logic pro

Scheme Testing ToolsLogicPro v1.5

User Manual

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OMICRON LogicPro

Manual Version: LogicPro.ENU.1 - Year 2001

© OMICRON electronics. All rights reserved.

This manual is a publication of OMICRON electronics GmbH.

All rights including translation reserved. Reproduction of any kind, e.g., photocopying, microfilming, optical character recognition and/or storage in electronic data processing systems, requires the explicit consent of OMICRON electronics.

Reprinting, wholly or in part, is not permitted. The product information, specifications, and technical data embodied in this manual represent the technical status at the time of writing and are subject to change without prior notice.

We have done our best to ensure that the information given in this manual is useful, accurate, up-to-date and reliable. However, OMICRON electronics does not assume responsibility for any inaccuracies which may be present.

The user is responsible for every application that makes use of an OMICRON product.

OMICRON electronics translates this manual from the source language English into a number of other languages. Any translation of this manual is done for local requirements, and in the event of a dispute between the English and a non-English version, the English version of this manual shall govern.

Table of Contents

TABLE OF CONTENTS

About This Guide ......................................................................................................................... 1

Before you start............................................................................................................................ 2Prerequisites................................................................................................................................ 2

How To Install OMICRON LogicPro............................................................................................. 3Software License Agreement....................................................................................................... 4

About Scheme Testing Tools Software........................................................................................ 5Introduction .................................................................................................................................. 5Overview...................................................................................................................................... 6

About OMICRON LogicPro .......................................................................................................... 9

Getting results............................................................................................................................ 13Test task .................................................................................................................................... 13Modes of operation .................................................................................................................... 13Test schemes available ............................................................................................................. 14What should be tested ............................................................................................................... 14How should it be tested ............................................................................................................. 15How the tests are performed ..................................................................................................... 16Test results analysis .................................................................................................................. 17Preparation for testing ............................................................................................................... 17Logic scheme selected ............................................................................................................. : 22Steps in testing .......................................................................................................................... 23

Getting Results in Animation Mode............................................................................................ 25Getting Results in Multiple Test Mode ....................................................................................... 36Getting Results in Scheme Test Mode ...................................................................................... 57

Switch-Onto-Fault ...................................................................................................................... 69Objective.................................................................................................................................... 69SOTF logic description .............................................................................................................. 69Fault locations............................................................................................................................ 71Test Cases................................................................................................................................. 71Hardware requirements ............................................................................................................. 72Automatic test sequence ........................................................................................................... 72Test object settings.................................................................................................................... 73

Remote-End-Opened................................................................................................................. 74Objective.................................................................................................................................... 74REO logic description ................................................................................................................ 74Fault locations............................................................................................................................ 76Test Cases................................................................................................................................. 76Hardware Requirements............................................................................................................ 76

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Automatic test sequence............................................................................................................ 77Test object settings .................................................................................................................... 78

Zone 1 Extension ....................................................................................................................... 79Objective .................................................................................................................................... 79Zone1 Extension logic description ............................................................................................. 79Fault locations ............................................................................................................................ 80Test Cases ................................................................................................................................. 81Hardware Requirements ............................................................................................................ 81Automatic test sequence............................................................................................................ 82Test object settings .................................................................................................................... 82

Load Encroachment................................................................................................................... 84Objective .................................................................................................................................... 84LE logic description .................................................................................................................... 84Fault locations ............................................................................................................................ 85Test Cases ................................................................................................................................. 86Hardware Requirements ............................................................................................................ 86Automatic test sequence............................................................................................................ 87Test object settings .................................................................................................................... 87

Breaker Failure Protection ......................................................................................................... 88Objective .................................................................................................................................... 88BFP logic description ................................................................................................................. 88Fault locations ............................................................................................................................ 89Test Cases ................................................................................................................................. 90Hardware Requirements ............................................................................................................ 90Automatic test sequence............................................................................................................ 91Test object settings .................................................................................................................... 91

Block Reclosing ......................................................................................................................... 93Objective .................................................................................................................................... 93BR logic description ................................................................................................................... 93Fault locations ............................................................................................................................ 94Test Cases ................................................................................................................................. 95Hardware Requirements ............................................................................................................ 95Automatic test sequence............................................................................................................ 96Test object settings .................................................................................................................... 96

Power-Swing-Blocking ............................................................................................................... 98Objective .................................................................................................................................... 98PSB logic description ................................................................................................................. 98Fault locations .......................................................................................................................... 100Test Cases ............................................................................................................................... 100Hardware Requirements .......................................................................................................... 101Automatic test sequence.......................................................................................................... 102Test object settings .................................................................................................................. 102

Table of Contents

Power-Swing-Tripping.............................................................................................................. 103Objective.................................................................................................................................. 103PST logic description ............................................................................................................... 103Fault locations.......................................................................................................................... 104Test Cases............................................................................................................................... 104Hardware Requirements.......................................................................................................... 104Automatic test sequence ......................................................................................................... 105Test object settings.................................................................................................................. 105

Loss-Of-Potential ..................................................................................................................... 106Objective.................................................................................................................................. 106LOP logic description............................................................................................................... 106Fault locations.......................................................................................................................... 107Test Cases............................................................................................................................... 108Hardware Requirements.......................................................................................................... 108Automatic test sequence ......................................................................................................... 109Test object settings.................................................................................................................. 109

Current Transformer Supervision............................................................................................. 111Objective.................................................................................................................................. 111CTS logic description............................................................................................................... 111Fault locations.......................................................................................................................... 112Test Cases............................................................................................................................... 113Hardware Requirements.......................................................................................................... 113Automatic test sequence ......................................................................................................... 114Test object settings.................................................................................................................. 115

Stub Bus Protection ................................................................................................................. 116Objective.................................................................................................................................. 116STP logic description ............................................................................................................... 116Fault locations.......................................................................................................................... 117Test Cases............................................................................................................................... 118Hardware Requirements.......................................................................................................... 118Automatic test sequence ......................................................................................................... 119Test object settings.................................................................................................................. 119

Single Pole Tripping................................................................................................................. 121Objective.................................................................................................................................. 121SPT logic description ............................................................................................................... 121Fault locations.......................................................................................................................... 123Test cases................................................................................................................................ 123Hardware requirements ........................................................................................................... 123Automatic test sequence ......................................................................................................... 125Test object settings .................................................................................................................. 125

Evolving Fault Logic................................................................................................................. 126Objective.................................................................................................................................. 126Evolving Fault logic description ............................................................................................... 126

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Fault locations .......................................................................................................................... 127Test cases ................................................................................................................................ 128Hardware requirements............................................................................................................ 128Automatic test sequence.......................................................................................................... 129Test object settings................................................................................................................... 129

Pole-Dead Logic ...................................................................................................................... 131Objective .................................................................................................................................. 131Pole-Dead logic description ..................................................................................................... 131Fault locations .......................................................................................................................... 132Test Cases ............................................................................................................................... 133Hardware Requirements .......................................................................................................... 133Automatic test sequence.......................................................................................................... 134Test object settings .................................................................................................................. 134

About This Guide

ABOUT THIS GUIDE

This guide provides a general overview of the OMICRON LogicPro software.

You will have reference information in the pop-up help in the various windows.

The sections under the heading “Before you Start”, “Prerequisites”, “How to install the OMICRON LogicPro”, and “Software License Agreement” deal with subjects you need to know before installing the OMICRON Performance Testing Software.

The section “About OMICRON Performance Testing Software” gives conceptual information about the tools for automatic testing of protection and control logic schemes in multi-functional protective relays.

The section “About OMICRON LogicPro” gives an overview and background information on different logic schemes and distance protection relays.

The section “Getting Results” describes in detail available modes of operation and provides step-by-step instructions for their use.

The section “Testing Relay Schemes” gives the principles of operation of individual schemes, test objectives, hardware requirements, test description and expected performance.

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BEFORE YOU START

PrerequisitesMinimum:

Pentium 90MHz

32 MB RAM

Windows 95, Windows NT4.0

(32-bit Windows)

Recommended:

Pentium 166MHz

64 MB RAM

Windows 95, Windows NT4.0 or higher

(32-bit Windows)

How To Install OMICRON LogicPro

HOW TO INSTALL OMICRON LOGICPRO

The OMICRON LogicPro software is delivered on a CD-ROM unless you have requested diskette installation.

When you are ready to install the OMICRON LogicPro.

1. Insert the CD in your CD-ROM drive to start the OMICRON LogicPro CD-Browser.

2. Close all other open applications.

3. Open Control Panel in Windows.

4. Open Add/Remove Programs.

5. Click on Install and follow the instructions.

6. Select the directory where you want OMICRON LogicPro installed.

7. Reboot your computer, before starting the OMICRON LogicPro.

If you need to make an installation with diskettesInsert Disk 1 in the floppy disk drive.

Follow the same procedure as for the CD-ROM installation...

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SOFTWARE LICENSE AGREEMENT

ScopeOMICRON LogicPro software as executable code in machine readable form on data carrier.

Content and scope of licenseOMICRON grants its customers the non-exclusive right (license) to use the software to control the OMICRON Test System Hardware purchased by him, and to use it in off-line mode. The right is not limited to a specific period of time. Property and copyright of the software or any of its parts will not pass to the customer.

The customer may not

make any modification to the software or have such modifications made by third parties,

install and run the software on computers other than those controlling OMICRON test equipment

give the product to third parties.

The software may be used only in conjunction with OMICRON Test System Hardware.

By means of information and agreements with employees who have access to the OMICRON software, as well as other suitable actions, the customer shall take care that the agreements will be complied with.

CopyrightThe software is property of OMICRON and is protected under copyright law.

WarrantyThe manufacturer agrees to remove all defects occurring during the first 90 days free of charge. A defect is defined as follows: The software does not have significant function, properties or does not meet performance specified in the user manual.

If any warranty claim is made, the original packing of the device must be used to return it in order to prevent the warranty claim from becoming void.

The manufacturer is not liable for lost profit, damages to saved data or other indirect or consequential damages.

About Scheme Testing Tools Software

ABOUT SCHEME TESTING TOOLS SOFTWARE

IntroductionThe electric power utility industry is going through significant changes due to deregulation, downsizing and free wheeling, etc. Power System Protection and Control departments face multiple challenges of their own:

reduced number of protection engineers

lack of experience

availability of very complicated, multifunctional microprocessor protective relays

availability of new operating principles in modern protective relays

availability of sophisticated relay testing technology

continuously increasing number of relay vendors and products

All of the above makes it extremely difficult for each particular utility to test and evaluate the new products. As a result not always the best technology for the application is used.

With the advancements in digital technology, new schemes and algorithms have been implemented in protection devices. It is becoming a challenge to utilities to benchmark relays. At the same time the more sophisticated testing tools allow digital software and hardware simulations and analog simulations for automatic benchmarking or commissioning and maintenance of microprocessor protection schemes and products. Microprocessor relays should be thoroughly tested to assure proper operation under a variety of network conditions.

Utilities can best insure optimal selection of the protection by benchmarking using appropriate tools. In addition, proper relay settings and operation for their particular complex problem need to be guaranteed by use of comprehensive test procedures.

It is always desirable to test and benchmark numerical algorithms and devices using worst case conditions.

This provides an added degree of confidence for the device to withstand the harsh environment encountered in the field. Thus, a product should employ detailed analysis and pass comprehensive testing prior to final approval.

Another improvement is to use data from the field to test protection systems. Modern microprocessor relays allow the user to collect disturbance data from the field.

This data can be used for evaluation of the protection system performance and for benchmark testing of new products, by directly comparing their performance under identical power system and fault conditions.

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OverviewOMICRON Scheme Testing Tools Software is a family of test programs designed to allow the user to evaluate in a quick and efficient way a multifunctional protection relay.

The OMICRON Scheme Testing Tools Software is a result oriented modular package of predefined standard procedures and software for performance relay testing. The tests are applicable to a wide variety of relays. It is not intended to replace the existing procedures and packages for automatic relay testing, but to complement them. The Overcurrent, Differential and Distance Testing programs are designed and implemented for the testing of different protection functions in single or multifuntional protective relays.

The Scheme Testing Tools Software provides for the automatic testing of logic schemes with different levels of complexity based on protection elements, that have already been tested by other OMICRON software products.

The OMICRON Scheme Testing Tools Software consists of a set of testing packages with different levels of complexity for the typical types of protective relays in each of the basic classes of protection systems:

Transmission line protection

Bulk transmission line protection

Distribution feeder protection

Transformer protection

Generator protection

Other

Each of these packages is subdivided into subsets based on the application of different protection principles and covers different cases, which correspond to a wide range of applications.

For example a Transmission Line Protection test package is divided in sub-packages that apply to the following types of transmission relays:

distance relays

current differential relays

directional comparison relays

phase comparison relays

The development of the different packages is prioritized based on the popularity of a certain protection principle, i.e. the number of protective relays of specific type manufactured and installed. In Transmission Line Protection without a doubt the most popular relay is the Distance Relay. Because of that, the distance principle Transmission Line Protection Testing Software is the first to be developed.

Considering the main goal of the Performance Testing to be the evaluation of applicability of a specific distance type multifunctional protective relay to different transmission line configurations and realistic power system conditions, the different groups of tests included in

About Scheme Testing Tools Software

the package are of the Dynamic State Test Type and Transient Simulation Test Type (depending on the requirements of each particular test).

Distance Transmission Line Protection Testing includes several basic groups of tests:

Tests of the basic analog input processing

Tests of the basic protection functions:

phase distance

ground distance

directional phase overcurrent

directional ground overcurrent

Tests of the additional protection functions

Tests of the basic communication based relay schemes

Tests of non-communication relay schemes

Tests of non-protection functions

Each group of tests listed above is divided in sub-groups, which are considered as independent test cases.

LogicPro is designed for the testing of the non-communication logic schemes of multifunctional distance relays.

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About OMICRON LogicPro

ABOUT OMICRON LOGICPRO

Since most of the protection functions of a transmission line protection relay are based on both the current and voltage measurements, the operation of the different protection elements is affected by many system conditions that may result in a relay maloperation.or non-operation.

Changes in the currents and voltages seen by the relay may affect the operation of the primary protection function of a transmission line protection relay - the distance elements. They may operate due to problems of the analog circuits or abnormal loading conditions. Switching from an open condition into a faulted line presents a different type of problems.

Figure 0-1: Forward looking distance protection zones with underreaching Zone 1

The transmission line distance protection relay with two forward looking zones, is shown in ( Figure 0-1, page -9 )

Different fault conditions and the operations of the breakers after a fault occurs have also to be considered in the design of the protective relays.

The requirements for improved stability of the power system during fault conditions result in the use of single pole tripping and reclosing. The performance of different relay protection elements related to this mode of operation are also covered by special logic schemes.

There are several different types of conditions that have to be considered:

Abnormal power system conditions include power swings or overloading of the transmission lines during a power system disturbance.

Failure of voltage or current transformers or the circuits connecting them to the analog inputs of the relay leads to a difference between the primary currents and

Substation 1 Substation 2

DistanceRelay

Zone 1Forward

Zone 2Forward

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voltages in the power system and the currents and voltages measured by the relay.

Breaker failure under fault conditions and non-fault conditions, for example overvoltage during light loading of long transmission lines, presents a different kind of problems to the distance relay.

