operation. The regulator responses provide a good representation of whatcan be expected of the real system in response to step changes.By changing the storage register containing the value representing model shafttorque, EE.84, it is possible to raise or lower the generator real power output whensimulating on-line operation. The exciter changes the system VARs in response tochanges in the exciter setpoints.

Disable the IGBT gating while in simulator mode. Check thatsetting of EE.589.14 = 0.

Simulator ScalingThe goal of the simulator scaling is to make the models represent, as close aspossible, the behavior of the real system.

In addition to the following EE settings, see EE.3850 GMJMPR in Generator,exciter, and regulator parameters listed in Chapter 4 (General Configuration) in thesection Configuration and Scaling Example, will be used for scaling discussions inthe simulator section.

SMVDCL0 EE.1558 simulates the dc link voltage of the regulator. It is set torepresent the actual running voltage of the dc link. For the example system this is137 V dc. For EE.1558, set equal to 137/360 * 20000 = 7611 counts.

SMHST0 EE.1559 is the simulated heat sink temperature of the PWM IGBTheatsink. This value can be used to test the overtemperature alarm and trip levels inthe regulator controls. One count equals 1 °C. Normally set to maximum expectedtemperature during operation, 60 °C.

GMVBAT EE.3851 represents simulator flashing voltage. Since flashing is notrequired on the regulators, set EE.3851 = 0.

GMRBAT EE.3852 represents simulator battery resistance for field flashing. Thisis also not required in the regulator and EE.3852 is also set to a 0.

GMVTHY EE.3853 is the simulator thyrite voltage. This models an overvoltageprotection thyrite connected across the exciter field input. The example system has a125 V exciter field. Set EE.3853 = (Exciter field class*7.2*1797)/(DC link volts) =(125*7.2*1797)/137 = 11805.

GMRDIS EE.3854 simulates the dynamic discharge resistance. Set EE.3854 =(AFNLex*2*RDD*30664) / DC link volts = (3.52*2*17*30664)/137 = 26787.

GM_RFE EE.3855 is the simulator exciter field resistance. This is set equal to(VFNLex/DC link volts) * 31108 where VFNLex = AFNLex * Rfe@25C. From theexample data Rfe@25c = 4.871 ohms. VFNLex = 4.871 * 3.52 = 17.15 V dc. SetEE.3855 = (17.15/137)*31108 = 3838.


GMILFE EE.3856 represents the inverse of exciter field inductance. EE.3856 is setequal to (DC link volts * 156) / (VFNLex * T�doex). T'doex is the open circuit fieldtime constant which is 0.35 seconds in the example system. Set EE.3856 =(137*156) / (17.15 * 0.35) = 3561.

GM_RFG EE.3857 simulates generator field resistance. This parameter is normallyset to 7115 * frequency/60. The constant scaling is the result of expectednormalizations. Exciter AFNL is expected to produce VFNL on the generator field,which in turn produces AFNL on the generator field. Set EE.3857 = 7115 for theexample, which is a 60 Hz system.

GMILFG EE.3858 is the simulated inverse of generator field inductance. Set equalto (60/ frequency) * 670 / T'dogen, where T'do is the main generator field timeconstant. Set EE.3858 = 670/5.615 = 119 for the example system.

GMVFES EE.3859 is the simulator exciter voltage scale down divider. This scalesthe exciter voltage from the model to produce EXSIMFE VAR.1177 (simulatedexciter field voltage). Set EE.3859 = 5888 * maximum dc link volts / dc link volts =5888 * 360/137 = 15472.

GMIFES EE.3860 is the simulator exciter current scale down divider. Thisparameter scales the exciter current from the model to make EXSIMIFE VAR.1176(simulated exciter field current). Set EE.3860 = (AFFLex/AFNLex)*3146 =(3.52/9.54)*3146 = 8526.

GMVFGS EE.3861 is the simulator generator field voltage scale down divider.This parameter scales generator field voltage from the model to make EXSIMVFGVAR.1163. Set GMVFGS to 27329280/ (AFNLgen * RFG@100 C* 20000 /Maximum DC link volts). In the example system, and simplifying the formula, this is1367 * 360 / (313*0.256) = 6139.

