role of c & i in thermal power plant

Summer Training Project Report“Overview and Role of C & I in Thermal Power Plant”

Submitted by:GAURAV RAIIET, BUNDELKHAND UNIVERSITYJHANSI (UP)

Theme:Power plant C&I (IPC) systems

&Tending to Zero Forced Outage

byInternalization of Best Practices

Presentation Outline:1.Some definitions & basics of Pressure, Flow & Temp. measurement

2. Categorization of C&I systems based on location of application3. Division of power plant C&I systems based on functionality & type of

application

4.Evolution of C&I systems and latest trend in technology

5.Reliance Power at a glance and maintenance practices of C&I systems

6. Some case studies

Measurement: PressureOutline: Some Definitions Pressure Units Manometers Elastic Pressure Sensors Electrical Pressure Sensors Pressure Switches Snubbers & Siphon Tubes

Measurement: PressureTerminology

Accuracy : Closeness with which an instrument reading approaches the true value of the variable being measured.

Precision : A measure of reproducibility of the measurements; i.e. given a fixed value of a variable, precision is a measure of the degree which successive measurements differ from one another.

Sensitivity : The ratio of output signal or response of the instrument to a change of input or measured variable.

Resolution : The smallest change in measured value to which the instrument will respond.

Error : Deviation from the true value of the measured variable.

Measurement: PressureRepeatability refers to the ability of a pressure sensor to provide the same output with successive applications of the same pressure.Hysteresis is a sensor's ability to give the same output at a given pressure while increasing and decreasing the pressure.

Measurement: PressurePressure : Definitions

Definition: Force per unit area Absolute pressure Atmospheric pressure Differential pressure Gauge pressureImportance : Pressure measurement is critical for safe and optimum

operation of processes such as steam generation, hydraulic equipment operation, air compression, vacuum processing etc.

Measurement: PressureZero Reference , Gauge, Absolute, Atmospheric

Pressure Any pressure above atmosphere is called gauge pressure Any pressure below atmosphere is a vacuum (negative gauge pressure) Absolute pressure (psia) is measured from a perfect vacuum

Differential Pressure has no reference to either absolute vacuum or atmospheric pressure

Measurement: PressureUnits

The SI unit for pressure is the Pascal (Pa);1Pa= 1 N·m-2

Non-SI unit pound (Lb) per square inch (psi) and bar are commonly used

Pressure is sometimes expressed in grams-force/cm2or as kgf/cm2 (KSC)

1 atm=1.03 ksc=14.696 psi=760mmHg=10000 mmWC =101325 Pa

Standard pressure:Pressure of normal (standard) atmosphere is defined as standard pressure

http://en.wikipedia.org/wiki/SI

http://en.wikipedia.org/wiki/Pascal_(unit)

http://en.wikipedia.org/wiki/Pound-force

http://en.wikipedia.org/wiki/Inch

http://en.wikipedia.org/wiki/Pound-force_per_square_inch

http://en.wikipedia.org/wiki/Bar_(unit)

Measurement: PressurePressure Measuring devices

Manometers using water ,mercury and other liquids of known density For measuring low pressures.

Mechanical/Elastic Pressure Sensors Electrical Pressure Transducers

For measuring pressure of all ranges for telemetering purposes.Manometer:A simple pressure standardMay be used for gauge, differential, and absolute measurements with a suitable reference. Useful mainly for lower pressure work because the height of the column of mercury will otherwise become very high. The difference in column heights gives the pressure reading

Measurement: PressureElastic Pressure Sensors

The basic pressure sensing elements:

A: C-shaped Bourdon tube , B: Helical Bourdon tube , C: flat diaphragm

D: Convoluted diaphragm, E: Capsule , F: Set of bellows

Measurement: PressureElectrical Pressure Sensors

1. Potentiometer Sensor2. Inductive3. Capacitive 4. Piezoelectric5. Strain Gauge

Usually generate output signals in the mV range (spans of 100 mV to 250 mV).

In transmitters, these are amplified to the voltage level (1to 5 V) and converted to current loops, usually 4-20 mA dc

Measurement: PressurePressure Switches

Applications Alarm (Status) Shutdown (Hi/Lo Limits) Control (ON/OFF)

A “switch” is an instrument that automatically senses some process variable (such as pressure) and provides an on/off signal relative to some reference point.

Sensing Element

ConditioningCircuit

Bourdon TubeBellows

DiaphragmStrain Gauge

Mechanical SwitchTransistor

Set Point

Measurement: PressureHigh Pressure In High Temperature

* When high process temperatures are present, various methods of isolating the pressure instrument from the process are used.

* These include siphons, chemical seals with capillary tubing for remote mounting, and purging.

Snubbers & its use Chemical Seal

Siphon

Measurement: PressurePressure Snubbers

To filter out pressure spikes, or to average out pressure pulses, snubbers are installed between the process and the instrument

Instrument indicates avg pr.

Snubber Before use After use when one is interested in the measurement of fast, transient

pressures (such as to initiate safety interlocks on rising pressures), snubbers must not be used, as they delay the response of the safety system.

Measurement: PressureChemical Seal or diaphragm Protector

Chemical seals are used when media can falsify the pressure measurements due to high temperature, high viscosity or their property to crystallise

Measurement: PressureSiphon

A siphon is a coiled tube. This coil provides a large cooling surface and the trap created prevents the condensate from draining away.

A siphon is required for hot condensing. fluids, such as steam, to assure a liquid trap.

It is used to prevent live steam from entering and damaging the device.

It is used to protect the instrument from hydraulic or thermal shocks. The two most common forms of siphon tube are the 'U' and Pigtail

types.

Measurement: FlowTypes of flow meters:1. Orifice Flow meter 2. Vortex flow meter3. Ultrasonics flow meter4. Coriolis Mass Flow meter5. Major issues for selecting flow meters

Orifice Flow-meters Several sensors rely on the pressure drop or head occurring as a fluid flows by a

resistance. The relationship between flow rate and pressure difference is determined

by the Bernoulli equation.