To address all the requirements for speed and selectivity of operation during fault conditions, as well as to avoid maloperation under abnormal, but non-fault conditions, modern transmission line protection relays have multiple built-in logic schemes.

The communications based schemes, such as Permissive Overreaching or Blocking schemes are covered by the CommPro software.

LogicPro is designed for the testing of the more typical non-communications based logic schemes that still play a very important part and define the overall performance of distance transmission line protection relays.

Logic Pro test cases are divided in two groups as a function of the selected mode of tripping - single pole or three pole.

In both cases the following modules are available for testing of non-communications based logic schemes in modern distance relays:

Switch-Onto-Fault

Remote-End-Opened (Loss-of-Load)

Zone 1 Extension

Load Encroachment

Breaker Failure Protection

Block Reclosing

Power Swing Blocking

Power Swing Tripping

Loss-of-Potential (Voltage Transformer Supervision)

Current Transformer Supervision

Stub Bus Protection

The inputs and outputs of the CMC are programmed in such a way, that allows the testing of all the above schemes without any rewiring between the CMC and the test object.

If a Single Pole Tripping option is selected, three additional test modules become available:

Single Pole Tripping

Evolving Fault

Pole Dead Logic

About OMICRON LogicPro

Before running these three tests, the test engineer or technician will have to change the wiring according to the diagrams in the Hardware Requirements in order to be able to monitor the trip outputs for each individual phase.

The main advantages of the non-communication based logic schemes in transmission line protection relays are as follows:

They allow the relay to operate with high speed for conditions that challenge the operating principle of the main protection element - the distance protection

They ensure the stability of relay operation during abnormal power system conditions such as power swings or overloading of the transmission lines

They allow the relay to correctly detect the failure of a breaker to trip under fault or non-fault conditions, as well as to detect the opening of a remote breaker in order to accelerate the tripping of the local breaker

The relay can selectively trip one or all three phases for simple or evolving fault conditions

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Getting results

GETTING RESULTS

Test taskOMICRON LogicPro Software is a family of test tools for automatic testing of non-communication based logic schemes in transmission line protection relays. They include the most typical schemes, such as Switch-Onto-Fault, Breaker Failure protection and also cover some advanced features, like Current Transformer Supervision, etc.

The objective of this group of tests is to perform a number of dynamic tests to evaluate the most common non-communication based logic schemes used in modern transmission line relays with distance elements. Effects of load flow, fault resistance and remote end in-feed are not considered, because they don't affect the performance of these schemes, but the performance of phase and ground distance elements. These effects are subject to testing in other OMICRON test software. The assumption is made, that Zone 1, Zone 2 and reverse looking phase and ground distance elements have already been tested successfully.

The test object is a multi-functional distance relay with different logic schemes available. The assumption is that the relay under test is located at one end of the protected two ended transmission line. The power system environment, i.e. breaker status, pre-fault, fault and post fault current and voltages, are simulated by the CMC device.

During the testing of the different protection schemes in one of the modes of operation, all phase and ground distance zone settings remain the same. The only changes made are in the logic scheme selected for each individual subgroup of tests and the relay settings specific to the scheme under test.

It is recommended that other protection elements such as overcurrent or undervoltage should be disabled during these tests.

Modes of operationThe software can be used for different purposes and in different modes as described in detail later in the document.

The first mode is for benchmarking or complete evaluation purposes. In this case multiple logic schemes are selected in a “point-and-click” manner and the software automatically executes a series of predefined tests, measures the relay under test response, analyses the results and prepares the test report.

The second mode is for testing of a specific logic scheme, for example a Loss-of-Potential (Voltage Transformer Supervision) Scheme. In this case the software automatically executes a series of predefined tests required for the

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selected scheme, measures the relay under test response, analyses the results and prepares the test report.

The third mode of operation of the software is for training purposes. It includes multiple animated demonstrations of the sequence of events and the operation of different relay elements at each step of a test sequence. This tool is designed to help a protection or test engineer or technician with limited experience to understand the dynamics of the logic schemes operation and the functioning of the relay logic for different fault conditions and different substation or power system equipment performance.

Test schemes available The following most common logic Schemes are considered in LogicPro:

Switch-Onto-Fault scheme

Remote-End-Opened (Loss-of-Load) scheme

Zone 1 Extension scheme

Load Encroachment scheme

Breaker Failure Protection scheme

Block Reclosing scheme

Power Swing Blocking scheme

Power Swing Tripping scheme

Loss-of-Potential (Voltage Transformer Supervision) scheme

Current Transformer Supervision scheme

Stub Bus Protection scheme

Single Pole Tripping scheme

Evolving Fault scheme

Pole Dead Logic scheme

The logic for each of the above listed schemes is based on existing documents and may be implemented with modifications in specific products.

What should be testedThe testing of logic schemes is intended to evaluate the performance of the Test Object under different fault, system and substation conditions.

Different tests are designed to monitor the relay operation for the following fault conditions:

Zone 1 fault

Zone 2 fault on the protected line

Zone 2 fault outside of the protected line

Getting results

Single- phase-to-ground faults, three phase faults or evolving faults are applied depending on the requirements of the tested logic scheme.

Some of the logic schemes apply to the relay under test abnormal system conditions such as:

power swing

overload

overvoltage

How should it be tested

TEST METHODSThe testing of distance relays with built-in logic schemes can be performed in several different ways

USING FIXED INPUT STATUSIn this mode the testing of relays is performed with their inputs energized constantly and not synchronized with the test equipment. This approach can be used for testing of very simple relay functions. It does not adequately represent the dynamics of real life events and has very limited application for testing of modern microprocessor based transmission line protection relays.

Using this method the test engineer or technician can test just a simple scheme,

For example:

if a Switch-Onto-Fault scheme is tested,

the breaker status monitoring input of the test object will be continuously de-energized and when the fault currents and voltages are applied by the test device, this should result in switch-onto-fault.

It is obvious that this method can not be used for testing of more advanced logic schemes, such as Evolving Fault or Current Transformer Supervision.

USING SYNCHRONIZED INPUT STATUS In this mode the testing of relays is performed with their inputs energized as required by the dynamics of the simulated power system conditions and substation environment. It is considered as dynamic simulation, with multiple steps, each of which represents a different state - pre-fault, multiple fault and post-fault conditions.

This mode requires advanced test equipment that can be programmed to change the status of its analog and binary outputs, thus simulating not only changes of voltages and currents, but also breaker and other equipment status. The capability to change states as a result of test object operation is also necessary for the development and execution of test procedures for the testing of advanced logic schemes.

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This approach can be used for testing of very complicated relay functions. It allows for an adequate representation of the dynamics of real life events and can be used for advanced testing of modern microprocessor based transmission line protection relays.

For example:

using this method the test engineer or technician can test not only a simple Switch-Onto-Fault scheme, but also more advanced logic schemes, such as Permissive Overreaching Unblocking. In this case in the pre-fault condition a communication status signal (guard frequency available) will be simulated, which under fault conditions will change to a trip frequency Carrier Receive.

How the tests are performed The fundamental requirement in the LogicPro software is ease of use. The goal is to achieve maximum results with a minimum effort. That is why, the test configuration and execution efforts in most cases are limited to a “point-and-click” action.

The testing of logic schemes should be performed in a way that as closely as possible matches real life power system conditions. The sequence of steps in a test is different as a function of the requirements for the specific scheme and system condition.

For example, if the test is for a Switch-Onto-Fault scheme and the test conditions are breaker opened with a closing onto a fault, the sequence will include only three steps:

pre-fault with breaker in a opened position, nominal voltage and normal load current conditions

breaker closing with faults currents and voltages

post-trip condition with breaker opened, nominal voltage (assuming that bus voltage is applied to the relay) and no current

If a more complex scheme is tested, the number of steps will increase accordingly. For example if an Evolving Fault scheme is tested, the test will have to include the following steps:

pre-fault with breaker in a closed position, nominal voltage and normal load current conditions

initial fault condition with a single-phase-to-ground fault in the forward direction

evolving of the fault to a three-phase-to-ground fault

post-fault condition with breaker closed, nominal voltage and no load current conditions

The CMC Test Device is used to simulate both the analog and the digital signals received by the relay in the field.

The CMC inputs are used to monitor the operation of different relay elements as required by the scheme under test.

Getting results

To simplify the testing, the current and voltage levels are limited within the output range of the basic CMC module (no amplifiers are required). This way there is no need for the user to define the requirements for the CMC.

Test results analysisThe results from each test performed are automatically analyzed by the LogicPro software. The analysis is based on an expert system comparing the operating time of a combination of monitored protection elements that have picked-up during the test.

The operating time of the monitored protection elements is defined based on the protective relay manufacturer's technical specifications.

The results are displayed in a graphical format in the user interface and in detail in the automatically generated test report.

Preparation for testing

OVERVIEWAs mentioned earlier, the goal of the LogicPro software is to allow the testing of logic schemes and comparing the performance of different relays under identical test conditions.

During the testing of the previously listed schemes all phase and ground distance zone settings remain the same. The only changes made are in the logic scheme selected for each individual subgroup of tests and the relay settings specific to the scheme under test.

The fault currents and voltages are calculated based on a simple network model, since it is assumed that the basic distance functions have already been tested using more sophisticated test methods.

The following sections in this chapter describe the network model used for the calculation of the fault currents and voltages and the settings of the test object corresponding to this model.

Since the software has test and training modes of operation, the global test data is entered by the user only if one of the two test mode options has been selected.

NETWORK MODELBecause only a single end relay is tested, the network model used for calculation of short circuit currents and voltages for a Zone 1 or Zone 2 fault is a steady state single source fault analysis model.

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Figure 0-1: Test System Model

A 120 kV, 50 miles long line with delta configuration is used in the default model. The system is homogenous (i.e. source and line impedances have the same angle) and the Source to Line Impedance Ratio is SIR = 1.

The line impedance is 0.625 primary ohms per mile. The default line impedance angle is 75 deg.

The zero sequence impedance is 2.5 primary ohms per mile. The line zero sequence impedance angle is 75 deg.

The zero sequence to positive sequence impedance ratio is 4 and the zero sequence compensation factor KL

LINE AND SOURCE IMPEDANCES

If the rated current of the distance relay under test is 5 amperes, it is assumed that the CT ratio setting is

CT ratio = CTR = 2000/5 = 400

If the rated current of the distance relay under test is 1 ampere, it is assumed that the CT ratio setting is

CT ratio = CTR = 400/1 = 400

KL = (Z0 - Z1) / 3Z1 = (2.5 - 0.625) / 1.875 = 1.875 / 1.875 = 1.0

ZL primary = ZLp = 0.625 x 50 = 31.25 ohm

Z0L primary = Z0Lp = 2.5 x 50 = 125.00 ohms

50 miles

Substation A

Type Delta0.625 omhs/mile

120 kV

Getting results

It is assumed that the rated voltage of the distance relay is 120 V phase-to-phase and the VT ratio setting is

VT ratio = VTR = 1000/1 = 1000

Based on these CT and VT settings the secondary impedance is calculated using

ZL secondary = ZLs = 0.4 x 31.25 = 12.5 ohms

Z0L secondary = Z0Ls = 0.4 x 125.00 = 50.0 ohms

Because the source to line impedance ratio is 1, the source impedance in the network model will have the same values, i.e.

The source angle is 75 deg (default homogeneous system) and the K-factor

FAULT TYPE AND FAULT LOCATIONSThree-phase-to-ground faults or single-phase-to-ground faults are simulated at different locations along the model transmission line depending on the logic scheme under test.

Faults behind the relay are simulated for testing of Breaker Failure schemes initiated by another relay for an external fault.

TEST MODEConstant Source Impedance test mode is selected for all tests.

The fault incidence angle is 75 deg.

HARDWARE REQUIREMETSThe hardware requirements are different for the different communication based schemes. However, the system network model and fault locations selected result in fault currents and voltages that are within the range of 12.5 A, i.e. there is no

CTR / VTR = 400/1000 = 0.4

ZS = 12.5 ohms

KS = 1.0

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need for amplifiers. This simplifies the hardware configuration requirements for the testing.

Three phase voltages and currents are required from the CMC to the relay under test.

A different number of binary outputs of the CMC are programmed to simulate the relay environment as a function of the scheme under testing.

A different number of binary inputs of the CMC are programmed to monitor the relay operation as a function of the scheme under testing.

TEST OBJECT SETTINGSThe expected basic settings of the multifunctional relay under test associated with the communication based schemes are given below.

Getting results

Zone 1:

An 80% reach setting for Zone 1 is expected

In polar coordinates

In rectangular coordinates

The zero sequence compensation factor K0 = 1 at angle 0 deg

Zone 2:

A 120% reach setting for Zone 2 is expected

In polar coordinates

In rectangular coordinates

The zero sequence compensation factor K0 = 1 at angle 0 deg

The time delay for Zone 2 is 200 milliseconds.

Z1 = 0.8 x 12.5 = 10 ohms LV (secondary ohms)

Z1 angle = 75 deg

R1 = Z1 x cos 75 = 10 x 0.259 = 2.59 ohms LV

X1 = Z1 x sin 75 = 10 x 0.966 = 9.66 ohms LV

Z2 =1.2 x 12.5 = 15 ohms LV (secondary ohms)

Z2 angle = 75 de

R2 = Z2 x cos 75 = 15 x 0.259 = 3.88 ohms LV

X2 = Z2 x sin 75 = 15 x 0.966 =14.49 ohms LV

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If the distance relay settings are entered using the positive and zero sequence impedance for the different zones, the zero sequence impedance, resistance or reactance settings should be calculated based on the 50 ohm zero sequence secondary line impedance.

Logic scheme selected:This is the only setting/selection that changes between the different non-communication based schemes available.

Depending on the technical specifications of the test object (a multifunctional distance transmission line protection relay), this setting can be one of the following typical non-communication based logic schemes:

Switch-Onto-Fault scheme

Remote-End-Opened (Loss-of-Load) scheme

Zone 1 Extension scheme

Load Encroachment scheme

Breaker Failure Protection scheme

Block Reclosing scheme

Power Swing Blocking scheme

Power Swing Tripping scheme

Loss-of-Potential (Voltage Transformer Supervision) scheme

Current Transformer Supervision scheme

Stub Bus Protection scheme

Single Pole Tripping scheme

Evolving Fault scheme

Pole Dead Logic scheme

Steps in testingMultifunctional transmission line protection relays are very complex devices that require during testing adequate simulation of their operating environment, to ensure that they will perform correctly when installed in the field. There is a sequence of steps related to the testing of electromechanical, solid state or microprocessor based relays using different logic schemes for improved fault clearing. They depend on the goals of the test and the level of knowledge of the relay under test and it's operating principles

Getting results

Some of the steps are performed before the actual testing:

Learn About the Main Principles of the Test Object The user has to become familiar with the principles of operation of the test object (in this case a distance relay with preprogrammed logic schemes) and the sequence of events that result in an operation or non-operation. This information is usually available in the users manual of the tested relay. It will help to understand the results from the tests and their variation (if any) from the typical schemes used.