GMIFGS EE.3862 is the simulator generator field current scale down divider. Thisparameter scales generator field current from the model to make EXSIMIFGVAR.1161 (simulated generator field current). When used in conjunction withstandard scaling, such as AFFL = 5000 counts, set GMIFGS = (AFFLgen /AFNLgen ) * 3146. In the example system, this would be 846/313*3146 = 8503.

GMIFLS EE.3863 represents the simulator flashing current scale down divider.This parameter is not used in the regulator. Set GMVIFLS = 0.

GMDAMP EE.3864 is the simulator generator model damping factor where 1 count= 0.11 pu watts/pu speed(60 Hz). Normally EE.3864 is set equal to 400. Ifoscillations occur while operating in simulator mode, try changing GMDAMP.

GM_IXS EE.3865 represents the generator model inverse of synchronous reactance.This parameter models the generator synchronous reactance in simulator mode.GM_IXS = 4096/Xs(pu).

To most accurately model the generator, it is necessary to approximate the generatorsynchronous reactance from no load to full load. In a real system, machinereactances vary with saturation and saliency. Therefore it is necessary to makesimplifying assumptions that produce a value of Xs that provides reasonablebehavior over the range VFNL to VFFL. Assume a round rotor machine with nosaturation, no saliency, and resistance is negligible. This makes the direct andquadrature reactances equal. If this level of accuracy in the model is not of concernthen Xd (the direct axis saturated synchronous reactance) can be used.

If optimum model accuracy is of concern then the following method, based on asimplified synchronous machine model, can be used. The range of field amps fromno load to full load = AFFL/AFNL=9.54/3.52 = 2.71.


If a phasor diagram showing the machine operating at rated load and power factorconnected to an infinite bus at rated terminal volts is drawn then a quadratic equationwith the synchronous impedance as the unknown quantity can be generated andsolved for Xs. It is then used in the above equation for GM_IXS.

The rated power factor for the sample machine is 0.85. With the machine operatingat rated k VA = 1 pu k VA then rated real power = 0.85*1 pu and rated reactivepower output = 0.53*1 pu Generator voltage = 1 pu

As per unit values are being used it is not necessary to use the actual generator MWand MVAR values involved.

From the phasor diagram, the following quadratic equation results where thegenerator internal voltage range required is represented by the ratio of AFFL toAFNL = 2.71

(2.71)**2 = (1 + 0.53*Xs)**2 + (0.85*Xs)**2 Solving for Xs gives a synchronousreactance of 2.04 pu

Set EE.3865 equal to 4096/Xs = 4096/2.04 = 2007.

GMXEXS EE.3866 models the effect of external reactance for the simulatorgenerator model. This can be set for a strongly or weakly connected system. EE.3866is set equal to 65536*Xe/(Xs + Xe) where Xe represents the amount of impedance inper unit connecting the generator to the system. For the example, set for a strongsystem (small amount of impedance between generator and system), with Xe = 0.1pu, then EE.3866 = 65536*(0.1)/(2.04 + 0.1) = 3062.

GM_IM EE.3867 models the effect of generator inertia for the simulator. Typically,the default value of zero (which is equivalent to M = 3.98 pu) is used. For moreaccurate simulator modeling, EE.3867 can be set to (frequency/60)*16302/M whereM =2H, the generator inertia constant.

OperationTo put the control core into simulator mode set EE.570.0 = 1. The shaft speed of thegenerator increases to rated (synchronous) speed at a rate determined by thesimulator inertia constant and the level of shaft torque preset in register EE.84. Thevalue of torque preset to give rated speed at no load is 153 * (frequency/60). Ratedspeed is indicated on the core programmer display as 100%. The shaft torque can bealtered on-line or off-line by changing the value stored in EE.84. Offline, changingshaft torque increases the speed and hence the frequency of the generator. Changingthe torque on-line increases or decreases the real power output of the modelgenerator.To start the simulator, it is generally necessary to wait until the simulated generatorspeed is above 95%. It is also necessary to have the 86G input to the regulatorclosed. Failure to do so will result in a fault 29 when attempting a start. Starts in autoor manual regulator are permissible. The simulator can be started from the operator'sstation or by pressing the RUN button on the LDCC keypad. After starting, exciterfield current and voltage and generator terminal voltage will build up to the presetlevels of the regulator being used.