Measurement: FlowOrifice Flow-meters

•An orifice plate is a restriction with an opening smaller than the pipe diameter which is inserted in the pipe; the typical orifice plate has a concentric, sharp edged opening.

• Because of the smaller area the fluid velocity increases, causing a corresponding decrease in pressure.

•The flow rate can be calculated from the measured pressure drop across the orifice plate, P1-P3.

• The orifice plate is the most commonly used flow sensor, but it creates a rather large non-recoverable pressure due to the turbulence around the plate, leading to high energy consumption.

Measurement: FlowVenturi Tube

The change in cross-sectional area in the venturi tube causes a pressure change between the convergent section and the throat, and the flow rate can be determined from this pressure drop. Although more expensive that an orifice plate; the venturi tube introduces substantially lower non-recoverable pressure drops

Measurement: FlowPitot Tubes

Pitot tubes were invented by Henri Pitot in 1732 to measure the flowing velocity of fluids. Basically a differential pressure (dp) flow meter, a pitot tube measures two pressures: the static and the total impact pressure.

Pitot tubes are used to measure air flow in pipes, ducts, stacks, and liquid flow in pipes, open channels.

While accuracy and rangeability are relatively low, pitot tubes

are simple, reliable, inexpensive, and suited for a variety of environmental conditions, including extremely high temperatures and a wide range of pressures.


A single-port pitot tube can measure the flow velocity at only a single point in the cross-section of a flowing stream.

The probe must be inserted to a point in the flowing stream where the flow velocity is the average of the velocities across the cross-section, and its impact port must face directly into the fluid flow.


The point velocity of approach (VP) can be calculated by taking the square root of the difference between the total impact pressure (PT) and the static pressure (P) and multiplying that by the C/D ratio, where C is a dimensional constant and D is density:

The pitot tube measures the static and dynamic (or impact) pressures of the fluid at one point in the pipe.

The flow rate can be determined from the difference between the static and dynamic pressures which is the velocity head of the fluid flow.

Measurement: FlowVortex Flow-meters

This measuring principle is based on the fact that vortices are formed downstream of an obstacle in a fluid flow, e.g. behind a bridge pillar.

This phenomenon is commonly known as the Kármán vortex street.

Measurement: FlowVortex Flow-meters

This is detected by a sensor, such as capacitive sensor and fed to the electronic processor as a primary, digitized, linear signal.

Capacitive sensors with integrated temperature measurement can directly register the mass flow of saturated steam as well.

Universally suitable for measuring liquids, gases and steam Largely unaffected by changes in pressure, temperature

and viscosity High long-term stability (lifetime K factor), no zero-point

drift No moving parts Marginal pressure loss

Measurement: FlowUltrasonic flow-meters

Swimming against the flow requires more power and more time than swimming with the flow. Ultrasonic flow measurement is based on this elementary transit time difference effect.

Two sensors mounted on the pipe simultaneously send and receive ultrasonic pulses.

At zero flow, both sensors receive the transmitted ultrasonic wave at the same time, i.e. without transit time delay.

When the fluid is in motion, the waves of ultrasonic sound do not reach the two sensors at the same time.

Measurement: FlowUltrasonic flow-meters

This measured "transit time difference" is directly proportional to the flow velocity and therefore to flow volume.

By using the absolute transit times both the averaged fluid velocity and the speed of sound can be calculated.

Ultrasonic flow meters measure the difference of the propagation time (transit time) of ultrasonic pulses propagating in (normally an inclination angle around 30 to 45° is used) flow direction and against the flow direction.

This time difference is a measure for the averaged velocity of the fluid along the path of the ultrasonic beam

http://en.wikipedia.org/wiki/Ultrasonic_flow_meter

Measurement: Flow

Ultrasonic flow-metersAdvantages: With homogeneous fluids, the principle is independent of

pressure, temperature, conductivity and viscosity Usable for a wide range of nominal diameters Direct meter

installation on existing pipes Non-invasive measurement No pipe constrictions, no pressure losses No moving parts. Minimum outlay for maintenance and

upkeep

Measurement: FlowCoriolis Mass Flow-meters

If a moving mass is subjected to an oscillation perpendicular to its direction of movement, Coriolis forces occur depending on the mass flow.

A Coriolis mass flow meter has oscillation measuring tubes to precisely achieve this effect.

Coriolis forces are generated when a fluid (= mass) flows

through these oscillating tubes. Sensors at the inlet and outlet ends register the resultant phase shift in the tube's oscillation geometry.

Measurement: FlowCoriolis Mass Flow-meters

The processor analyzes this information and uses it to compute the rate of mass flow.

Advantage This principle is used in a huge range of industry sectors,

including pharmaceuticals, chemicals and petrochemicals, oil and gas, food etc.

Measurement: FlowMajor issues for selecting flow-meters

Accuracy RepeatabilityLinearityReliabilityRange/SpanDynamics(Response time)SafetyMaintenanceCost

Measurement: Temp.Measurement Devices

Thermocouples Resistance Thermometers Thermistors Bimetallic Thermometers Acoustic Pyrometers Local Instruments

Measurement: Temp.Thermocouple

IT IS BASED ON ‘SEEBECK’ EFFECT WHICH SAYS THAT WHEN HEAT IS APPLIED TO A JUNCTION OF TWO DISSIMILAR METALS AN ‘EMF’ IS GENERATED WHICH CAN BE MEASURED AT THE OTHER JUNCTION

T/C Connection COMPENSATING CABLEHOT JUNCTION

TO DDC CARDS

TERMINAL END CJC BOX

Measurement: Temp.Thermocouple

Types of T/C:E,J,K,T,R,S,B K (Chromel & Alumel; Ni-Cr &Ni-Al) Type: mostly used in power plant

for low temp. application ) R (Platinum & Platinum-Rhodium) Type: Used for high temp.

application. Highly resistant to oxidation & corrosion Advantages: - Disadvantages: - - Low Cost - Sensitivity low & low voltage output - No moving parts, less likely to be broken. susceptible to noise -Wide temperature range. - Accuracy not better than 0.5 °C -Reasonably short response time. - Requires a known temperature - Reasonable repeatability and accuracy. reference

Measurement: Temp.RESISTANCE THERMOMETER (RTD)

THE RESISTANCE OF A CONDUCTOR CHANGES WHEN ITS TEMPERATURE IS CHANGED .THIS PROPERTY IS UTILISED TO MEASURE THE TEMPERATURE.