Learn About the Principles in the Test SequencesThe LogicPro software is based on the common industry understanding of logic schemes and some assumptions on the interface between the relay and the power system environment. The user has to become familiar with the basic principles implemented in the development of the test sequences.

This information is available in the LogicPro users manual and in an animated form in the LogicPro software.

If the user is familiar with the principles of the distance relay under test and the LogicPro software, he/she can proceed with the actual testing process.

For testing of multiple logic schemes in a new distance relay, the user should follow the step-by-step procedure described in Multiple Scheme Test Mode.

To test a specific logic scheme, the steps required are described in Single Logic Scheme Mode.

Determine the Correct Timer SettingsLogic schemes have different timer settings that significantly affect the test object performance.

The user has to select the appropriate settings for each logic scheme.

Analyze the Test ResultsIf the automatic analyses of the Test results indicates that some tests have failed, the user should check the required wiring, relay operating times, relay settings, relay logic diagrams, etc., to determine the reasons for the specific test failure.

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GETTING RESULTS IN ANIMATION MODE

When the test technician or engineer wants to become familiar with the principles of logic schemes included in the LogicPro software, he can use the software in the Animation Mode. The Loss-of-Potential (Voltage Transformer Supervision) Scheme is of specific interest.

The Hardware Requirements for this test and the objectives of each test executed by the software are also necessary to be checked.

To achieve this task, the following steps should be performed:

1. Start the LogicPro software by double clicking on the icon.

2. The splash screen will appear while the software is loading ( Figure 1-1, page -25 ).

I Start Animation Mode

Getting Results in Animation Mode

Figure 1-1: LogicPro software splash screen

3. The Main Selection window ( Figure 1-2, page -26 ) opens.

The Main Selection window is the primary tool of the graphical user interface for navigation through the software and for selection of the mode of operation.It changes dynamically depending on the user's actions.

In this case it will be used to select the Loss-of-Potential (Voltage Transformer Supervision) scheme and review the Principles of Operation, Hardware Requirements and Test Objectives.

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Figure 1-2: Main Selection window

At this stage it is not required to have a CMC test device connected to the computer for the software to run.

1. Click on the label Loss-of-Potential- (Voltage Transformer Supervision).

2. This will automatically open the Loss-of-Potential (Voltage Transformer Supervision) scheme control window. ( See Figure 2-1, page - 27 )

II Select Logic Scheme


Figure 2-1: Loss-of-Potential (Voltage Transformer Supervision) scheme control window.

The individual scheme control window has multiple control buttons that can be enabled or disabled depending on the actions of the user. Some of the control buttons used for the graphical user interface can also be visible or invisible at different times. This reduces the chances for an inappropriate action by the LogicPro software user.

To explore the principles of the LOP - Loss-of-Potential (Voltage Transformer Supervision):

3. Click on the Loss-of-Potential (Voltage Transformer Supervision) Logic Scheme control button to enable the Animation Mode of the scheme control window.

This action dynamically changes the scheme control window: ( See Figure 2-2, page - 28 )

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Figure 2-2: Loss-of-Potential (Voltage Transformer Supervision) scheme simplified logic diagram

4. The simplified logic diagram of a Loss-of-Potential (Voltage Transformer Supervision) communication aided scheme is displayed.

5. Three new control buttons appear in the window:

1 Ph Failure

Single Ph Fault

1 Ph Failure with Fault

6. On the bottom of the window a LEGEND with the symbols used in the graphics and animation is displayed ( See Figure 2-3, page - 29 ).


Note: It is recommended for users that do not have experience in power system or transmission line protection, to start by selecting the Slow speed option.

Figure 2-3: Animation control and legend

7. The abbreviations used in the simplified logic diagram are:

IOC - Instantaneous Overcurrent

V0 or V2 - Zero Sequence or Negative Sequence voltage

I0 or I2 - Zero Sequence or Negatiive Sequence current

The animation speed is controlled by an additional control object in the scheme control window. The default setting is Medium, which will be reset every time the form window has been unloaded. Once the Speed is changed it will remain the same for the next animation presentation.

Figure 3-1: Animation speed control frame

The frame with the animation speed options will be enabled and it's label will turn red when the animation mode is selected.

It includes three option buttons. Select a slow, medium or fast speed depending on your knowledge of the specific scheme displayed.

III Set Animation Speed

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1. Click on one of the available animation control buttons bellow the label saying “Click bellow to start Animations “.

For example, to watch the test sequence and relay operation for a single phase voltage circuit failure, click on the Single Ph. Failure.

During the animation each of the relay elements that are involved in the scheme logic is displayed with a different color depending on it's status.

When an element picks-up, it's color will change from black to red, and when it drops-out, the color will change back from red to black.

2. At the start of animation, a few additional changes occur:

A new Pause control button appears in the animation control frame (See bottom of ( Figure 2-3, page -29 ). It allows the user at any moment to stop the animation at the current state, so the current status of the simulation and relay performance can be reviewed in detail. It changes to Continue when clicked. If you want to proceed with the animation, click on Continue.

The status bar will display the name of the chosen fault scenario (See bottom of ( Figure 4-1, page -30 ) and ( Figure 2-3, page -29 )

A progress bar ( Figure 2-3, page -29 ) will appear, showing the progress of the animation

The Animated logic scheme Status Legend - 1.1 ( Figure 4-2, page -31 ), will appear

The Animated logic scheme Status Legend - 1.2 ( Figure 4-3, page -31 ), explains different stages of the process

Figure 4-1: Animated logic scheme operation Legend - (detail)

The Animated logic scheme Status Legend ( See Figure 4-2, page - 31 ) and ( Figure 4-3, page -31 ), which changes in accordance with the animation, shows the details at any moment of the process.

The Name of the state ( Figure 4-2, page -31 ) - the Pre-Fault condition is shown in red, while the State number (State 1) and the State Time is displayed in white

when it is a non-fault state or in red, when it is a fault state ( Figure 4-3, page -31 )

IV Start Animation


The Legend has three parts, each one showing:

The number of the State (sub processes) of the main process

A descriptive name of each State of the main process

Time of start of each State since the fault inception in ms. Pre-fault time in this case is a negative number

Figure 4-2: Animated logic scheme Status Legend - 1.1

Figure 4-3: Animated Status Legend - 1.2 (in different moment of the process)

3. A second timer to the right of the progress bar displays the current simulation time since the fault inception ( See Figure 4-4, page - 31 )

Figure 4-4: Animated simulation timer

4. To stop the animation at any time, click on Clear.

5. To return to the Main Selection window, click on Main.

1. To view the objective of the test included in the LogicPro software, click on the Test Objective command button.

2. The communication scheme control window will change as shown on ( Figure 5-1, page -32 ).

V View Test Objective

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Figure 5-1: Test objectives for a Loss-of-Potential scheme

3. In this case, there are two definition blocks:

The first one displays the general objective of the tests

The second one displays what tests are performed and the expected relay behavior

1. To view the Hardware Requirement click on the Hardware Requirements command button.

2. The logic scheme control window will change as shown on ( Figure 6-1, page -33 )

the required analog signals

the required binary signals

the wiring between the test device and the test object

the need for an external DC source

VI View Hardware Requirements


Figure 6-1: Hardware Requirements for Loss-of-Potential (Voltage Transformer Supervision) scheme tests

There are several options to print the information related to the communication scheme under consideration.

To Print:

1. Click on the Print option in the Menu bar on top of the Scheme Control window

2. Select the information to be printed

3. The Print dialog box will appear, allowing the user to specify a printer, if necessary.

The following options for printing ( See Figure 7-1, page - 34 ) are available:

1. the Scheme Logic as displayed during the animation

2. the Test Objective

3. the Hardware Requirements for the selected scheme

4. the complete Scheme Documentation (all options offered above) for the selected scheme

VII Print Options

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Figure 7-1: Loss-of-Potential (Voltage Transformer Supervision) - Print Options menu

To return to the Main Selection window, click on the Main button.

VIII Return to the Main Selection window

Getting Results in Multiple Test Mode

If 52b is used it should be wired only while executing the Echo Logic tests.

GETTING RESULTS IN MULTIPLE TEST MODE

The goal of the test is usually a benchmark test of the logic schemes of a new to the utility distance relay.

To perform such a test, the user should follow the step-by-step procedure described below.

Enter the required settings described in section Preparing the Test.

Note: It is recommended to set all available setting groups with different logic schemes, especially the mode of tripping-Single or Three Pole, and then during the test to switch between the setting groups as required by the test selected.

Check the required time settings for each scheme in the protection users manual.

1. Wire the Test Object (distance relay), DC power supply (if necessary) and the Test Device (CMC x56) according to the diagrams shown in Hardware Requirements for each of the individual schemes.

All logic schemes with Three Pole tripping mode can be tested without the need for changes in the wiring between the Test Device and the Test Object.

If Single Pole tripping is selected, a change in the wiring is required for the last three tests.

2. Connect the parallel cable between the Test Device and the Test Computer with LogicPro installed.

Note: Check if the relay uses 52a or 52b breaker status contacts. LogicPro simulates 52a breaker status.

I Set the Distance Relay

II Prepare the Hardware

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2. The splash screen will appear while the software is loading ( See Figure 1-1, page - 25 )



The analysis of the distance relay performance during the test is based on the expected operating times, of tested relay elements under different fault conditions.

The software is loaded using some default settings. However, if the user needs to change them based on the technical specifications of the distance relay under test, the default setting can be changed using the following steps:

To change the Default Time Settings:

1. Click on the Settings menu in the Menu bar on top of the Main Selection window.

2. Click on Time Test Settings... ( See Figure 4-1, page - 37 )

3. Review and change if necessary the operating times in the Change Settings window displayed in ( Figure 4-2, page -37 )

4. To apply the New Settings - press the Apply button.

5. To return the Default Settings - press the Default button.

6. To Cancel and Exit the window with the restored Default settings - Press the Cancel button.

7. To Exit the window with the entered Settings - Press the OK button.

Note: The default times for Zone1 (50 ms) and Zone2 (250 ms) faults, include a margin of 50 ms, i.e. Zone1 is set as instantaneous, while Zone2 is set with time delay of 200 ms.

III Start Logic Pro

IV Change Test Settings (optional)


Figure 4-1: Settings - Menu options

Figure 4-2: Change Time Test Settings.... window

To change the Default Line Impedance Settings:


2. Click on Line Impedance... ( See Figure 4-1, page - 37 )

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Figure 4-3: Line Impedance Settings - SECONDARY

3. Review and change the settings in the Change Settings window accordingly.

to review or edit the Secondary Settings - Leave the SECONDARY option checked ( See Figure 4-3, page - 38 )

to review or edit the Primary Settings - Select the PRIMARY option ( See Figure 4-4, page - 39 )

to review CT Ratio and PT Ratio Settings - Select the PRIMARY option. The window will display CT Ratio and PT Ratio options (grayed out). ( See Figure 4-4, page - 39 )

to edit CT Ratio and PT Ratio Settings - Select Nominal Values and then select the PRIMARY option. The window will display CT Ratio and PT Ratio options. ( See Figure 4-6, page - 41 )

To change the Zone 1 fault location (should be less than 100%) - enter the new number in the Fault Location field, as a percentage of the line impedance. This option is available both in Secondary and Primary.

4. To apply the New Setting - press the Apply button.

5. To return the Default Setting - press the Default button.

6. To Cancel and Exit the window with restored Default Settings - Press the Cancel button.

7. To Exit the window with the new entered Settings - Press the OK button.


The Line impedance Settings window ( Figure 4-3, page -38 ) displays the Secondary settings as Default.

Figure 4-4: Line Impedance Settings window - PRIMARY Settings

If PRIMARY Settings are displayed - the Secondary Settings will be disabled and grayed out.

Changes in the Primary Impedance are automatically reflected in the Secondary Impedance. When the Apply button is pressed - the program will apply the settings and automatically will recalculate the SECONDARY Settings and display the changes based on modification in the CT or PT ratio.

Note: Based on Secondary Line Impedance, the software automatically calculates the fault voltages and currents to be applied for Zone 1 and Zone 2 faults, when the user clicks on Apply or OK buttons.

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To change the Default Nominal Values (Voltage or Frequency) Settings:


2. Click on Nominal Values... ( See Figure 4-1, page - 37 )

3. Review and change if necessary the settings in the settings window accordingly.

to change the frequency, click on one of the two option buttons.

to change the voltage, chose between Ph-N or Ph-Ph.

to review or edit the Secondary Settings - Leave the SECONDARY option checked ( See Figure 4-5, page - 40 )

Figure 4-5: Nominal Values (Voltage/Frequency) Secondary Settings window

to review or edit the Primary Settings - Select the PRIMARY option ( See Figure 4-6, page - 41 )

to review or edit CT Ratio and PT Ratio Settings - Select the PRIMARY option. The window will display CT Ratio and PT Ratio options. The changes made here will be displayed grayed out in the Line Impedance Primary Settings window. ( See Figure 4-4, page - 39 )


4. To apply the New Setting - press the Apply button.

5. To return the Default Setting - press the Default button.

6. To Cancel and Exit the window with restored Default Settings - Press the Cancel button.

7. To Exit the window with the new entered Settings - Press the OK button.

Note: The user has an option to select to enter the voltage values as Phase-to-Neutral (default) or Phase-to-Phase.

Note: The default frequency setting is 60 Hz. When the user decides to change it for the first time, the software will ask, whether to leave it as a new default.

Figure 4-6: Nominal Values (Voltage/Frequency) Primary Settings window

If PRIMARY Settings are displayed - the Secondary Settings will be disabled and grayed out.

Changes in the Primary Currents and Voltages are automatically reflected in the Secondary. When the Apply button is pressed - the program will apply the settings and automatically will recalculate the SECONDARY Impedance Settings and display the changes based on modification in the CT or PT ratio.

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The Nominal Values Settings window ( See Figure 4-5, page - 40 ) displays the Secondary Settings for the currents and voltages as default.

To change the Default Breaker status Settings:


2. Click on Breaker / VT... ( See Figure 4-1, page - 37 )

3. Review and change if necessary the settings in the settings window accordingly. ( See Figure 4-7, page - 42 )

Figure 4-7: Breaker/VT Settings

The 3 Pole Trip/Close option is a default, and causes the following modifications in the Main selection window ( Figure 1-2, page -26 ):

the names of the last 3 logic schemes are displayed in red color

the Check Box controls in front of those schemes are disabled

To enable them: Select Single Pole Trip/Close option in the settings window ( Figure 4-7, page -42 ) instead of the default 3 Pole Trip/Close option.

To check the Faults Calculations:
1. Click on View in the menu in the Main Selection window.

Figure 4-8: View Menu in Main Selection window

2. Then click on View Faults Calculations ( See Figure 4-8, page - 43 ).

The Faults Currents and Voltages window opens. The calculations are grayed out, which shows that they can not be modified from here. The calculated Fault Currents and Voltages for Zone 1 Fault (Single Phase Faults and 3 Phase Faults), appears at the top of the window.( See Figure 4-9, page - 43 )

Figure 4-9: Faults Currents and Voltages window - top

The calculated Fault Currents and Voltages for Zone 2 faults (Single Phase Faults and 3 Phase Faults), appear at the bottom of the window ( See Figure 4-10, page - 44 ). The Vnom, Line Impedance and Source Impedance used for the calculations, are also displayed.