Once the simulator is on-line, the 94EX contactoutput can be operated inadvertently. This maycause unintentional operation of protective devicesoutside the regulator. Lifting of the 94EX outputcontacts is recommended during simulatoroperation.


To put the simulator online, a contact closure simulating 52G aux contact feedbackmust be input to core LTB input IN1. Some oscillations are generally observed whenclosing the 52G contact since there is no synchroscope to confirm closing while thesimulated generator and line voltages are in phase. When offline, changing theexciter AVR or MVR setting adjusts generator terminal voltage. When online, raiseor lower signals change the generator VARs. The result of these control changes canbe observed.

Testing of UEL settings, V/Hz regulator, over current protections, and so on, canalso be observed. Feedback and control signals from the operator's station and 4-20ma outputs (if supplied) can also be observed.

When stopping the simulator, the reference value in EE.84 should be returned to theoriginal level for 100% speed off-line. Failure to do so will result in unusual offlineoperation.


Notes

GEH-6375A User's Guide Glossary of Terms •••• 1

Glossary of Terms

AFFLGenerator Amps Field full-load.

AFNLGenerator Amps Field No Load.

AFNLexExciter Amps Field No Load.

AFFLexExciter Amps Field Full Load.

ARCNETSee DLAN, DLAN+.

AVRAutomatic voltage regulator.

BoardPrinted wiring board.

BusAn electrical path for transmitting and receiving data.

CableA standard single conductor or combination of conductors insulated from each other.

CardAlternate term for printed wiring board.

ConfigureTo select specific options, either by setting the location of hardware jumpers orloading software parameters into memory.

GE Control System ToolboxA windows-based software package used to configure and perform diagnostics oncontrollers and drives.

2 •••• Glossary of Terms EX2000, PWM Digital Regulator GEH-6375A

ConverterA device that converts ac power to dc power, or vice-versa.

CTCurrent transformer.

DeviceA configurable component of a process control system.

DiagnosticsSoftware that checks drive hardware or software, providing error indications thatidentify the type or location of malfunction.

DLAN, DLAN+Communication links between exciters and controllers. There can be up to 32 dropson DLAN and 255 drops on DLAN+ (ARCNET).

Drive(Industrial). The equipment used for converting available power into mechanicalpower suitable for operation of a machine.

DCSDistributed control system.

DSWPower disconnect switch.

ECNFIGConfiguration jumper.

EEPROMErasable programmable read-only memory.

FCRField current regulator.

FVRField voltage regulator.

GDDDGate driver and dynamic discharge.

GMJMPRGenerator model jumper.

GroundAn electrical path designated to disperse high-voltage electrical spikes, usually byrouting them to the earth.

HMIHuman-machine interface.


IGBTInsulated-gate bi-polar transistor.

I/OInput/Output. Data flow into and out of a device, or the term for input/outputinterfaces.

LANLocal Area Network.

LDCCDrive control and LAN control board.

LTBLAN terminal board.

MDABridge dc output (field) contractors.

MOVMetal oxide varistor (a voltage suppressor).

NTB/3TBExciter Terminal Board, 53`X305NTB. The board containing the exciter's customerconnection terminals (3TB) for most signal-level I/O. It also contains most of thehardware customizing jumpers and potentiometers, plus passive interface circuitry.

OELOver-excitation limiter.

PFPower factor

PIProportional integral.

PMGPermanent magnet generator.

PPTPower potential transformer.

PSCDPower supply and contractor driver.

PSSPower system stabilizer.

PTCTPotential transformer current transformer.


PTFDPotential transformer failure detector.

PTF, PTPotential transformer failure.

PWGPulse width modulated.

RAMRandom access memory. Memory can be both read and written to.

RCCReactive current compensation.

RCHCharge control resistor.

RDDDynamic discharge resistor.

RDSDynamic discharge power source resistor.

ROMRead-only memory.