Rt = Ro (1+βdT)WHERE β = TEMP CO- EFFICIENT OF RESISTANCE ; dT = TEMPERATURE DIFFERENCEWhen discussing RTDs, following must be considered:• Wiring configuration (2, 3 or 4-wire) • Self-heating • Accuracy RTD types:• Stability 1. Platinum (Range -200 °C to 600 °C )• Repeatability 2. Copper (Range -100 °C to 100 °C ) • Response time 3. Nickel (Range -60 °C to 180 °C )

Measurement: Temp.THERMISTORS

THERMISTORS ARE GENERALLY COMPOSED OF SEMICONDUCTOR MATERIALS.THEY HAVE A NEGATIVE COEFFICIENT OF TEMPERATURE SO RESISTANCE DECREASES WITH INCREASE IN TEMP.

Making use of Negative Temperature Coefficient characteristics, thermistor and can be applied in temperature compensation, inrush current limit, precision temp. control (temp. coefficient very large compared to RTC & T/C) etc.

BIMETALLIC THERMOMETERS ALL METALS EXPAND OR CONTRACT WITH TEMPERATURE THE TEMPERATURE COEFFICIENT OF EXPANSION IS NOT THE SAME FOR

ALL METALS AND SO THEIR RATES OF EXPANSION AND CONTRACTION ARE DIFFERENT

USAGE: IN PROCESS INDUSTRIES FOR LOCAL TEMPERATURE MEASUREMENTS OVERLOAD CUTOUT SWITCH IN ELECTRICAL APPARATUS

Measurement: Temp.ACOUSTIC PYROMETER

Acoustic Pyrometer is a non-contact measurement device that obtains highly accurate instantaneous gas temperature data in any area of the boiler, helping improve combustion efficiency.

For measurement of temperatures across large spaces of known distance in a noisy, dirty and corrosive environment such as a coal-fired utility boiler, or a chemical recovery boiler.

The Velocity of Sound in a medium is proportional to the Temperature.

LOCAL INDICATION LIQUID IN GLASS THERMOMETER MERCURY IN STEEL THERMOMETER BIMETALLIC THERMOMETER

Power Plant C&I systems1.Field instruments/ input & output

instrumentsa) Various measuring instruments like Transmitters, RTD,

Thermocouples, Pr. & temp. gauges, speed & vibration pick ups etc. (Analog inputs)

b) Various Pr., Temp. & limit switches, for Interlock , protections & feedback of control element (Binary inputs)

c) Output devices like solenoids, EP converters, Positioners etc. for controlling final control element

d) Final control elements like Power cylinder, Pneumatic/ motorized actuators etc.

Power Plant C&I systems2. Control Systemsa) Various control cabinets for acquiring field signal (both

analog & binary inputs), processing the signals as per control logic and issuing output command to output devices (Binary & analog).

b) Various control desk devices like command consoles, Push button modules, indicators, recorders, CRTs, PC based Operator Work Stations (OWS) etc. for human machine interface for monitoring & control of the plant

c) Power supply system(UPS)/ chargers with battery backups to ensure uninterrupted power supply of desired quality for the control system

Power Plant C&I systems3. Analyzers The availability, reliability & efficiency of boiler unit hinge

around the close control of chemical regimes of working fluid i.e. water/steam as well as combustion in the boiler. The instruments monitoring the chemical regimes and combustion are generally called analytical instruments. These instruments fall under three category

i) Water/ Steam Analyzersii) Gas analyzersiii) Smoke monitors HIGH PURITY WATER IS ESSENTIAL TO MINIMISE SCALING CORROSION CARRY OVER EMBRITTLEMENT

Power Plant C&I systems ANALYZERS AND MEASURMENT LOCATION

a) ON LINE gas analyzers for measurement of flue gas oxygen, carbon mono-oxides, carbon di-oxides, oxides of sulpher & nitrogen at various location of boiler.

b) ON LINE analyzers for measurement of conductivity, pH, silica, dissolved oxygen, phosphate, hydrazine, chloride, sodium etc. at various points in the water & steam cycle of boiler & turbine area (SWAS-steam & water analysis system).

c) ON-LINE opacity monitors for measurement of dust concentration in flue gas

d) ON LINE analyzers for measurement of conductivity, pH, silica, dissolved oxygen etc. at various ION exchangers of DM plant .