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The Settings are directly accessible from here, and when clicked, the Settings options window will appear on the top of the current window.

The changes made in the settings will be automatically reflected in the calculations of the Fault Currents and Voltages.

Figure 4-10: Faults Currents and Voltages window - bottom

To select individual schemes to be automatically tested 1. in the Multiple Test Mode, in the Main Selection window ( Figure 5-1,

page -45 ) click on the Check Box controls next to the name of the available schemes.

Before a selection is made, the Start Test command button is disabled

V Scheme Selection



Note: The names of the last three schemes are in red color and the Check Box controls in front of them are disabled when 3 Pole Trip is selected.

To enable them:

Click on Settings in the Menu.

Click on Breaker Settings ( See Figure 4-1, page - 37 )

Select Single Pole Trip/Close instead of 3 Pole Trip/Close option, in the window displayed

Click OK.

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The color of the names of the last three schemes will change to normal and the Check Box controls in front of them will be enabled.

As soon as the user clicks on any of the Check Boxes, the Main Selection window changes as shown in ( Figure 5-2, page -46 ).

Figure 5-2: Main selection window in Multiple Scheme Test Mode

Several changes occur as a result of the selection of at least one logic scheme: Based on the selected logic schemes the software displays Test Boxes with

the test cases associated with each selected scheme on the left side of the schemes’s Check Boxes. Each individual test case can be un-selected by it’s check box. ( See Figure 5-2, page - 46 ).

The Start Test command button is enabled

A Test Details window to display the status of the currently executed test with a legend underneath, appears on the right side of the Test Selection frame.

When all tests have been completed, the Test Details window will display the test summary.


If a mistake is made in the selection process:1. Click again on the same Check Box to select or un-select it.

2. Another option is to click on the Clear control button at the bottom of the window, that will result in displaying the default.

To exit the software at any time, just click on the Exit button.

To start the test, click on the Start Test command button.

1. As soon as the Start Test button is clicked, a Message Box ( See Figure 7-1, page - 47 ) will appear before the beginning of the test asking the test engineer or technician to check if the CMC is on.

If the CMC is on, just click Yes. Otherwise turn on the CMC and then click Yes, so that the tests may be performed.

The second option is to select No, which will disable the Start Test button and reset the selected test cases.

Figure 7-1: CMC On - Off

2. After the CMC is turned On, it is initialized and starts the preprogrammed and selected tests execution.

VI Start Multiple Test

VII Turn on the CMC

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1. Before the execution of each group of tests associated with a specific logic scheme, the user is reminded by the software ( Figure 8-1, page -48 ) to enable the logic scheme setting of the distance transmission line protection relay to match the expected by the test scheme.

Figure 8-1: Change communication scheme settings

2. If the scheme has already been enabled or after the change, proceed by clicking on the OK command button.

1. The running test will display a flashing yellow background. At the same time to the right of the selected test cases a small screen “TEST Status” will show a brief description of each test.

Note: Before the execution of an individual test the background of the Test Box is white.

2. Immediately after each individual test is completed, the result is analyzed and the background of the Test Box changes color.

If the relay operated as expected, the test is OK and the background turns green.

If there is any out of range operation the test fails and the Test Box background turns red.

VIII Change Logic Scheme Setting

IX Tests Execution


After the completion of all tests the results are visible as the background color of the Test Boxes.

If the Multiple Schemes test is successful, the background of all Test Boxes should be green.

The Test Details window at the same time displays a message “All tests are OK”.

If even one test has failed, the Test Details window displays a different message. It advises the user to check the relay logic, settings, etc., and the test objectives, and results in the Test report.

3. If necessary, the test engineer can preview the Test report, print it and save it as a file.

4. After all tests have been executed, the Print Report button in the Main Selection window is enabled so that the test report can be previewed and/or printed.

5. When the Print Report button is checked the Data Entry form is displayed as well.

1. Before the test results are previewed or printed, the user is asked to fill in the generic data for the test report.

Some of the entries are required and are supposed to be entered in the white fields.

The rest of the fields are optional and have gray background, as shown on ( Figure 10-2, page -50 ).

The software will keep the entered information for a specific field, if the Check Box in front of the field is checked.

As a default all Check Boxes are checked.

Figure 10-1: Global Data Entry form - detail

X Enter General Test Data

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Figure 10-2: Global Data Entry form

The software allows the user to save as a file for further use, the most frequently used information, (as shown in the detail ( Figure 10-1, page -49 )

2. When the Close button is pushed a message will appear, warning that the entered data related to the completed tests will be lost.

The measured operating times, the monitored protection functions for each individual test are stored in the memory of the computer and are available in the test report.

1. To preview these detailed test results, click on the Preview Report command button in the Data Entry form.

2. As a result, the Test Report window shown in ( Figure 11-1, page -51 ) and ( Figure 11-2, page -51 ) is displayed. You can scroll through the report as necessary.

XI Review Detailed Test Results


Figure 11-1: Preview General Data in the Test Report window

Figure 11-2: Preview report results in the Test Report window

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1. Click on Save As File button in the Data Entry window ( See Figure 10-2, page - 50 )

2. The Save As window will open allowing the user to choose directory and file format.

3. Unless changed, the File will be saved as Rich Text Format.

To print the results from the Multiple Test, click the Print Report command button in the Data Entry form ( Figure 10-2, page -50 ). The Print dialog box is displayed, allowing the user to specify a printer, if necessary.

To end the Multiple Test procedure:

1. Click on Close. This will take you back to the Main Selection window.

2. Click on Exit in the Main Selection window

OMICRON Logic Pro software offers brief on-line explanations for the major tasks to be performed. The Help Topics are accessible only through the Menu in the Main Selection window. To see the different topics, click on Logic Pro Help Topics... ( See Figure 15-1, page - 53 )

XII Save Tests Results

XIII Print Test Results

XIV End Test

XV Help


Figure 15-1: Help Options under the Menu in the Main Selection window

The help window opens with brief overview of the software, displayed in the front page. ( See Figure 15-2, page - 53 ).

Figure 15-2: LogicPro Help window displayed

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To view the available Help Topics, click on HelpTopics in the menu of the Help window. ( See Figure 15-3, page - 54 )

Figure 15-3: LogicPro Help Topics

The full topic, or a selection of the content of the topic, can be printed from that window as well. Some of the Settings provide additional topics with in detail instructions as follows.

The Animation Mode offers:

Overview

Animation Scheme

Animation Controls

Animation Speed

The Test Mode offers:

Overview

Fault Currents/Voltages

Select Test Cases

Start Selected Tests

The Settings offer:

Breaker/VT

Time Test Settings

Line Impedance Settings

Nominal Values Settings


The Printing Options offer:

Overview

Data Entry

Print Preview

Print Test Results

When a specific topic is selected and displayed, its’ name is shown on the top of the Help window and appears disabled in the HelpTopic’s menu. ( See Figure 15-4, page - 55 ).

Figure 15-4: Help Topics -detail

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GETTING RESULTS IN SCHEME TEST MODE

The goal is to test a single communication aided scheme of a distance relay.

To perform such a test, the user should follow the step-by-step procedure described below.

To achieve this task, the following steps should be performed:

.

Enter the required settings described in section Preparing the Test

1. Wire the Test Object (distance relay), DC power supply (if necessary) and the Test Device (CMC x56) according to the diagrams shown in Hardware Requirements for the communication aided scheme to be tested.

2. Connect the parallel cable between the Test Device and the Test Computer with LogicPro installed.

Note: Check if the relay uses 52a or 52b breaker status contacts. LogicPro simulates 52a breaker status only.

Since a single scheme is tested, use the Hardware Requirements for the selected scheme.

I Set the Distance Relay

II Prepare the Hardware

Getting Results in Scheme Test Mode


2. The splash screen will appear while the software is loading ( See Figure 1-1, page - 25 )



The analysis of the distance relay performance during the Single Scheme test is based on the expected operating times under different fault conditions.

The software is loaded using some default settings. However, if the user needs to change them based on the technical specifications of the distance relay under test, the default setting can be changed using the steps described in the Multiple schemes test chapter ( See Figure 4-2, page - 37 )

( See also “Change Time Test Settings.... window ,” page -37 )

(See also “Line Impedance Settings - SECONDARY,” page -38.)

( See also “Line Impedance Settings window - PRIMARY Settings ,” page -39 )

( See also “Nominal Values (Voltage/Frequency) Secondary Settings window ,” page -40 )

( See also “Nominal Values (Voltage/Frequency) Primary Settings window ,” page -41 )

( See also “Breaker/VT Settings ,” page -42 )

III Start Logic Pro

IV Change Test Settings (optional)

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1. To select individual schemes to be automatically tested in the Scheme Test Mode, in the Main Selection window ( Figure 5-1, page -58 ) click on the scheme name to select one of the available schemes.


2. Before a selection is made, the Start Test command button remains disabled.

3. As soon as you click on one of the Scheme Name Box, the Individual Scheme Control Window will open as shown in ( Figure 5-2, page -59 ).

V Scheme Selection


Figure 5-2: Loss-of-Potential (Voltage Transformer Supervision) scheme individual control window.

4. If you want to return to the Main Selection window at any time, just click on the Main button.

.

LogicPro allows the user to select from the available tests before starting the tests execution.Click on Select Test Case in the Test Options frame to Start Test Procedures.

VI Start Scheme Test

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Several changes occur in the Scheme Control Window as a result of the Select Test Case action:1. Based on the selected communication scheme the software displays several

Test Boxes with the test cases associated with the selected scheme, on the left side of the graphical display window in a Test Options frame. Each individual test case can be unselected by it’s own check box. ( See Figure 6-2, page - 60 ).

2. The hardware requirements are displayed in the graphical window

3. A Test Status window with a legend underneath, appears on the right side of the graphical window.

4. The Select Test Case command button is disabled

5. A Start Test command button appears

6. The Fault Currents and Voltages for the first selected test case are displayed on the top of the window ( See Figure 6-1, page - 60 )

Figure 6-1: Faults Currents and Voltages for the first selected test case

Figure 6-2: Scheme Mode Control Window before test execution


To continue with the tests execution, in the Test Options frame: If necessary, unselect a test case to prevent it’s execution (all Test Cases are

selected as default).

Click on Start Test button to Start Selected Tests.

Click on Start Test button to Start Selected Tests.

1. As soon as the Start Test button is clicked, a Message Box ( See Figure 7-1, page - 61 ) will appear before the beginning of the test asking the test engineer or technician to turn the CMC On.

If the CMC is on, just click Yes. Otherwise turn on the CMC and then click Yes, so that the tests may be performed.

The second option is to select No, which will disable the Start Test button and reset the selected test cases.

Figure 7-1: CMC On - Off

2. The CMC is initialized and starts the preprogrammed tests execution.

VII Turn on the CMC

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1. Before the execution of the selected test cases associated with the selected logic scheme, the user is reminded by the software ( Figure 8-1, page -62 ) to enable the logic scheme, of the distance transmission line protection relay to match the expected by the test scheme.

Figure 8-1: Change communication scheme settings

2. After the change of the scheme setting, proceed by clicking on the OK command button.

1. The running test will display a flashing yellow background.

Note: Before the execution of an individual test the background of the Test Box is white.

2. Immediately after each individual test is completed, the result is analyzed and the background of the Test Box changes color.

If the relay operated as expected, the test is OK and the background turns green.

If there is any out of range operation the test fails and the Test Box background turns red.

VIII Change Communication Scheme Setting

IX Tests Execution


After the completion of all tests the results are visible as the background color of the Test Boxes. If the scheme test is successful, the background of all Test Boxes should be green.

The Test Details window at the same time displays a message “All test are OK”.

If even one test has failed, the Test Details window displays a different message. It advises the user to check the relay logic, settings, etc., and the test objectives, and results in the Test report.

3. If necessary, the test engineer can preview the Test report, print it and save it as a file.

4. After all tests have been executed, the Print Report button in the Main Selection window is enabled so that the test report can be previewed and/or printed,

5. When the Print Report button is pushed the General Data Entry form is displayed as well.

1. Before the test results are previewed or printed, the user is asked to fill in the generic data for the test report.

Some of the entries are required and are supposed to be entered in the white fields.

The rest of the fields are optional and have gray background as shown on ( Figure 10-1, page -64 ).

The software will keep the entered information for a specific field, if the Check Box in front of the field is checked.

As a default all Check Boxes are checked.

X Enter General Test Data

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Figure 10-1: Global Data Entry form

2. If the Close button is pushed a message will appear, warning that the entered data related to the completed tests will be lost.

The most frequently used data can be saved for future use, by clicking the Save General Report Data in the Data Entry form.( See Figure 10-1, page - 49 )

The measured operating times of each individual test are stored in the memory of the computer and are available in the test report.

1. To preview these detailed test results, click on the Preview Report command button in the Data Entry form.

2. As a result, the Data Entry window shown in ( Figure 11-1, page -65 ) and ( Figure 11-2, page -65 ) is displayed. You can scroll through the report as necessary.

XI Review Detailed Test Results


Figure 11-1: Preview General Data in Test Report window

Figure 11-2: Preview test results in the Test Report window

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1. Click on Save As File button in the Data Entry window ( See also “Global Data Entry form ,” page -64 )

2. The Save As window will open allowing the user to chose directory and file format.

3. Unless changed the File will be saved as Rich Text Format.

To print the results from the test, click the Print Report command button in the Data Entry form on ( Figure 10-1, page -64 ). The print dialog box is displayed, allowing the user to specify a printer, if necessary.

To end the Scheme Test procedure:

1. Click on Close. This will take you back to the Scheme Mode Control window

2. Click on the Main button in the Scheme Mode Control window. This will take you back to the Main Selection window

3. Click on Exit in the Main Selection window

OMICRON LogicPro software offers brief on-line explanations for the major tasks to be performed. The Help Topics are accessible only through the Menu in the Main Selection window.

XII Save Tests Results

XIII Print Test Results

XIV End Test

XV Help


Figure 15-1: Help Options under the Menu in the Main Selection window

To open the Help window with the available help topics, click on Logic Pro Help Topics.... ( See Figure 15-1, page - 67 ).

To check the different Help Topics, click on HelpTopics in the menu of the help window.( See Figure 15-2, page - 67 ).

Figure 15-2: LogicPro Help Topics

The full topic, or a selection of the content of the topic, can be printed from that window as well.

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Switch-Onto-Fault

SWITCH-ONTO-FAULT

ObjectiveThe objective is to perform dynamic test to evaluate the Switch-Onto-Fault (SOTF) scheme of a distance relay, as a function of the fault location, type of fault, and breaker status conditions.

The Test Object is a multifunctional distance relay with SOTF scheme at one end of the line. The single phase or three phase breaker status signals are generated by the CMC.

SOTF logic description(SOTF - Switch-On-To-Fault Logic)

Switch-On-To-Fault Logic in distance relays is required under different fault conditions while closing the breaker with a permanent fault on the protected line. The fault can be a result of natural events or human errors (a very typical one is when the grounding switches have been left closed after the line or breaker maintenance has been completed.

The location of the voltage transformers is very important, since it will affect the behavior of the distance relay. When a fault occurs during normal operation of the line, the voltage drops as a function of the type of fault and the fault location.