RS-232CAn EIA Recommended Standard (RS) for the serial link communications interfacefor interconnecting data terminal equipment, such as printers, computer monitors, orcomputers to data communications equipment, such as modems, for transmissionover a telephone line or network. RS-232C uses an unbalanced or single-endedvoltage interface.

RTBARelay Terminal Board, D5200RTBA. This board contains seven relays that can bejumper-selected to operate from LTB board signals or from external contacts. Eachrelay contains two form C contacts.

SHAOutput shunt.

ShuntA device having appreciable resistance or impedance connected in parallel acrossother devices or apparatus, and diverting some (but not all) of the current from it.Appreciable voltage exists across the shunted device or apparatus and an appreciablecurrent may exist in it.


TCCBMicroprocessor application board.

ToolboxSee control system toolbox.

UELUnder-excitation limit

VARsVolt amperes

VCOVoltage controlled oscillator. Its frequency output is proportional to the voltageapplied to it.

V/HzVoltage to frequency ratio.


Notes

GEH-6375 User's Manual Index •••• 1

Index

AAc and dc regulators

OEL, 1-7PSS, 1-7RCC, 1-7UEL, 1-7V/Hz, 1-7

ACNA board, 2-9Alternate FCR Scaling, 4-21Application software, 1-6Autosetpoint block, 4-11

Configuration, 4-11Scaling, 4-11

AVRConfiguration, 4-11Proportional gain, 4-12Scaling, 4-11

AVR block, 4-11AVR operation, 4-9

CCircuit boards

ACNA board, 1-4GDDD board, 1-4LDCC board, 1-4LTB board, 1-4NTB/3TB board, 1-4PSCD board, 1-4RTBA boards, 1-4TCCB board, 1-4

Configuration jumper, 4-5Configuration parameters, 4-5

DDiagnostic software, 1-6

EExciter data, 4-3

FFaults, 1-7Feedback offsets

EE.1508 VF1OF0, 4-8EE.1510 CF1OF0, 4-8EE.1513 VDCOF0, 4-8

FVROperation, 4-19Scaling, 4-19

GGDDD board, 2-8Generator data, 4-3Generator feedback, 4-6Generator inputs

Current transformer, 2-10Potential transformer, 2-9

Generator model jumper, 4-5Ground detector and diode faults

Configuration, 4-25Scaling, 4-25

HHMI, 1-8

IInput ratings

Auxiliary bus Input, 2-3Bus feed, 2-3Dc input power, 2-4PMG input, 2-3

LLTB board, 2-9

NNTB/3TB board, 2-9

OOffline checks, 5-6Online checks, 5-7Operator Interface

Switches, Meters, 5-8USC2000, IOS, 5-8

Ouput current rating, 2-4

2 •••• Index EX2000, PWM Digital Exciter GEH-6375

PP.T.U.V., 4-7Packaging

Enclosure, 2-2Environmental, 2-2

PFTD operation, 4-6Power checks, 5-4Power converter hardware

Ac and dc input devices, 2-6Dc link and dynamic discharge, 2-6IGBT and IAXS devices, 2-6Output contractor MDA, 2-7Output shunt SHA, 2-7

Prestart checksEnergization and simulator control, 5-2

Primary FCRConfiguration, 4-22Scaling, 4-22

PSCD board, 2-8PTCT board, 2-8PTFD scaling, 4-7

RRatings

Input ratings, 2-3REF1 Operation, 4-9

Autosetpoint block, 4-10Configuration, 4-10Scaling, 4-10

REF2Configuration, 4-19Operation, 4-18Scaling, 4-19

Regulator data, 4-4RTBA board, 2-9

SScaling, 1-7Simulator, 1-8

Operation, 6-4Scaling, 6-2

Software, 1-6Software Design, 3-2Standard functions

AVR, 3-3Firing block, 3-4FVR, 3-4OEL, 3-4UEL, 3-4

Standard software functions, 3-5

TTCCB board, 2-8Thermal model

Operation, 4-25Scaling, 4-26

Transducer outputs, 4-23

UUEL

Configuration, 4-14Curve, 4-14Operation, 4-13Scaling, 4-14

VVAR/PF control

Configuration, 4-17Operation, 4-17

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