Power Plant C&I systemsTYPICAL VALUES OF CHEMICAL PARAMETERS BEING MEASURED (SWAS)

SAMPLE PARAMETER UNIT LIMITDM WATER a) Conductivity

b) Cation Conductivity µS/cm

<0.3

Condensate pump discharge (CEP)

a) Conductivityb) Cation Conductivity µS/cm <5

<0.3

c) pH 9.0-9.2d) Na+ ppb <5ppb

e) Dissolve oxygen (DO)

ppb <10Economizer Inlet

a) Conductivityb) Cation Conductivity

µS/cm <5<0.3

c) Hydrazine ppb 10-20Boiler

watera) Conductivity µS/cm 100

b) pH 9.1-9.4

c) Silica ppb 100Sat & Main steam

a) Conductivityb) Cation Conductivity µS/cm <5

<0.3

Power Plant C&I systems4. Laboratory Instruments & Setup

Activities of C&I Lab CALIBRATION

REPAIR

TESTING with proper documentation & recordsCALIBRATION: Pressure switch , Transmitter , Gauge Temperature switch , Transmitter , Gauge Flow Transmitter Level Switch

Power Plant C&I systems4. Laboratory Instruments & Setup

REPAIR:1. ELECTRONIC CARDS3. POWER SUPPLY MODULES

TESTING:1. ELECTRONIC MODULES

2. RELAYS

3. POWER SUPPLY MODULES

Power Plant C&I systems4. Laboratory Instruments & Setupa) Different standard instruments with traceability up to national

standard . These insts. include Standard Gauges, Multimeters, Resistance boxes, mA sources, oscilloscope, signal generator etc. for calibration of measuring instruments.

b) Dead Weight tester, Comparator, Temperature bath, Vacuum pump, manometer, soldering stations etc.

c) Test benches with standard power supply sockets (e.g. 24VDC, 48VDC, 220VDC, 110VAC, 230VAC etc.) in each bench depending on requirement.

d) Laboratory should be air-conditioned with monitoring of temp., humidity and barometric pressure. Also, proper provision for handling electronic cards (floor mats, ESD protective bags/ anti static bags etc.)

Power Plant C&I systems4. Laboratory Instruments & SetupEssential Tools/ Infrastructure for Repairing & testing1. IN-CITCUIT IC TESTER2. ESD WORK STATION3. ULTRASONIC CARD CLEANER4. STORRAGE OSCILLOSCOPE5. LOGIC ANALYSER6. THERMOCOUPLE SIMULATOR7. VIDEO PATTERN GENERATOR8. EPROM PROGRAMMER

Power Plant C&I systemsC&I systems of Boiler FSSS (Furnace safeguard supervisory system) Open loop control system (interlock &

protections) of boiler auxiliaries Secondary Air Damper control system (SADC) Hydrastep for drum level measurement Measurements, Protection & Control of Coal

Feeders

Power Plant C&I systemsFSSS

FUNCTIONS OF F.S.S.S

1. FURNACE PURGE SUPERVISION2. OIL GUNS ON/OFF CONTROL3. PULVERISERS/FEEDERS ON/OFF CONTROL4. SECONDARY AIR DAMPERS CONTROL5. FLAME SCANNER INTELLIGENCE6. BOILER TRIP PROTECTIONS

Power Plant C&I systems FSSS

WHY AT ALL A PROTECTIVE SYSTEM IS REQUIRED FOR THE BOILER?

THE BOILER’S FURNACE IS CONTINUOUSLY FED WITH HIGH CALORIFIC VALUE ATOMISED FUEL WHICH IS IN THE PROCESS OF CONTINUOUS BUT CONTROLLED COMBUSTION.

COMBUSTION-THE PROCESS COMBUSTION IS A RAPID BURNING OF OXYGEN WITH FUEL RESULTING

IN RELEASE OF HEAT. AIR IS ABOUT 21% OXYGEN AND 78% NITROGEN BY VOLUME. MOST FUELS CONTAIN CARBON, HYDROGEN AND SULPHUR. A SIMPLIFIED COMBUSTION PROCESS COULD BE

CARBON+OXYGEN=CARBONDIOXIDE+ HEAT HYDROGEN+DO =WATER VAPOUR + HEAT SULPHUR +DO =SULPHURDIOXIDE+ HEAT WHICH MEANS THAT THE FINAL DESIRED PRODUCT OF THE

PROCESS IS HEAT WHICH WE REQUIRE TO BOIL THE WATER

Power Plant C&I systemsFSSS

COMBUSTION-THE PROBLEM : WHEN THIS CONTROLLED BURNING GOES OUT OF CONTROL DUE TO AN IMBALANCE IN THE FUEL/AIR RATIO, THERE IS EITHER A FUEL RICH MIXTURE OR A FUEL LEAN MIXTURE. IN BOTH CASES THE FLAME QUALITY BECOMES POOR. THERE IS A CHANCE OF FUEL ACCUMULATION WHICH CAN LATER ON IGNITE SUDDENLY AND CAUSE EXPLOSIONS.

SO FSSS IS USED FOR SAFE AND ORDERLY STARTUP AND SHUTDOWN OF BOILER THROUGH VARIOUS INTERLOCKS AND PROTECTIONS

THE PROTECTIVE SYSTEM IN THE BOILER IS DESIGNED BASICALLY TO PREVENT OCCURRENCE OF SUCH SITUATIONS BY TAKING ADVANCE ACTIONS.

Power Plant C&I systemsN.F.P.A Guide line & Boiler Protection

N.F.P.A- National Furnace Protection Association, USA

Deals with protection for various types of furnace Protection of Pulverized fuel fired boiler is governed by

Section-85c Different categories of protection: a) Mandatory, b)Mandatory & automatically generated, c)

Optional but alarm has to be there

Power Plant C&I systemsBOILER FLAME & FLAME SCANNERS

It looks rather static, but in reality the fire energy fluctuates

rapidly. The Fuel and Oxygen in the uncontrolled fire constantly burn as in small explosions and then sucks new Fuel & Oxygen to the flames. This

process causes the flame flicker.

Flicker frequency for oil flame is more than that of coal

flame.