For close in faults, the voltage in the faulted phase will be close to zero, that will make more difficult the operation of the distance element. A cross-polarized distance relay will use the voltages in the healthy phases for polarizing.

The worst case is a close-in three phase fault that will result in voltage levels close to zero in all three phases. Cross polarizing does not help under these conditions. Simple distance relays will have difficulty operating under these conditions. That is why memory polarized relays were invented. In microprocessor relays they will store several cycles of voltage samples that will be used for polarizing in the case when the fault voltages are close to zero.

The situation is quite different when switching-on-to-a fault. This is when the location of the voltage transformers becomes very important. On transmission lines the voltage transformers are in many cases located on the line. When the line is opened from both ends, there will be no voltage measured by the distance relay, that means that if the breaker is closed with the grounding switches on, there are no voltage samples stored in the relay memory, and the memory polarized distance elements will not operate.

This problem is solved by the Switch-On-To-Fault Logic. It is provided in order to ensure high speed fault clearing immediately following line energization. It is enabled for a short period of time after the breaker closing. The breaker has to be open for a relay specific or user defined time before the SOTF logic is turned on. This is detected typically by monitoring of the breaker auxiliary contacts. If the

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voltage transformers are located on the line side of the breakers, the absence of voltage in all three phases can be used to detect the line open condition. At the same time all three phase currents shall be below the level defined by a low undercurrent setting.

The Switch-On-To-Fault Logic enables the operation typically of non-directional overcurrent elements. However, many modern microprocessor based relays allow the user to define which protection functions will be operational during the time that the Switch-On-To-Fault logic is enabled.

A similar logic is used during the reclosing cycle of a distance relay when the relay is connected to line-side voltage transformers. This logic is called Trip-On-Reclose and follows the same ideas as in the SOTF logic.

Since the SOTF logic always operates for a permanent fault condition, it will trip three phase regardless of the type of fault.

A transmission line can be energized from each end. The grounding switches can be closed at the remote end of the line when the breaker is closed at the local end. In this case the line should be trip instantaneously, without any time delay, other than the operating time of the protection elements enabled by the SOTF logic.

Simplified diagram of the Switch-On-To-Fault logic is shown in ( Figure 0-1, page -70 ).

Figure 0-1: Simplified SOTF logic diagram

Trip

Manual Close

Breaker Open

Fault Detect

IOC

0

0

Z

tpu

0

Switch-Onto-Fault

Fault locationsFaults are simulated at 2 locations along the model transmission line:

The fault locations are shown on ( Figure 0-2, page -71 )

Figure 0-2: Fault location for the testing of the SOTF logic

1. Zone 1 single-phase-to-ground fault and three-phase-to-ground fault at 50% of the line length

2. Zone 2 three-phase-to-ground fault at 100% of the line length

Test CasesThe Switch-Onto-Fault (SOTF) scheme is tested for the following fault conditions:

1. For Zone 1 single-phase-to-ground fault: - the relay should trip three phase without time delay. Switch-On-To-Fault alarm should be detected if available in the relay under test.

2. For Zone1 three-phase fault: - the relay should trip three phase without time delay. Switch-On-To-Fault alarm should be detected if available in the relay under test.

3. For Zone2 three-phase fault: - the relay should trip three phase without time delay. Switch-On-To-Fault alarm should be detected if available in the relay under test.


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA250% 100%

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Note: If the relay uses a 52b breaker status contact, it should not be wired.

Hardware requirements

Figure 0-3: Hardware wiring diagram for testing of the SOTF logic.

The CMC test device is programmed to simulate the substation and power system environment through the analog and binary outputs. At the same time the binary inputs are used to monitor the operation of the test object.

A typical wiring diagram for the SOTF logic test is shown ( Figure 0-3, page -72 )

Automatic test sequenceThe automatic test sequence will have several steps shown with animation in the LogicPro software. Only the steps related to the relay at the local end are executed.

IA

IB

IC

IA

IB

IC

ININ

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs

+ DC - DC

+ DC - DC

+ DC - DC

Out 1

Out 2

Out 3

52aA

52aB

52aC

DigitalInputs

RelayOutputs

In 1 Trip A

In 3

In 2 Trip B

Trip C

In 4 3Ph Trip

VN VN

Switch-Onto-Fault

Test object settingsThe expected basic settings of the multifunctional relay under test associated with the SOTF logic are given in the common section at the beginning of this document.

The only setting that has to be changed for this group of test cases is the enabling of the SOTF logic.

Three relay inputs have to be programmed as single phase normally open (52a) breaker status monitoring inputs.

Three relay outputs should be programmed to trip phase A, B and C accordingly.

Single Pole Tripping should be enabled. The Phase A Trip and SOTF or 3Phase Trip signals are monitored by the CMC.

Since there are specific details in the implementation of SOTF logic in different distance relays, they have to be considered during the preparation for the testing based on the recommended settings in the users manual for the test object

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REMOTE-END-OPENED

ObjectiveThe objective is to perform dynamic test to evaluate the Remote End Opened (REO) scheme of a distance relay, as a function of the fault location, type of fault, and healthy phase current conditions.

The Test Object is a multifunctional distance relay with REO scheme at one end of the line.

REO logic description(REO - Remote-End-Opened)

High speed tripping of faults located anywhere on a transmission line is a requirement that results in improved system stability and reduced effect of the fault on different utility customers. However, the most widely used distance protection relays use a step distance scheme that usually ensures high speed fault clearing only for faults inside of Zone 1 of the protection, i.e. up to 85 - 90% of the line length. Faults outside of Zone 1 are cleared from one end of the line with a time delay.

Communication based permissive and blocking scheme are used in order to overcome this deficiency of the distance type relays. Since they are based on the exchange of signals between the relays at the ends of the line, they require the installation and maintenance of communication channels. If the communication channel fails or the signal transmission is affected by the fault, the accelerated fault clearing will not be achieved.

A solution to this problem is the Remote-End-Opened logic in modern microprocessor based distance relays. This logic is designed to detect the opening of the remote end breaker after the relay there has detected a fault in Zone 1. Since under normal system conditions there will be a three phase load current flowing through the line, the trip of the remote end breaker will be detected by the load current in the healthy phases going to zero.

The Remote-End-Opened accelerated trip logic is shown in ( Fig. 0-4, page - 75). Since the logic is based on detection of no current in a healthy phase, this logic provides fast fault clearance for all types of faults, except three phase faults (in this case opening of the remote end will not result in current of any phase going to zero).

The main advantage of this logic scheme is that it does not require a communications channel. In some relays this logic can be continuously enabled or enabled only when the communication channel has failed.

Any fault located within the reach of Zone 1 at the remote end will result in fast tripping of that circuit breaker. For a Zone 2 fault with a source at the remote end, the remote breaker will be tripped in Zone 1 time by the remote relay and the local

Remote-End-Opened

relay can recognize this by detecting the loss of load current in the healthy phases. This, combined with operation of the Zone 2 element at the local end will result in the tripping of the local circuit breaker.

In order for the logic to function in the case of single-phase-to-ground, phase-to-phase or two-phase-to-ground faults, the logic must detect the availability of three phase load current prior to the fault.

The loss of load current opens a window during which time a trip will occur if a Zone 2 element operates.

The accelerated trip is delayed by a certain time (about one cycle) in order to prevent initiation of a loss of load trip due to circuit breaker pole discrepancy occurring for clearance of an external fault. The local fault clearance time is determined by the maximum Zone 1 trip time, the breakers trip time and the load current level detector reset time, as well as the Remote-End-Opened logic time delay

Note that loss of load tripping is only available where 3 pole tripping is used.

Simplified logic for the Remote-End-Opened scheme is shown in ( Figure 0-4, page -75 ).

Figure 0-4: Simplified diagram for the Remote-End-Opened logic

Trip

Ia

Ib

Ic

Substation BSubstation A

Zone 1

Triptdo

tpu3 Ph LoadCurrent

Zone 2

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Fault locationsFaults are simulated at two location on the substation bus:

1. Internal single-phase-to-ground fault - at 50%

2. External Zone 2 single-phase-to-ground fault

3. Internal Zone 2 single-phase-to-ground fault

Figure 0-5: Fault locations for testing of the Remote-End-Opened logic

The three fault locations are shown on ( Figure 0-5, page -76 ).

Test CasesThe Remote-End-Opened (REO) scheme is tested for the following fault conditions:

1. For Zone 1 single-phase-to-ground fault: - the relay should trip with Zone 1

2. For External single-phase-to-ground Zone 2 fault: - the relay should not trip

3. For Internal single-phase-to-ground Zone 2 fault: - the relay should trip with REO time

4. For External single-phase-to-ground Zone 2 fault with zero current in a healthy phase: - the relay should not trip

Hardware RequirementsThe CMC test device is programmed to simulate the substation and power system environment through the analog and binary outputs. At the same time the binary inputs are used to monitor the operation of the test object.

A typical wiring diagram for the Remote-End-Opened logic test is shown in:

( Figure 0-6, page -77 ).


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA2

50% 100%100%Ext

Remote-End-Opened

The CMC simulates the status of the normally open auxiliary contacts of the breaker, and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.

The potential free relay output of the CMC has one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of the relay input is connected to (-) DC.

The Trip output of the relay is wired to the Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and together with the monitored Remote-End-Opened output evaluate the correct phase selection and operation of the Remote-End-Opened logic during the different fault tests.

Figure 0-6: Hardware wiring for testing of the Remote-End-Opened logic


IA

IB

IC

IA

IB

IC

ININ

VA VA

VBVB

VC VC

DigitalInputs

RelayOutputs

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs+ DC - DCOut 1 52a

In 1 Trip

VN VN

In 2 REO

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Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Remote-End-Opened logic are given in the common section at the beginning of this document.

The only setting that has to be changed for this group of test cases is the enabling of Remote-End-Opened logic and the associated with it manufacturer recommended settings.

One relay input has to be programmed as a normally open (52a) breaker status monitoring input.

One relay output is programmed as Trip, while a second one is set to indicate the operation of the Remote-End-Opened logic

Since this logic operates only for 3 Phase Trip only, Single Pole Trip should be disabled.

Zone 1 Extension

ZONE 1 EXTENSION

ObjectiveThe objective is to perform dynamic test to evaluate the Zone 1 Extension scheme of a distance relay, as a function of the fault location, type of fault, and healthy phase current conditions.

The Test Object is a multifunctional distance relay with Zone 1 Extension scheme at one end of the line.

Breaker Status and Reclosing Status signals are simulated by the CMC.

Zone1 Extension logic description(Z1Ext - Zone 1 Extension)

One of the main goals in any transmission line protection system is to achieve as short as possible fault clearing time regardless of the location of the fault. Since there are multiple factors that affect the accuracy of the relay distance elements, Zone 1 coverage is usually limited to about 85% of the line length, leaving the protection of the remaining 15% to the Zone 2 elements.

Different communications based schemes are implemented in order to achieve protection for any fault on the line without the Zone 2 time delay. However, they are channel dependent, and in the case of communications failure will not provide the desired instantaneous operation.

A solution to this problem is given by an extended Zone 1 distance protection function. The idea is to extend the reach of Zone 1 to more than 100% of the line length when a fault occurs initially on the protected transmission line. This way any fault on the line will be cleared instantaneously at both ends without the need for a communication channel between the two relays at both ends of the line. The only problem with this logic is that the relay may also trip for some external faults. In order to reduce the chances of tripping the unfaulted line for a long period of time, the extended Zone 1 is disabled after the first reclosing shot, thus providing time coordination with the Zone 1 distance elements protecting lines, or other power system equipment at the remote substation.

The possibility for the extended Zone 1 operation for external faults is significantly reduced by the infeed from other sources at the remote substation. The case when overreaching for external faults is an issue are if there is a weak source or no source at the remote end.

In order to further reduce the possibility for undesired relay operation, in some modern microprocessor based relays the user has an option to enable the extended Zone 1 scheme only when there is a communication channel failure.

On ( Figure 0-7, page -80 ) is shown a simplified diagram of the Zone 1 Extension logic that should be enabled when testing the relay under different fault conditions.

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Figure 0-7: Simplified Zone 1 Extension Tripping logic diagram


1. Internal single-phase-to-ground fault - at 50%

2. External Zone 2 single-phase-to-ground fault

Internal Zone 2 single-phase-to-ground fault

The three fault locations are shown on ( Figure 0-8, page -81 )

Ia

Ib

Ic


Zone 1 Ext

Zone 1

Z2t

Z1 Ext AR

Z 2

Zone 2

Zone 1 Extension

Figure 0-8: Fault location for the testing of the Zone 1 Extension logic

Test CasesThe Zone 1 Extension scheme is tested for the following fault conditions:

1. For Zone1 single-phase-to-ground fault: - the relay should trip with Zone 1 time.

2. For External single-phase-to-ground Zone2 fault with unsuccessful reclosing: - the relay should trip with no delay, reclose and does not trip after the second fault.

3. For Internal single-phase-to-ground Zone2 fault with successful reclosing: - the relay should trip with no delay and reclose


A typical wiring diagram for the Zone 1 Extension logic test is shown on ( Figure 0-9, page -82 )

The CMC simulates the status of the normally open auxiliary contacts of the breaker (52a) and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation. It also simulates the operation of an external autoreclosing device (AR)

Both potential free relay outputs of the CMC have one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of each relay input is connected to (-) DC.

The Trip output of the relay is wired to a Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA2

50% 100%100%Ext

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evaluate the correct phase selection and operation of the Zone 1 Extension logic during the test.

A second input of the CMC monitors the Zone 1 Extension operation indication from the relay.

Figure 0-9: Hardware wiring diagram for testing of the Zone 1 Extension logic


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Zone 1 Extension logic are given in the common section at the beginning of this document.

The only setting that has to be changed for this group of test cases is the enabling of Zone 1 Extension logic.

IA

IB

IC

IA

IB

IC

I NIN

VA VA

VBVB

VC VC

DigitalInputs

RelayOutputs

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs


In 1 Trip

VN VN

In 3 Z1X

Zone 1 Extension

One relay input has to be programmed as a normally open (52a) breaker status monitoring input. A second relay input should be programmed to monitor external Auto Reclosing status.

One relay output should be programmed to Trip, while a second one should be programmed to provide a Zone1 Extension operation.

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LOAD ENCROACHMENT

ObjectiveThe objective is to perform dynamic tests to evaluate the performance of a distance relay, as a function of the load condition, breaker status, fault location, type of fault, and selected mode of operation for different system conditions.

The Test Object is a multifunctional distance relay. The performance of the relay at one end of the line is tested.

Breaker status signals for each of the three phases of the breaker are simulated by the CMC.

LE logic description(LE - Load Encroachment)

Distance functions based transmission line protection is required to operate correctly under very different power system conditions. A very important criteria is the correct relay operation for very heavy load conditions, since this can result in sequential tripping during a power system disturbance, leading to further deterioration of the conditions and total system collapse.

The changes of the load impedance measured by the relay are very slow compared to the changes during a short circuit or power swing in the system. Another very important characteristic of this process is that there is no significant change in voltage.

The characteristics of the distance elements are important from the perspective of the load impedance entering into the backup protection zones - usually Zone 3. Quadrilateral characteristics or combinations of mho characteristics with load blinders are typically used to allow backup protection of long lines, while avoiding the load impedance entering into the distance zone.

At the same time, the protective relay should be able to trip for fault conditions that occur simultaneously with the maximum load conditions, or for high impedance faults that may result in a fault current lower than the maximum load condition.

Coverage for such fault conditions is typically based on the quadrilateral characteristic for ground distance elements or directional ground overcurrent protection for very high impedance faults

( Figure 0-10, page -85 ) and ( Figure 0-11, page -85 ) show the apparent load impedance seen by distance relays with a quadrilateral characteristic or mho characteristic with a Load Blinder.

Load Encroachment

Figure 0-10: Load Encroachment in case of Mho characteristic with blinders

Figure 0-11: Load Encroachment in case of Quadrilateral characteristic

Fault locationsFaults are simulated at one location along the model transmission line:

1. Zone 1 single-phase-to-ground fault at 50% of the line length with overload

2. High impedance single-phase-to-ground fault

Z2

Z1

Z3

No Operation

Z2

Z1

Z3

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Figure 0-12: Fault locations for Load Encroachment logic


Test CasesThe distance relay is tested for the following system and fault conditions:

1. For a maximum load condition (40% overload) the relay distance elements should not trip

2. For a maximum load condition (40% overload) followed by Zone1 single-phase-to-ground fault: - the relay should trip single pole with Zone1 time after the fault inception

3. For high impedance single-phase-to-ground fault: - the relay should trip with ground overcurrent protection time delay


A typical wiring diagram for the Load Encroachment test is shown in ( Figure 0-13, page -87 ).

The CMC simulates the status of the normally open auxiliary contact for the breaker (52a) and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.

A potential free relay output of the CMC has one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of the relay input is connected to (-) DC.

The Trip output of the relay is wired to a Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and evaluate the correct operation of the relay logic during the load encroachment test.


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA2

50%

Load Encroachment

Figure 0-13: Hardware wiring for Load Encroachment testing


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Load Encroachment function are given in the common section at the beginning of this document.

One relay inputs have to be programmed as a normally open (52a) breaker status monitoring input.

One relay output should be programmed to trip.

IA

IB

IC

IA

IB

IC

ININ

VA VA

VBVB

VC VC

DigitalInputs

RelayOutputs

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs


In 1 Trip

VN VN

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OMICRON LogicPro

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BREAKER FAILURE PROTECTION

ObjectiveThe objective is to perform dynamic test to evaluate the Breaker-Failure-Protection (BFP) function of a distance relay, as a function of the type of fault and the operation of the breaker.

The Test Object is a multifunctional distance relay with built-in Breaker-Failure-Protection at one end of the line.

BFP logic description(BFP - Breaker Failure Protection)

One of the most severe fault conditions in an electric power system is the failure of the breaker to trip in case of a fault detected by the protective relays. This results in prolonged exposure of the system to low voltages and of electrical equipment to large short circuit currents and may lead to a total system collapse. This is the reason that Breaker Failure Protection has gained popularity especially at the transmission level of the system.

Modern microprocessor based transmission protection relays have built-in Breaker Failure Protection functions that vary with the level of complexity between the different relay manufacturers.

The most common Breaker Failure Protection is based on monitoring of the current in the protected circuit. After a fault is detected and the relay issues a trip signal, it will also initiate the timer of the Breaker Failure Protection function. If the breaker trips as expected, the current in all three phases will go to zero, which will reset the undercurrent element used to detect the correct breaker operation.

The above described breaker failure logic works for most cases, especially when the fault condition is a short circuit. However, there are system conditions when the current detector can not be used to detect the breaker trip.

If the transmission line protection is installed on a long line that becomes lightly loaded, this may result in an overvoltage condition that might be dangerous to system equipment. The overvoltage protection will issue a trip signal, but if the breaker fails to trip, it is not going to be detected by the undercurrent element, since the low current was the cause for the high voltage in the first place. A different criteria is required to detect the breaker operation. An auxiliary contact from the breaker can be used for this purpose.

The Breaker Failure Protection function is usually started by a built-in protection function in the transmission line protection relay. However, it can also be used when the decision to trip the same breaker has been made by another protective relay. In this case an external signal will operate an input of the transmission line protection that will initiate the Breaker Failure Protection.


A simplified logic diagram of the (BFP) Breaker Failure Protection function is shown on ( Figure 0-14, page -89 ).

Figure 0-14: Simplified Breaker Failure Protection logic diagram

Fault locationsFaults are simulated at 3 locations along the model transmission line:

1. Zone 1 single-phase-to-ground fault at 50% of the line length


3. Reverse fault


BF Trip

Ia

Ib

Ic


Prot Trip

Ext BF Start

TBF

BF Trip

IUC52

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Figure 0-15: Fault location for the testing of the Breaker Failure Protection logic

Test CasesThe Breaker-Failure-Protection is tested for the following fault conditions:

1. For Zone 1 single-phase-to-ground fault: - the relay should trip with Zone 1 time and should initiate Breaker Failure Protection (but should not trip).

2. For Zone 2 single-phase-to-ground fault and Breaker Failure: - the relay should trip with Zone 2 time and should also trip with Breaker Failure time.

3. For Reverse fault with External Breaker Failure Start: - the relay should trip with Breaker Failure time.

4. For Over-voltage condition and Breaker Failure: - the relay should trip with Over-voltage Protection time and should also trip with Breaker Failure time.


A typical wiring diagram for the Breaker Failure Protection logic test is shown in ( Figure 0-16, page -91 ).

The two potential free relay outputs of the CMC have one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of each relay input is connected to (-) DC.

The Trip output of the relay and the Breaker Failure Trip output are wired to two of the sense inputs of the CMC and are used to change from fault to post-fault state, as well as to measure the operating time and evaluate the correct operation of the Breaker Failure Protection logic during the test.


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA250% 100%


Figure 0-16: Hardware wiring diagram for testing of the Breaker Failure Protection logic


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Breaker Failure Protection logic are given in the common section at the beginning of this document.

The only settings that have to be changed for this group of test cases is the enabling of the Breaker Failure Protection logic and the associated with it relay settings based on the recommendations in the relay service manual.

One relay input has to be programmed as normally open (52a) breaker status monitoring input. A second relay input is designated for external Breaker failure status.

IA

IB

IC

IA

IB

IC

ININ

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs+ DC - DC

+ DC - DC

Out 1

Out 2

52a

Start BF

DigitalInputs

RelayOutputs

In 1 Trip

In 5 BF Trip

VN VN

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One relay output should be programmed to provide Trip, while a second output should give the indication for detected Breaker Failure Protection trip.

Block Reclosing

BLOCK RECLOSING

ObjectiveThe objective is to perform dynamic test to evaluate the Block Reclosing function of a distance relay, as a function of the type of fault, and the breaker status.

The Test Object is a multifunctional distance relay with built-in Block Reclosing at one end of the line.

BR logic description(BR - Block Reclosing)

Most faults on overhead transmission lines are caused by lightning, clashing conductors and other transient phenomena. Electric power stability and reduction of outages can be achieved through automatic reclosing of faulted transmission lines. The success rate of auto reclosing is in the range of 80-90%. After the initial trip, the relay recloses the circuit breaker after a set time delay in order to allow the de-ionization of the air in the fault location.

The remaining percentage of faults is permanent in nature and requires immediate tripping of the line breakers and blocking of the reclosing function. There are different criteria or events that can be used to determine the need to block reclosing:

If the fault detected by the relay is multiphase with high currents, there is higher probability that it is a permanent fault. At the same time exposing the electric power system to such conditions repeatedly during the reclosing sequence can be dangerous for the stability of the system.

If the relay clears a fault with one of it's backup zones - Zone 2 or Zone 3 - there is a possibility that there is some problem with the protection or the breaker at the remote substation that requires block of reclosing.

If the breaker controlled by the transmission line protection relay is not capable of reclosing because of low pressure, or something else, obviously the reclosing should be blocked. This condition is typically detected through a relay input assigned to detect any external Block Reclosing command.

Usually a Switch-Onto-Fault condition is a result of ground-switches not being opened before closing the line breaker after maintenance. This condition is detected based on the monitored by the relay breaker status and with result in reclosing block. A Block Reclose input is typically assigned and will block autoreclose and cause a lockout if autoreclose is in progress. If a single pole cycle is in progress a three pole trip and lockout will result.

It can be used when protection operation without autoreclose is required. A typical example is on a transformer feeder, where autoreclosing may be initiated from the feeder protection but blocked from the transformer protection. Similarly, where a

99

OMICRON LogicPro

100

circuit breaker low gas pressure or loss of vacuum alarm occurring anywhere during the dead time must block autoreclosure, this input can be used.

Choice of Protection Elements to Initiate Autoreclosure

In most applications, there will be a requirement to reclose for certain types of faults but not for others. The logic is partly fixed so that autoreclosure is always blocked for any Switch on to Fault, Stub Bus Protection, Broken Conductor or Zone 4 trip.

Simplified logic for the Block reclosing scheme is shown in ( Figure 0-17, page -94 ).

Figure 0-17: Simplified Block Reclosing logic diagram


1. Internal Zone 1 single-phase-to-ground fault

2. External Zone 2 single-phase-to-ground fault (on the outside of one of the breakers)

3. Switch-Onto-Fault (three phase fault)

Ia

Ib

Ic


Zone 1

SOTF

Multi Phase Flt(3 Phase)

Block Reclosing

Back Up Trip(Zone 3)

Block Reclosing

Figure 0-18: Fault locations for the testing of Block Reclosing logic


Test Cases The Block Reclosing function is tested for the following fault conditions:

1. For Zone 1 single-phase-to-phase fault: - the relay should trip with Zone 1 time and should Block Reclosing.

2. For External single-phase-to-ground Zone3 fault: - the relay should trip with Zone 3 time and should Block Reclosing.

3. For Switch-Onto-Fault (3 Phase): - the relay should trip with Zone 1 time and should Block Reclosing.


A typical wiring diagram for the Block Reclosing logic test is shown in ( Figure 0-19, page -96 ).

The CMC simulates the status of the normally open auxiliary contacts of the breaker, and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.


The Trip output of the relay is wired to the Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA2

50% 100%100%Ext

101

OMICRON LogicPro

102

and together with the monitored Block Reclosing output evaluate the correct phase selection and operation of the Block Reclosing logic during the different fault tests.

Figure 0-19: Hardware wiring for testing of the Block Reclosing logic


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Block Reclosing logic are given in the common section at the beginning of this document.

The only settings that have to be changed for this group of test cases is the enabling of the Reclosing logic, The Block Reclosing function and associated with it settings. Zone2 should be set to Block Reclosing. Different relays may have different protection functions used to make the decision to Block Reclosing. They have to be checked in order to determine which test to run for the evaluation.

IA

IB

IC

IA

IB

IC

I NIN

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs+ DC - DC

+ DC - DC

Out 1

Out 3

52a

Block Reclosing

DigitalInputs

RelayOutputs

In 1 Trip

In 10 Reclose Blocked

VN VN

Block Reclosing


One relay output is programmed as Trip, while a second one is set to indicate the operation of the Block Reclosing logic

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POWER-SWING-BLOCKING

ObjectiveThe objective is to perform dynamic test to evaluate the Power-Swing-Blocking feature of a distance relay, as a function of the system conditions, presence of a fault, and selected mode of operation.

The Test Object is a multifunctional distance relay with Power-Swing-Blocking option available at one end of the line.

Breaker Status signals are simulated by the CMC.

PSB logic description(PSB - Power-Swing-Blocking)

Distance relays are exposed not only to fault, but to other abnormal power system conditions. Power swings are one of the most typical cases that affects distance relays performance because of the specific operating principles. They are oscillations in power flow which can follow a power system disturbance. They can be caused by different fault conditions followed by switching of breakers, sequential operation of protective relays or schemes, loss of synchronism across a power system, or changes in direction of power flow as a result of switching. Such disturbances can cause generators in different parts of the system to accelerate or decelerate in order to adapt to new power flow conditions, which in turn leads to a power swing.

The result of a power swing may cause the apparent impedance seen by the distance relay to move away from the normal load area and into one or more of its tripping characteristics. Since power swing is relatively slow compared to a short circuit fault condition, the power swing impedance can stay in a tripping zone long enough, that will result in a relay trip.

Considering that the power swing was triggered by abnormal system conditions in the first place, any further unnecessary tripping of transmission lines will result in further degradation of the power system conditions and may lead to a system blackout.

Modern distance relays are equipped with functions that detect power swing conditions and block a selected number of distance elements that may operate during a power swing condition.

The most common principle for detection of a power swing condition is the time for passing of the apparent impedance measured by the relay through a power swing impedance band.

A very important characteristic of this process is the fact that power swing is a balanced three phase condition. A power swing is detected when the

Power-Swing-Blocking

phase-to-phase measured impedance has remained within the band in excess of a pre-defined time.

One of the most important criteria for the evaluation of the operation of power swing blocking schemes is their performance when a fault occurs during a power swing. In this case the relay logic should detect the fault condition and issue a correct trip signal.

The power swing characteristic of typical distance relays are shown on ( Figure 0-20, page -99 ) and ( Figure 0-21, page -99 ).

Figure 0-20: Power Swing band for a distance relay with quadrilateral characteristic

Figure 0-21: Power Swing band for a distance relay with mho characteristic

Unblocking of the relay for faults during power swings should allow the relay to operate normally for any unbalanced fault occurring during a power swing, as there are two conditions which can be used to unblock the relay:

PwrSwg ΔR

PwrSwg ΔX

Rch

PwrSwg Δ

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A residual current threshold is exceeded - this allows tripping for ground faults occurring during a power swing.

A negative sequence current threshold is exceeded - this allows tripping for phase-to-phase faults occurring during a power swing.

Simplified logic diagram of the Power Swing Block is shown in ( Figure 0-22, page -100 ).

Figure 0-22: Power Swing Blocking simplified logic diagram

Fault locationsA Zone1 single-phase-to-ground fault is applied following the initial power swing condition.

Test CasesThe Power Swing Blocking scheme is tested for the following system and fault conditions:

1. For power swing inside and out of Zone 3: the relay should not trip and should give Power Swing Alarm

2. For power swing inside of Zone 3 followed by a Zone 1 single-phase-to-ground fault: the relay should trip and should give Power Swing Alarm

Ia

Ib

Ic


Trip

PS Block(enabled)

Fault Detected

BlockZ2tBlockZs

Zpsb Tpsb

Power-Swing-Blocking


A typical wiring diagram for the Power Swing Blocking logic test is shown in:

( Figure 0-23, page -101 ).

The CMC simulates the status of the normally open auxiliary contacts of the breaker, and the currents and voltages during the pre-fault, power swing, fault and post-fault stages of the simulation.


The Trip output of the relay is wired to the Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and together with the monitored Power Swing output evaluate the correct operation of the Power Swing Blocking logic during the different tests.

Figure 0-23: Hardware wiring diagram for testing of the Power Swing Blocking logic

IA

IB

IC

IA

IB

IC

ININ

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs


DigitalInputs

RelayOutputsIn 1 Trip

In 4 Power Swing

VN VN

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Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Power Swing Blocking logic are given in the common section at the beginning of this document.