Power Plant C&I systemsINTENSITY RELATIVE TO WAVELENGTH

Power Plant C&I systemsFLAME SCANNERS

-UV Scanners-Visible Range Scanners (Safe scan-1&2)-Used for both Oil & Coal

Flame-IR Scanners (UR600 of ABB)

SAFE FLAME SCANNER

Power Plant C&I systemsC&I systems of Turbine ATRS (Automatic Turbine Runup system) Turbine Governing System Turbovisory Instruments & turbine protections Interlock, Protection & Control of HPBP system Open loop control system (interlock & protections)

of turbine auxiliaries Interlock & protections of Seal Oil & Stator water

system

Power Plant C&I systemsC&I systems for control & MIS-Automatic Control System (ACS)

-DATA Acquisition system(DAS)

-Distributed Digital Control Monitoring and Information System

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOP

PROCESS: Process refers to the method of changing or refining raw materials to create the desired end product. The raw materials may undergo physical, chemical, or thermal state changes during the Process.

Process is of Two Types : A) Continuous and B) Batch Continuous Process is one where the change of state of Input into

Output occurs continuously. Ex.: Power Plant Process, Petroleum Industry etc. Batch Process is one where a Batch of the Product is produced

and the Process stops till production of next Batch is started. Ex.: Automobile Production

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOPPROCESS CONTROL: Process control techniques are developed

over the years to have Quality of the end product Economy of production Ability to cater to emergencies and bring the process to safe

shutdown.

CONTROLLED CONDITION: The physical quantity or condition of a process or machine which is to be controlled

CONTROL SYSTEM: An arrangement of elements interconnected and interacting in such a way that it can maintain some condition of a process or machine in a prescribed manner

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOPOPEN AND CLOSED LOOP CONTROL: A Closed Loop Control (CLCS) is one where a

Process Variable is measured, compared to a Set Value and action is taken to correct any Deviation or Error from Set Value. The continuous Measurement of PV and its’ comparison to Set Point closes the Loop.

An Open Loop Control(OLCS) is one where the PV is

not compared with Set Value and action taken, but action is taken without regard to conditions of PV.


OPEN LOOP CONTROL:Open Loop Control is accomplished by the following means:

Group Control Sub-Group Control Sub-Loop Control Drive Level Control Programmable Logic Control(PLC)

Group Control : Start and Stoppage of a Group of equipment is accomplished by Group Control(GC).

Ex. :CEP GC, Equipment Cooling GC etc.


OPEN LOOP CONTROL: Sub-Group Control : Start and Stoppage of an equipment with its’

associated auxiliaries in Step-Sequence manner is done by Sub-Group Control. Operator intervention is not required in Sub-Group Control(SGC).

Sub-Loop Control: Start and Stoppage of auxiliaries of an equipment is carried out by Sub-Loop Control(SLC)

Drive Level Control : Start and Stop or Opening and Closure of a Drive is carried out by Drive Control. The Drive logic shall have Protection, release ,auto and manual commands and these are executed as per pre-determined logic.


CLCS TERMINOLOGY: Desired Value or Set Point : The value of the variable/parameter

which needs to be controlled at the required condition. Process Variable(PV) : The present value of the Parameter of Process

at that particular instant. This is sometimes referred as Measured Value.

Error/Deviation : It is the Difference between Set Point and Process Variable, and can be +ve or –ve. It has three components: a) Magnitude b) Duration and c) Rate of change.

Controller : A Controller is a device that receives data from a Measurement Instrument, compares the data with the Set Point and if necessary, signals a Control element to take Corrective action. This Corrective action ensures that the PV shall always be maintained at the Set Value.

The Controller can be a) Electronic, b) Pneumatic and c) Hydraulic type.


Controller types: Functionally, Controllers can be a) Continuous and b) Step Controllers. Depending on the control loop; controller action can be

adjusted as (i) Direct acting:-Increase of process value increases controller output

(ii) Reverse acting:- Increase of process value decreases controller output

Control Element : The Control or Correcting Element is the part

of the Control System that acts to physically change the Manipulated Variable.

Ex. : Control Valves, Louvers or Dampers, Solenoids, Pump Motors etc.


Bump less Transfer : The arrangement where the transfer from auto to manual mode does not affect the process.

Proportional Control : The Proportional (P) action responds only to a change in the magnitude of Error(e) i.e. controller output changes by an amount which is proportional to error.

Output change of Controller in % = (Error change in %)(Gain), where Gain is called the Controller gain. The reciprocal of Gain is termed as Proportional Band(PB) and is expressed in %.

Proportional Band(PB): The change in deviation required to cause the output of the controller to change from one extreme to the other.

Integral Control : In Integral Control, the Controller output is a function of the Duration of Error(e).


Hence, the Controller output is the time Integral of Error and the time set is Integral Action Time(IAT) i.e. IAT can be defined as time taken for the integral action to change output by the same amount as the proportion action .

Usually, both P and I Controls are combined and the Controllers are

tuned to minimize Error(e) and controller is termed as PI controller.

Derivative Control : Derivative or Rate Controller’s output is Proportional to the rate of change of Error(e). The Control action is termed as D. The action is to apply an immediate response that is equal to the P+I action that would have occurred some time in the future.

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOPImportant Closed Loop Controls in a Thermal Power Plant: a) Furnace Draft Control b) Boiler Drum Level Control c) HOT well & D/A level control d) Main Steam Temperature Control e) Air and Fuel Flow to Boiler Control f) SH & RH spray control g) Coordinated Master Control(CMC) h) Turbine Speed, Pressure and Load Control

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOPCoordinated Master Control This is an integrated automatic control of unit operation. There is

a continuous co ordination between boiler and turbine control to maintain a balance between steam generation and steam consumption.