The only setting that has to be changed for this group of test cases is the enabling of Power Swing Blocking logic. Different relays may have different protection functions used to make the decision to trip.


One relay output is programmed as Trip, while a second one is set to indicate the operation of the Power Swing Blocking logic

The Power Swing band setting expected by the software is 1 ohm.

Power-Swing-Tripping

POWER-SWING-TRIPPING

ObjectiveThe objective is to perform dynamic test to evaluate the Power-Swing-Tripping feature of a distance relay, as a function of the system conditions, presence of a fault, and selected mode of operation.

The Test Object is a multifunctional distance relay with Power-Swing-Tripping option available at one end of the line.

Breaker Status signals are simulated by the CMC.

PST logic description(PST - Power-Swing-Trip)

The Power Swing Tripping logic is based on power swing detection identical to the one used for power swing blocking. However, under certain conditions and depending on the location of the relays in the power system, it might be necessary to separate the two parts of the system when a power swing condition is detected. This is the case of Power Swing Tripping.

Simplified logic for the Power Swing Tripping scheme is shown in ( Figure 0-24, page -103 ).

Figure 0-24: Simplified logic diagram for Power Swing Trip scheme

Ia

Ib

Ic

Trip

PS Trip(enabled)

TripZs

Zps Tps

Z3

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Fault locationsThere are no faults applied in the tests for Power Swing Tripping.

Test CasesThe Power Swing Tripping scheme is tested for the following system and fault conditions:

1. For power swing inside and out of Zone 3: the relay should not trip and should give Power Swing Alarm

2. For power swing inside of Zone 3: the relay should trip and should give Power Swing Alarm

Hardware Requirements

Figure 0-25: Hardware wiring for testing of the Power Swing Tripping logic

The CMC test device is programmed to simulate the substation and power system environment through the analog and binary inputs. At the same time the binary inputs are used to monitor the operation of the test object.

IA

IB

IC

IA

IB

IC

ININ

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs


DigitalInputs


In 4 Power Swing

VN VN

Power-Swing-Tripping

A typical wiring diagram for the Power Swing tripping logic test is shown in ( Fig. 0-25, page - 104).

The CMC simulates the status of the normally open auxiliary contacts of the breaker, and the currents and voltages during the pre-fault, power swing, fault and post-fault stages of the simulation.


The Trip output of the relay is wired to the Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and together with the monitored Power Swing output evaluate the correct operation of the Power Swing Tripping logic during the different tests.


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Power Swing Tripping logic are given in the common section at the beginning of this document.

The only setting that has to be changed for this group of test cases is the enabling of Power Swing Tripping logic. Different relays may have different protection functions used to make the decision to trip.


One relay output is programmed as Trip, while a second one is set to indicate the operation of the Power Swing Tripping logic

The Power Swing band setting expected by the software is 1 ohm.

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LOSS-OF-POTENTIAL

ObjectiveThe objective is to perform dynamic test to evaluate the Loss-of-Potential (LOP) scheme of a distance relay, as a function of the voltage failure, fault condition or combination of the two.

The Test Object is a multifunctional distance relay with LOP scheme at one end of the line. The single phase or three phase micro-breaker status signals are generated by the CMC.

LOP logic description(LOP - Loss-Of-Potential)

The circuits between the voltage transformers in the field and the relays are usually protected by fuses or miniature circuit breakers. In case of a fault on these circuits the fault will be cleared by these protective devices, resulting in the loss of voltage in the faulted phase of the voltage circuit.

Since the distance measured by the relay is a function of the voltage measurement, a zero voltage will result in a distance element seeing a fault inside of the distance characteristic and the relay will trip even with a small load current.

Such maloperation is undesirable and requires taking some measures in order to avoid it. Any modern microprocessor based distance relay includes some form of logic that will detect such condition and prevent the relay operation. These schemes can have different names in different products, but the functionality is very similar. In some relays this is the Fuse-Failure scheme, while in others it may be a Loss-of-Potential scheme. Or it may be called a Voltage-Transformer-Supervision scheme. However, in all cases the logic is based on the detection of a change in voltage while there is no change in current.

Modern microprocessor based relays measure typically phase currents and voltages and based on these measurements calculate the sequence components used by different protection or non-protection functions. When a single or two phase voltage failure occurs, this will result in voltage unbalance that can be detected based on the calculated negative or zero sequence voltages.

The detection of unbalance voltage however should not affect the performance of the relay under fault conditions. That is why the Loss-of-Potential logic includes another element that monitors the availability of unbalanced current conditions. Under normal load conditions, the current unbalance will be a function of the loading of the line and the line transposition. For untransposed circuits the difference between the currents in the individual phases can go up to 7-10%. The setting of the element detecting unbalanced current conditions should be set above this possible level in order to ensure the correct logic operation.

Loss-Of-Potential

Detection of Loss-of-Potential should immediately block all voltage dependent elements, such as distance and directional functions. At the same time pure overcurrent elements should be available to provide some form of backup protection in the case that a fault occurs before the problem with the voltage circuits or transformers is detected and fixed.

The above requirements are taken into consideration in the design of the module for testing of the Loss-of-Potential logic in modern transmission line protection relays.

A simplified diagram of the Loss-of-Potential logic is displayed on ( Figure 0-26, page -107 )

Figure 0-26: Simplified Loss-of-Potential logic diagram



The fault location is shown on ( Figure 0-27, page -108 )

0

0

0

Substation A

(disabled)

V0 or V2

I0 or I2

Distance

Direction

IOC

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Figure 0-27: Fault location for the testing of the Loss-of-Potential logic

Test CasesThe Loss-of-Potential (LOP) scheme is tested for the following fault conditions:

1. For Single-phase voltage failure: - the relay should not trip and should give a LOP alarm.

2. For Single-phase-to-ground Zone 1 fault: - the relay should trip and should not give a LOP alarm.

3. For Single-phase voltage failure followed by Single-phase-to-ground Zone 1 fault: - the relay should give a LOP alarm and then trip.


A typical wiring diagram for the Loss-of-Potential logic test is shown on ( Figure 0-28, page -109 ).

The CMC simulates the status of the normally open auxiliary contact for the breaker (52-A), the status of the micro-breaker in the voltage circuit (if required by the relay logic) and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA250%

Loss-Of-Potential

Figure 0-28: Hardware wiring diagram for testing of the Loss-of Potential logic

The two potential free relay outputs of the CMC have one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of each relay input is connected to (-) DC.

The Trip output of the relay is wired to a Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and evaluate the correct operation of the Loss-of-Potential logic during the test.


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Loss-of-Potential logic are given in the common section at the beginning of this document.

IA

IB

IC

IA

IB

IC

I NIN

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs

+ DC - DC

+ DC - DC

Out 1

Out 2

52a

52bkr

DigitalInputs

RelayOutputs

In 1 Trip

In 6 LOP

VN VN

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OMICRON LogicPro

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The only setting that has to be changed for this group of test cases is the enabling of the Loss-of-Potential logic and the associated with it relay settings based on the recommendations in the relay service manual.

One relay input has to be programmed as normally open (52a) breaker status monitoring input. A second input should be configured to monitor the status of a Micro-breaker used to protect the voltage circuit.

One relay output should be programmed to provide Distance Trip while a second output should give the indication for detected Loss-of-Potential.


CURRENT TRANSFORMER SUPERVISION

ObjectiveThe objective is to perform dynamic test to evaluate the Current-Transformer Supervision scheme of a distance relay, as a function of the Current Transformer or other CT failure or fault condition, or combination of the two.

The Test Object is a multifunctional distance relay with Current Transformer Supervision scheme at one end of the line.

CTS logic description(CT - Current-Transformer Supervision)

The current circuits of a transmission line protection relay may fail due to gradual degradation of the current transformers themselves or damage of the wiring between the current transformers in the field and the relays. In some cases this may lead to incorrect measurement of the primary load or fault currents and incorrect operation of the protective relay. A dangerous raise in voltage will result from an interruption of the current circuit. All this requires detection and alarm from the relay when such problems occur in the substation.

Some modern microprocessor based distance relays includes some form of logic that will detect such CT circuit condition and prevent the affected relay functions from incorrect operation. These schemes may be called a Current-Transformer-Supervision scheme. The logic follows similar principles to the Voltage-Transformer-Supervision logic, but with reversed signals, i.e. it is based on the detection of a change in current while there is no change in voltage.

Modern microprocessor based relays measure typically phase currents and voltages and based on these measurements calculate the sequence components used by different protection or non-protection functions. When a single or two phase current failure occurs, this will result in current unbalance that can be detected based on the calculated negative or zero sequence currents.

The detection of unbalance currents however should not affect the performance of the relay under fault conditions. That is why the Current-Transformer-Supervision logic includes another element that monitors the availability of unbalanced voltage conditions. Under normal load conditions, the current unbalance will be a function of the loading of the line and the line transposition. For untransposed circuits the difference between the currents in the individual phases can go up to 7-10%. The setting of the element detecting unbalanced current conditions should be set above this possible level in order to ensure the correct logic operation.

Detection of Current-Transformer-Supervision should block sequence current dependent elements, such as sensitive negative or zero sequence overcurrent functions. At the same time pure phase high set overcurrent elements should be

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available to provide some form of backup protection in the case that a fault occurs before the problem with the current circuits or transformers is detected and fixed.

The above requirements are taken into consideration in the design of the module for testing of the Current-Transformer-Supervision logic in modern transmission line protection relays.

Simplified diagram of the Current-Transformer-Supervision logic is shown in:

( Figure 0-29, page -112 ).

Figure 0-29: Simplified Current-Transformer Supervision logic diagram



The fault location is shown on ( Figure 0-30, page -113 )

Ia

Ib

Ic

Substation A

V0 or V2

I0 or I2

Distance

Negative Seq. OC

Ground OC


Figure 0-30: Fault location for the testing of the Current-Transformer Supervision logic

Test CasesThe Current Transformer Supervision scheme is tested for the following fault conditions:

1. For Single-phase CT circuit failure: - the relay should not trip and should give a CT alarm.

2. For Single-phase-to-ground Zone1 fault: - the relay should trip and should not give a CT alarm.

3. For Single-phase CT circuit failure followed by Single-phase-to-ground Zone1 fault: - the relay should give a CT failure alarm and then trip with distance element.


A typical wiring diagram for the Current-Transformer Supervision logic test is shown in ( Figure 0-31, page -114 )

The CMC simulates the status of the normally open auxiliary contact for the breaker (52-A), and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA250%

119

OMICRON LogicPro

120

Figure 0-31: Hardware wiring diagram for testing of the Current-Transformer- Supervision logic


The Trip output of the relay is wired to a Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and evaluate the correct operation of the Current-Transformer Supervision logic during the test.

A second output from the relay is wired to input 2 in order to provide indication of the detection of CT Failure.


IA

IB

IC

IA

IB

IC

ININ

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs


DigitalInputs


In 7 CT Fail

VN VN


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Current-Transformer Supervision logic are given in the common section at the beginning of this document.

The only setting that has to be changed for this group of test cases is the enabling of the Current-Transformer Supervision logic and the associated with it relay settings based on the recommendations in the relay service manual.

One relay input has to be programmed as normally open (52a) breaker status monitoring input.

One relay output should be programmed to provide Trip, while a second output should give the indication for detected Current-Transformer Supervision.

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STUB BUS PROTECTION

ObjectiveThe objective is to perform dynamic tests to evaluate the Stub-Bus-Protection feature of a distance relay, as a function of the fault location, type of fault, and selected mode of operation.

The Test Object is a multifunctional distance relay with a Stub-Bus-Protection option available at one end of the line.

The breaker and line switch status signals are generated by the CMC.

STP logic description(STP - Stub-Bus-Protection)

Where a transmission line is connected to a substation with a ring-bus or breaker -and-a-half configuration, the relay is typically connected to two circuit breakers and there is a line switch that allows taking the line out-of-service while the ring or the breaker-and-a-half bay remains in service.

There are two typical arrangements, the more common being paralleling the two sets of current transformers (one from each breaker). An alternative is two have two sets of current inputs in the transmission line protection relay.

When the line is opened, in the case of any load or through fault condition, the relay will see the difference between the currents flowing through the two breakers. This should result in zero current being seen from the protective relay. However, this is valid only when the two sets of line Acts should be well matched and equally loaded, such that the relaying connection is at the equipotential point of the secondary leads.

For any fault between the breakers and the line switch the relay will see the sum of the fault currents through the breakers and will issue a trip signal to operate the two breakers.

Many transmission line protection relays include a function that provides the so called stub bus protection - i.e., protection of the part of the substation bus between the two breakers and the line switch. The state of the line - in or out of service - is determined based on monitoring the state of the line switch through one of it's auxiliary contacts. When it is open, an auxiliary contact can be used to energize an input on the relay to enable this protection function.

For an internal fault the relay will operate, tripping the two local circuit breakers.

The above requirements are taken into consideration in the design of the module for testing of the Stub Bus Protection logic in modern transmission line protection relays external and internal fault conditions.

Stub Bus Protection

Simplified diagram of the Stub Bus Protection logic, that should be enabled when testing the relay under evolving fault conditions is shown in ( Figure 0-32, page -117 ).

Figure 0-32: Simplified Stub-Bus-Protection logic diagram

Fault locationsFaults are simulated at two locations on the substation bus:

1. Internal single-phase-to-ground fault (between the breakers and the line switch)

2. External single-phase-to-ground fault (on the outside of one of the breakers)

Substation A

CT

Trip

Line Switch (LS)

Instant OC

LS Open

CT

CT

CT

CT

CT

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OMICRON LogicPro

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Figure 0-33: Fault locations for the testing of the Stub-Bus-Protection logic


Test CasesThe Stub-Bus-Protection scheme is tested for the following fault conditions:

1. For Single-phase-to-ground fault inside the zone of protection: - the relay should trip without time delay.

2. For Single-phase-to-ground fault outside the zone of protection: - the relay should not trip.


A typical wiring diagram for the Stub Bus Protection logic test is shown in ( Figure 0-34, page -119 )

The CMC simulates the status of the normally open auxiliary contacts of the breakers, the state of the line switch and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.

Substation A

CTLine Switch (LS)

Relay

CT

CT

CT

CT

CT

Stub Bus Protection

All three potential free relay outputs of the CMC have one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of each relay input is connected to (-) DC.

The Trip output of the relay is wired to the Trip sense input of the CMC and is used to change from fault to post-fault state, as well as to measure the operating time and evaluate the correct operation of the Stub Bus Protection logic during the different fault tests.

A Stub Bus Protection output from the relay is wired to output 2.

Figure 0-34: Hardware wiring diagram for testing of the Stub-Bus-Protection logic


Test object settingsThe expected basic settings of the multifunctional relay under test associated with the Stub-Bus Protection logic are given in the common section at the beginning of this document.

IA

IB

IC

IA

IB

IC

I NIN

VA VA

VBVB

VC VC

CM C RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs

+ DC - DC

- DC

+ DC - DC

Out 1

Out 4

52a1

52a2

Line Switch

DigitalInputs


VN VN

In 8 Stub Bus

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OMICRON LogicPro

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The only setting that has to be changed for this group of test cases is the enabling of Stub-Bus Protection logic. Different relays may have different protection functions used to make the decision to trip.