• Boiler Follow Mode (BFM)• Turbine Follow Mode (TFM)• Co-ordinated Master Control (CMC)• Runback Mode

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOPBoiler Follow Mode (BFM)• Unit load control from turbine local load set point• Change in turbine load set point will modulate turbine CVs• Boiler master output gets corrected to maintain throttle pr dev.• Boiler control will follow turbine control• BLI signal as feed forward signal for boiler firing rate control• Result - Boiler acts as throttle pr controller where turbine is in load

controller mode

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOPTurbine Follow Mode (TFM)• Unit target load set point goes to boiler master• Change in BLI will modulate turbine CVs• Boiler master output gets corrected to maintain Unit load dev. • Turbine control will follow boiler control• Load deviation as feed orward signal for boiler firing rate control• Result - Boiler acts as load controller where turbine is in pressure

controller mode

Power Plant C&I systemsAUTOMATIC CONTROL SYSTEM & POWER PLANT CONTROL LOOPCoordinated Master Control• Unit load is set from unit master.• Unit master demand is limited by unit capability , TSE margins and unit

max/min load set points.• Unit target load is derived from unit master after the limitations.• Unit target load is used as feed forward signal to the boiler firing rate

control. • Turbine control utilises the unit load as turbine load set point after adapting

the same by steam generation delay.• In TG throttle pressure is maintained by correcting the BMD output

depending on the throttle pr dev. • Result: Balance is achieved between steam generation and steam

consumption PROPER COORDINATION BETWEEN BOILER CONTROL AND TURBINE CONTROL

Power Plant C&I systemsDATA ACQUISITION SYSYTEM-DAS

WHY DAS IS REQUIRED IN THERMAL POWER PLANTS ? SAFE & RELIABLE OPERATION OF THE UNIT OR EQUIPMENTS ASSIST CONTROL ROOM OPERATORS BY PROVIDING TIMELY

ANNUNCIATION OF ALL ABNORMAL CONDITIONS PROVIDE DETAILED INFORMATION ON THE PLANT PERFORMANCE PROVIDE MANAGEMENT WITH ACCURATE RECORDS ON THE PAST

PLANT PERFORMANCE FOR ANALYSIS

Power Plant C&I systemsDATA ACQUISITION SYSYTEM

3 MAJOR FUNCTIONS OF DAS: DATA ACQUISITION DATA PROCESSING DATA REPRESENTATION

The Major Parts Process Control Units ( PCU ) Computer Interface Unit ( CIU ) Termination Units ( TU ) Buffer Terminal Cabinets ( BTC )


TYPES OF DATA (Input): Analog & Digital

Analog inputs: 1. Thermocouple Input ( mV )

K-Type T/C ( Cr-Al ) : For temp < 600 Deg C& used in Flue Gas path after FSH outlet.

R-Type T/C ( Pt-Pt-Rh ) : For temp > 600 Deg C used in PSH & FSH region of FG path.

2. RTD Input ( Resistance ) Pt-100 RTD : For Brg. Temp measurement. Cu-53 RTD : For HT motor & Generator Stator winding

temp. measurement.


Analog inputs: 3. 4 – 20 Ma Input

Coming from Pr. / Flow Transmitters. Coming from Signal Distribution Cards of automatic control

system 4. 0 – 10 Volt Input Coming from ATRS cabinets Used for Turbine Brg. Temp. /Vibration measurement.

DIGITAL INPUTS These are coming directly from switches or relay contacts

of other systems (FSSS, ATRS, ACS etc.)


DIGITAL INPUTS (TYPES) LOW RESOLUTION : The scanning time of inputs is 1

second. HIGH RESOLUTION : The scanning time is 1

millisecond. These are called Sequence Of Events ( SOE ) Inputs.

PULSE INPUT : For calculation of Total Coal Flow, Total Air Flow etc.


FUNCTIONS OF DAS: Alarm Management. Production of hardcopy print outs in different printers. Operator Guidance Messages. Graphic Displays of plant sub-systems. Trending of analog variables on recorders. Sequence Of Events ( SOE ) recording following unit /

equipment trip conditions. Efficiency calculations


DATA PROCESSING: It has the following parts COMPUTER PROCESSING UNIT ( CPU ) BULK ( SOLID STATE ) MEMORY WITH BATTERY BACKUP MAGTAPE UNIT COMMUNICATION CABINET & MODEM MOVING HEAD DISC DRIVE VIDEO HARD COPIER TREND RECORDER UNIT CONTROL DESK & PROG. ROOM CRT PRINTERS


Features: REAL TIME VARIABLE CALCULATION Summing, Subtraction, Maximum , Minimum,

Averaging, Hourly & Daily integration, rate of changes & comparison of limits etc.

ON-LINE DATABASE EDITION 1. Assign points to any process parameter 2. Scan, Off-scan , Delete , Activate , inactivate a process parameters , calculated points when reqd.3. Change the Engg. Unit4. Change the range , alarm limits & dead bands5. Change the scan frequency6. Review total analog and digital points depending on its quality flag like alarm , channel failure , off-scan etc.


ALARM MANAGEMENT: All the analog points which cross their normal limits or all the

digital points which go into their alarm state come on the alarm CRT with associated time & blink as long as the alarms remain unacknowledged.

Alarm will come in RED colour If all the pages are full (normally no. of alarm pages & alarm per

page is predefined) and any new alarm comes , then oldest alarm will disappear from the alarm page as FIFO basis

Alarm print out will be available in alarm printer


DATA REPRESENTATION: Printed outputs of displays /collection of data in different formats

like :1. Copy Screen2 Alarm Print out3. Log Print out

CRT Displays1. Alarm CRT display2. Utility CRT display


DATA REPRESENTATION:TYPES OF TREND LOG PRINOUTS

TIME ACTIVATED EVENT ACTIVATED DEMAND LOGS SOE PRINTOUTTIME ACTIVATED LOG: Automatic Triggered Logs Sample frequency is 1 Hour.(Normally) Time of trigger can be specified


TIME ACTIVATED LOG: Max. 15 nos. of points can be assigned Normally printed in the logging printer in UCB Examples :

1. Shift Log2. Efficiency Log3. Boiler Drum / Tube Metal Temp. Log4. FSH / RH Metal temp. excursion Log

EVENT ACTIVATED LOG: Automatic Triggered Logs Used for Unit or Equipment Outage Analysis Minimum Sample frequency is 10 seconds.


EVENT ACTIVATED LOG: Max. 36 points can be assigned in a log Logs are triggered by a Trip flag Normally printed on Logging Printer in UCB Pre & Post triggered points can be specified Examples :

1. Post Trip Analysis Log ( PTL ) 2. TG. Shutdown Analysis Log 3. Boiler Startup Log. 4. Turbine / Generator Diagnostic Logs


DEMAND LOG: Not Automatic Triggered Logs

Logs can be printed on operator’s demand

Sample frequency is generally 1 Hour.

Logs are printed in Logging Printer in UCB

Power Plant C&I systemsDATA ACQUISITION SYSYTEMSEQUENCE OF EVENTS ( SOE )

THE MAIN FEATURES ARE: Determines First Cause Of Trip Determines sequence of events or alarms Scanning Time is 1 millisecond. It is a Stand Alone System Max. 256 nos. of Protection related digital points can be assigned Automatic Triggered when any point in alarm

Power Plant C&I systemsDDCMIS

WHAT IS DDCMIS ? DISTRIBUTED DIGITAL CONTROL MONITORING & INFORMATION

SYSTEM

Distributed means there is no centralized control and control is spread across multiple units

Digital means processing of process information is done in digital form using micro-processor based hardware

MIS interfaces the human with process using computers


TECHNOLOGICAL BACKGROUND PROGRESS OF INSTRUMENTATION USED TO IMPLEMENT AUTOMATIC

PROCESS CONTROL LOCAL PNEUMATIC CONTROLLERS MINIATURIZED AND CENTRALIZED PNEUMATIC CONTROLLERS AT

CONTROL PANELS AND CONSOLES SOLID-STATE CONTROLLERS COMPUTERISED CONTROLS DISTRIBUTED MICROPROCESSOR BASED CONTROL


Components

MAN MACHINE INTERFACE & PROCESS INFORMATION SYSTEM

DATA COMMUNICATION SYSTEM (DATA HIGH WAY)

CONTROL SYSTEM


MAN-MACHINE INTERFACE AND PLANT INFORMATION SYSTEM (MMIPS) LATEST STATE-OF-THE-ART WORKSTATIONS AND SERVERS BASED ON OPEN-

ARCHITECTURE AND INDUSTRY STANDARD HARDWARE AND SOFTWARE TO ENSURE BETTER CONNECTIVITY.

e.g. HARDWARE FROM COMPAQ/DIGITAL, HP, SUN MICRO-SYSTEM OR OTHER MAJOR SUPPLIERS (LESS DEPENDENCE ON THE C&I SYSTEM SUPPLIER IN THE LONG RUN)

OPERATING SYSTEM WINDOWS-NT, OPEN-VMS OR UNIX. PROVISION OF LVS CONNECTION TO OTHER SYSTEM THROUGH STATIONWIDE WAN


MMIPIS FUNCTIONALITIES

VARIOUS PLANT EQUIPMENT OPERATION

OPERATOR INFORMATIONS THROUGH VARIOUS DISPLAYS

ALARMS, LOGS, HISTORICAL AND LONG TERM STORAGE.

PERFORMANCE AND OTHER CALCULATIONS


DATA COMMUNICATION SYSTEM LOCAL SYSTEM BUS – It is just lines on the backplane of control

panel to which all the modules are connected directly. It serves as communication medium between the modules.

INTRAPLANT BUS(IPB) – It is a coaxial cable which runs through all the panels of control system and interconnects them.

LOCAL AREA NETWORK(LAN) – It is a network of computers which are connected to a single point (HUB).

FOR ALL BUSES REDUNDANCY IS PRESENT


CONTROL SYSTEM

FUNCTIONAL DIVISION SG-C&I SYSTEM TG-C&I SYSTEM BOP-C&I SYSTEM

HARDWARE COMPONENTS POWER SUPPLY CONTROL PANEL ELECTRONIC MODULES


PROGRAMMING & MMIPIS M & SCONFIGURATION SYSTEM CLOCK

SG- C&I BOP- C&I TG- C&ISYSTEM SYSTEM SYSTEM

DCS

CONTROL SYSTEM


SG-C&I SYSTEM BURNER MANAGEMENT SYSTEM (BMS) SOOT BLOWER CONTROL SYSTEM (SBC) SECONDARY AIR DAMPER CONTROL SYSTEM (SADC) AUXILIARY PRDS CONTROLS (APRDS)

TG-C&I SYSTEM ELECTRONIC TURBINE PROTECTION (ETP) AUTOMATIC TURBINE RUN-UP SYSTEM (ATRS) AUTOMATIC TURBINE TESTING SYSTEM (ATT) ELECTRO- HYDRAULIC TURBINE CONTROL SYSTEM (EHTC) TURBINE STRESS CONTROL SYSTEM (TSC) LP BYPASS SYSTEM (LPBP) HP BYPASS SYSTEM(HPBP) GLAND STEAM PRESSURE CONTROL GENERATOR AUXILIARY MONITORING PANEL (GAMP)


BOP-C&I SYSTEM CONSISTS OF OPEN LOOP CONTROL SYSTEM (OLCS) AND CLOSED LOOP

CONTROL SYSTEM (CLCS)

OLCS - THE SEQUENCE CONTROL, INTERLOCK OF ALL THE PLANT SYSTEMS WHICH ARE NOT COVERED IN THE SG-C&I AND TG-C&I. THIS INCLUDES MAJOR AUXILIARIES LIKE FD/ID/PA FANS, AIR-PREHEATER, BFP/CEP/CWP/ BCWP , DMCWP/CLCWP AND ELECTRICAL BREAKERS.

CLCS - THE MODULATING CONTROL FOR VARIOUS IMPORTANT PLANT PARAMETERS, LIKE FW FLOW (DRUM LEVEL), FURNACE DRAFT, COMBUSTION CONTROL (FUEL FLOW AND AIR FLOW), PA HDR PRESSURE CONTROL, DEAERATOR/HOTWELL/HEATER LEVEL CONTROLS ETC.