One relay input has to be programmed as a normally open (52a) breaker status monitoring input for Breaker 1.

A second relay input has to be programmed as a normally open (52a) breaker status monitoring input for Breaker 2.

A third relay input should be programmed as a normally closed (52b) line switch position monitoring input.

One relay output should be programmed to Trip phase and a second relay output should provide indication of the operation of the Stub-Bus Protection logic.


SINGLE POLE TRIPPING

ObjectiveThe objective is to perform dynamic tests to evaluate the performance of a distance relay, as a function of the fault location, type of fault, and selected mode of operation for different fault conditions.

The Test Object is a multifunctional distance relay with Single-Pole-Tripping option available and enabled. The performance of the relay at one end of the line is tested. Breaker status and 3 Pole Trip Only signals are simulated by the CMC.

SPT logic description(SPT - Single-Pole-Tripping)

Transmission lines are very important to the overall stability of the power system during different abnormal power system conditions. Any loss of lines can significantly affect the system when a short circuit fault occurs and may lead to a sequence of events that may result in a total system collapse.

Protection and system engineers have established different practices in order to improve the system performance under such conditions. Since many faults are temporary in nature, automatic reclosing is the preferred method for restoring the system configuration to pre-fault conditions. However, during the reclosing cycle the line will be out of service, which combined with the effect of the voltage drop during the process of fault detection and clearing may result in system instability. Considering the fact that most of the faults in the system, (especially at the high and extremely high voltage levels are single-phase to ground faults), one solution is to implement single-pole tripping and reclosing. This will allow continuous power transfer through the healthy phases during the reclosing cycle and will significantly improve the stability of the system.

The decision to implement single pole tripping should be made after consideration of several different factors, such as the availability of secondary arc current due to electromagnetic or electrostatic coupling between the healthy phases and the tripped phase, as well as the expected de-ionization time.

Modern transmission line protection relays are designed to allow single pole tripping as a function of the detected fault conditions and the type of reclosing applied. They also implement logic that is trying to distinguish between temporary and permanent faults in order to avoid reclosing into a fault. On the other hand, the severity of the fault will affect the stability of the system, so it is taken under consideration by the relay logic is well. The decision of what behavior the relay should have is specified by the protection engineer during the setting of the relay.

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Figure 0-35: Simplified Single Pole Tripping logic diagram

The most typical cases when single pole trip and reclosing is selected is to trip single phase for single-phase to ground faults and trip three phase for any other fault. Also to trip single-phase for faults in Zone 1 of the protected line and three phase for any other Zone. The latter is due to the fact, that Zone 2 and Zone 3 provide backup protection, and in this case a three phase trip is required.

Under specific conditions the application may require the relay to convert a single pole trip decision to a three phase trip. This is typically based on the status of an opto input that if energized will force the relay to trip three phase even when it has detected a single-phase to ground fault.

The above requirements are taken into consideration in the design of the module for testing of the Single-Pole Trip and Reclosing logic in modern transmission line protection relays.

Simplified diagram of the Single-Pole Tripping logic is shown in ( Figure 0-35, page -122 ).

0

0

0


Trip AZ1 A

Z1 B

Z1 C

Trip B

Trip CTrip 3 Ph

Z1 CA

Z1 ABC

3Ph Only

Z1 ABZ1 BC


Fault locations

Figure 0-36: Fault locations for the testing of the Single-Pole Tripping logic

Faults are simulated at 2 locations along the model transmission line:


2. Zone 1 three-phase-to-ground fault at 50% of the line length

The three fault locations are shown on ( Figure 0-36, page -123 ).

Test cases

The Single Pole Tripping scheme is tested for the following fault conditions:

1. For Zone1 single-phase-to-ground fault: - the relay should trip single pole with Zone1 time.

2. For Zone1 phase-to-phase fault: - the relay should trip 3 pole with Zone1 time.

3. For Zone1 single-phase-to-ground fault with 3 Pole Trip Only energized: - the relay should trip 3 pole with Zone1 time.


The CMC test device is programmed to simulate the substation and power system environment through the analog and binary inputs. At the same time the binary inputs are used to monitor the operation of the test object.

A typical wiring diagram for the Single-Pole Tripping logic test is shown in ( Figure 0-37, page -124 )

The CMC simulates the status of the normally open auxiliary contacts for the three phases of the breaker (52a-A, 52a-B and 52a-C) and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA2

50%

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Note: If the relay uses a 52b breaker status contact, it should not be wired.

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Another potential free relay output of the CMC is programmed to simulate the 3 Phase Trip Only signal sent from an external relay or another control signal and is wired to the appropriate input of the relay under test.

All four potential free relay outputs of the CMC have one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of each relay input is connected to (-) DC.

Figure 0-37: Hardware wiring diagram for testing of the Single-Pole Tripping logic

The three Trip outputs of the relay (one for each phase) are wired to three Trip sense inputs of the CMC and are used to change from fault to post-fault state, as well as to measure the operating time and evaluate the correct phase selection and operation of the Single-Pole Trip logic.

A 3 Phase Trip output of the relay is wired to a fourth sense input of the CMC and is used as an additional criteria from the relay under test.

IA

IB

IC

IA

IB

IC

I NIN

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs

+ DC - DC

+ DC - DC

Out 1

Out 2

52aA

52aB

+ DC - DCOut 3 52aC

DigitalInputs

RelayOutputs

In 2

In 1 Trip A

Trip B

In 3 Trip C

VN VN

+ DC - DCOut 4 3Ph Trip Only


Automatic test sequence

The automatic test sequence will have several steps shown with animation in the LogicPro software. Only the steps related to the relay at the local end are executed.

Test object settings

The expected basic settings of the multifunctional relay under test associated with the Single-Pole Trip logic are given in the common section at the beginning of this document.

The only setting that has to be changed for this group of test cases is the enabling of Single Pole Trip.

Three relay inputs have to be programmed as single phase normally open (52a) breaker status monitoring inputs. Another input should be configured to convert any trip to three phase trip.

Three relay outputs should be programmed to trip phase A, B and C accordingly, while at the same time a fourth output should indicate a relay three phase trip.

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EVOLVING FAULT LOGIC

Objective

The objective is to perform dynamic tests to evaluate the performance of a distance relay, as a function of the fault location, type of fault, and selected mode of operation for different fault conditions.

The Test Object is a multifunctional distance relay with Single-Pole-Tripping option available and enabled. The performance of the relay at one end of the line is tested.

Breaker status signals are simulated by the CMC.

Evolving Fault logic description

(EF - Evolving Fault)

The advantages and importance of single pole trip and reclosing were discussed in the previous section discussing the testing of this feature in transmission line protection relays. The fault conditions in the system can change dynamically during the process of fault detection and fault clearance.

Distance relays typically include several different elements that operate in parallel or in sequence depending on the design and/or algorithms implemented in the relay under test. One of them is the faulted phase selection function that identifies the type of fault and enables a phase-to-ground or a phase-to-phase distance element to make a decision to trip. However, it is possible that after the relay has made this decision to trip single pole for a single-phase-to-ground fault, the fault may evolve to a phase-to-phase or three-phase fault before the breaker has tripped.

A properly designed relay should be able to detect the changing fault conditions and switch from a single pole trip to a three phase trip decision. Obviously, if three phase trip mode is selected, even if the single-phase-to-ground fault evolves to a multi-phase fault before the breaker trip, all three phases will be tripped, so the fault will be cleared correctly. The only concern will be the fault record from the relay, that may provide misleading information about the type of fault detected by the relay.

The above requirements are taken into consideration in the design of the module for testing of the Single-Pole Trip and Reclosing logic in modern transmission line protection relays for normal and evolving fault conditions.

A simplified diagram of the Single-Pole Tripping logic that should be enabled when testing the relay under evolving fault conditions is shown on ( Figure 0-38, page -127 ).

Evolving Fault Logic

Figure 0-38: Simplified diagram for testing of the Evolving Fault logic

Fault locations

Faults are simulated at one location along the model transmission line:


2. Zone 1 single-phase-to-ground fault evolving to three-phase-to-ground fault at 50% of the line length

The fault location is shown on ( Figure 0-39, page -127 ).

Figure 0-39: Fault location for the testing of the Evolving Fault function of Single-Pole Tripping logic

0

0

0


Trip AZ1 A

Z1 B

Z1 C

Trip B

Trip CTrip 3 Ph

Z1 CA

Z1 ABC

3Ph Only

Z1 AB

Z1 BC


VBRVAR

VCR

IBr

ICr

IAr

Relay

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VA2

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Test cases

The distance relay is tested for the following fault conditions:

1. For Zone1 single-phase-to-ground fault: - the relay should trip single pole with Zone1 time.

2. For Zone1 single-phase-to-ground fault evolving to three-phase-to-ground fault: - the relay should trip first single-pole with Zone1 time and then trip 3 pole.


The CMC test device is programmed to simulate the substation and power system environment through the analog and binary outputs. At the same time the binary inputs are used to monitor the operation of the test object.

A typical wiring diagram for the Single-Pole Tripping logic test is shown in ( Figure 0-40, page -129 )

The CMC simulates the status of the normally open auxiliary contacts for the three phases of the breaker (52a-A, 52a-B and 52a-C) and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.

All four potential free relay outputs of the CMC have one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of each relay input is connected to (-) DC.

The three Trip outputs of the relay (one for each phase) are wired to three Trip sense inputs of the CMC and are used to change from fault to post-fault state, as well as to measure the operating time and evaluate the correct phase selection and operation of the Single-Pole Trip logic during the evolving fault test.

Evolving Fault Logic

Figure 0-40: Hardware wiring diagram for testing of the Evolving Fault logic

Automatic test sequence

The automatic test sequence will have several steps shown with animation in the LogicPro software. Only the steps related to the relay at the local end are executed.

Test object settings

The expected basic settings of the multifunctional relay under test associated with the Single-Pole Trip logic are given in the common section at the beginning of this document. Trip logic are given in the common section at the beginning of this document.

The only setting that has to be changed for third group of test cases is the enabling of Single-Pole-Trip.


IA

IB

IC

IA

IB

IC

I NIN

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs

+ DC - DC

+ DC - DC

Out 1

Out 2

52aA

52aB

+ DC - DCOut 3 52aC

DigitalInputs

RelayOutputs

In 2

In 1 Trip A

Trip B

In 3 Trip C

VN VN

+ DC - DCOut 4 3Ph Trip Only

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A fourth input of the relay is programmed for 3Phase Trip Only control.

Three relay outputs should be programmed to trip A,B and C accordingly. A fourth output indicates that the relay issued a 3Phase Trip signal.

Pole-Dead Logic

POLE-DEAD LOGIC

ObjectiveThe objective is to perform dynamic tests to evaluate the performance of a distance relay, as a function of the breaker status, fault location, type of fault, and selected mode of operation for different fault conditions.

The Test Object is a multifunctional distance relay with Single-Pole-Tripping option available and enabled. The performance of the relay at one end of the line is tested.

Breaker status signals for each of the three phases of the breaker are simulated by the CMC.

Pole-Dead logic description(PDL - Pole-Dead Logic)

Modern protective relays are designed to operate based on the changing system conditions and status of substation equipment. One of the most important devices related to protection operation is the breaker, or other switching devices. Information on the status of the breaker is used by different logic schemes and is determined by the Pole Dead logic of the protection device.

The Pole Dead detection logic provides individual indication of the status of the circuit breaker poles and indication of any pole dead or all poles dead. The results are later used by different protection and control functions of transmission line protection relays. Pole Dead detection logic typically uses inputs from the circuit breaker normally open (52a) or normally closed (52b) auxiliary contact(s). In some cases for improved reliability of the breaker status detection, both normally open and normally closed auxiliary contacts are monitored.

In case of three pole trip and reclosing a single input to the relay for breaker status is used. When single-pole trip and reclosing is applied, breaker status indication from each individual phase is required.

If breaker auxiliary contact status is not available, the breaker status can be evaluated based on current and voltage measurements.

A pole is detected as dead if either the auxiliary switch input is active or neither the

current nor voltage level detector on that phase is operated.

The pole dead indications are typically used in Switch on to Fault and Trip on Reclose logic. In some cases this information can be used also to detect breaker opening for non-fault trip conditions such as overvoltage protection operation.

A simplified diagram of the Pole-Dead detection logic that should be enabled when testing the relay under evolving fault conditions is shown in ( Figure 0-41, page -132 ).

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Figure 0-41: Simplified Pole-Dead logic diagram



2. Zone 1 three-phase fault at 50% of the line length

Figure 0-42: Fault locations for the testing of the Pole Dead logic

Ia

Ib

Ic

Substation A

Pole Dead A

Ib

Vb

CBb

Pole Dead C

Ic

Vc

CBc

Any Pole Dead

All Pole Dead

Ia

Va

CBa

Pole Dead B


VBRVAR

VCR

IBr

ICr

IAr

Relay

VB2VC2

VA2

50%

Pole-Dead Logic


Test CasesThe Pole-Dead-Logic scheme is tested for the following conditions:

1. Zone 1 single-phase-to-ground fault with Line side VT with single-pole trip: - the relay should trip and detect single pole dead condition.

2. Zone 1 single-phase-to-ground fault with Bus side VT with single-pole trip: - the relay should trip and detect single pole dead condition.

3. Zone 1 three-phase fault with Line side VT with single-pole trip: - the relay should trip and detect three pole dead condition.

4. Zone 1 three-phase fault with Bus side VT with single-pole trip: - the relay should trip and detect three pole dead condition.


A typical wiring diagram for the Pole Dead logic test is shown in ( Figure 0-43, page -134 ).

The CMC simulates the status of the normally open auxiliary contacts for the three phases of the breaker (52a-A, 52a-B and 52a-C) and the currents and voltages during the pre-fault, fault and post-fault stages of the simulation.

All three potential free relay outputs of the CMC have one terminal connected to (+) DC and the second terminal to the (+) DC terminal of the associated relay input. The second terminal of each relay input is connected to (-) DC.

One Trip output of the relay is wired to a Trip sense input of the CMC and are used to change from fault to post-fault state, as well as to measure the operating time and evaluate the operation of the relay. Two other outputs of the relay are designated as Single-Pole-Dead and All Pole Dead indicators and are wired to two other inputs of the CMC. They are used to monitor the correct Pole Dead logic decision during each test.

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Figure 0-43: Hardware wiring diagram for testing of the Pole-Dead logic


Test object settingsThere are no specific settings associated with the Pole Dead logic. Since the more complicated tests are in the case of single-pole trip and reclosing, the only setting that has to be changed for this group of test cases is the enabling of Single Pole Trip.

IA

IB

IC

IA

IB

IC

I NIN

VA VA

VBVB

VC VC

CMC RELAY

AnalogInputs

AnalogOutputs

DigitalOutputs

DigitalInputs

+ DC - DC

+ DC - DC

+ DC - DC

Out 1

Out 2

Out 3

52aA

52aB

52aC

DigitalInputs

RelayOutputs

In 1 Trip

In 6

In 5 Pole-Dead

3 Pole-Dead

VN VN

Pole-Dead Logic


Three relay outputs should be programmed to indicate Trip, Single Pole Dead or All Poles Dead.

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