WHY DDCMIS ? VERY HIGH FLEXIBILITY FOR MODIFICATION IN CONTROL STRATEGY VERY HIGH SELF-DIAGNOSTIC VERY LOW DRIFT (ONLY IN I/O CARDS) , HENCE NO NEED OF FREQUENT

RE-CALIBRATION MUCH HIGHER RELIABILITY (BASED ON MTBF) BETTER LONG TERM SUPPORT DUE TO CHANGING TECHNOLOGY MUCH BETTER OPERATOR INTERFACE


SALIENT FEATURES OF DDCMIS INTEGRATED PLANT CONTROL FOR SG, TG AND BALANCE OF

PLANT CONTROL IT MAY BE REMEMBERED THAT HISTORICALLY THE TERM DDCMIS

USED REFER TO THE SO-CALLED “BOP-C&I” . THE SG-C&I, i.e. FSSS etc. TG-C&I i.e. ATRS, TURBINE PROTECTION etc. ORIGINALLY WERE NOT CONSIDERED UNDER DDCMIS OR DCS AS PER MANY SUPPLIERS. ONLY RECENTLY THE TYPE OF SYSTEMS FOR ALL THE SYSTEMS HAVE BECOME SIMILAR (WITH SOME DIFFERENCE WHICH WILL BE DISCUSSED LATER), WE TEND TO CONSIDER THESE SYSTEMS UNDER DDCMIS.


SALIENT FEATURES OF DDCMIS INTEGRATED PLANT OPERATION THROUGH FULLY INTERCHANGEABLE

OPERTAOR WORK STATIONS (OWS) FOR SG, TG AND BALANCE OF PLANT PROVISION OF EXTENSIVE SELF-DIAGNOSTICS USE OF LARGE VIDEO SCREENS FOR PROJECTIONS OF VARIOUS PLANT

MIMICS ETC. PROVISION OF FAULT ALARM ANALYSIS TO GUIDE THE OPERATOR TO THE

MOST LIKELY EVENT PROVISION OF ADEQUATE RELIABILITY AND AVAILABILITY WITH PROPER

REDUNDANCY IN SENSOR, I/O AND CONTROLLER LEVELS.

Power Plant C&I systemsGlobal & National Power Scenario

Global:Global electricity consumption 69% higher in 2020 than 200380% of energy provided from thermal sources Emerging trend from Thermal to Hydel and Renewable Energy sources

Indian:Total installed capacity only 1362 MW in 1947Per Capita consumption 631 units (2005-06) only with installed capacity of 1,77,000 MWGDP growth of 8%, power growth required 10%To add 1,00,000MW capacity by 2017Liberalizations of the sector

Reliance Power Practices to achieve goal

KEY THRUST AREASZero Human ErrorImplementation of trip committee recommendations judiciously / rigorouslyIdentification of trip committee recommendations of other stations which are relevant and implement them Implementation of operation memorandum wherever applicableDissemination of information about best practices followed across Reliance Power and other Power StationsProviding proper environment for C&I equipment to reduce probability of card and equipment failure

C&I Trip Trend

2009-10: FORCED OUTAGE DISTRIBUTION (COAL)

9%22%

28%

2%9%

17%

7% 2% 4%

Coal 09-10Relay Malfunction

Tx / Sw /Fld Dev

Control System

EHC / ATRS

Power Supply / CableSoftware / Card failureHuman Error

UPS

RTD / Tc

INFERENCE : 2009-10 C&I OUTAGE ANALYSIS

Major factors contributing to C&I outage in 2009-10:

1. Control System related failure

2. Field Device Failure

3. Soft ware/Card Failure

4. Power Supply/Relay failure

5. Human error

BEST PRACTICES COMPILED/ADOPTED IN Reliance Power C&I

All ‘unit protections’ are provided with 2/3 logic and audio visual alarm is provided on 1/3 to operator on actuation of any one sensor wherever possible with proper approval.

Use of headless RTD in tripping circuit of ID/PA/FD fans & BFPs.

Resistance mapping of critical solenoids including cable during overhauls and monitoring trend to identify any defects.

Marking of trip related devices and Junction Boxes marked in RED color.

Regular calibration of all important instruments which have a bearing on unit safety, reliability and efficiency. Instruments are calibrated against standard instruments with traceability to NABL.


For handling of electrostatic sensitive electronic hardware, electrostatic bags, wrist straps and other ESD handling devices are employed in control panels and lab. All Laboratories are provided with ESD proof workstations.

Disable removable drives of servers and workstations.

Single source responsibility for software backup of DCS and storage in fire proof cabinets in two different locations.

Detailed work instruction are prepared and followed for working on all trip related devices.


A single source responsibility is fixed for the generation and maintenance of system passwords so as to maintain system security

Internal quality inspection for critical checks during overhauls to ensure quality in overhaul works

Near miss situations are monitored and analyzed. The learning from this area used to formulate strategies to avoid spurious outages.

All power supply voltages are monitored with a fixed periodicity and maintained within /- 10% of the rated value.

Other important actions taken for forced outage reduction

Rerouting of control & power cables in hot zones

Panel power supply monitoring in regular intervals.

CER/UCB temperature and humidity monitoring online. Insisting for performance of the A/C system

Checking and tightening power supply cables during overhaul

Ensuring healthiness of cabinet cooling fans.

Other important actions taken for forced outage reduction

Panel cooling fans supply segregation from system supply with MCB / fuse.

Cleaning of air filters on panels periodically

Servo valve replacement/ servicing in hydraulic drives.

Individual fuse protection in 220VDC MFT for HOTV, LOTV, HORV, Scanner emergency air damper solenoids

role of c & i in thermal power plant

Engineering