17648889 Introduction to Power System Protection Relays

P. GOPALA KRISHNAADE/400KV/APTRANSCO

Power Systems Protection -Introduction


Power Evacuation Substation

Transmission Substation

Switching Substation

Distribution Substation

Power System Components

1. Generators2. Transformers3. Transmission Lines4. Feeders5. Motors6. Capacitor Banks7. Bus Bars8. Reactors



Why we need the Protection ?To detect abnormalities (faults).

To eliminate such abnormality by

isolating smallest portion of the system

in a shortest period of time.

To prevent injury to personnel.

To prevent damage to Equipment.

Enable Continuous service in

undamaged part of the network.


Protective Relay – What should it do ?Monitor system parameters continuously

(V, I, P, F)

Operate quickly when necessary

(Dependability)

Should not operate wrongly

(stability, discrimination)

To trip or not to trip ?


Protective System – What are the Requirements?SpeedThe relay must operate at the required speed. It should neither be too slow which may result in damage to the equipment nor should it be too fast which may result in undesired operation. Damage can be Minimised.

SensitivityThe relaying equipment must be sufficiently sensitive so that it operates reliably when required under the actual conditions that produces least operating tendency and to detect all possible Shunt and series Faults.

SelectivityThe relay must be able to discriminate (select) between those conditions for which prompt operation is required and those for which no operation, or time delayed operation is required. Isolate only Faulty Section without disturbing Healthy Section.

ReliabilityThe most important requisite of protective relay is reliability since they supervise the circuit for a long time before a fault occurs; if a fault then occurs, the relays must respond instantly and correctly. The Operation Capability of the Protection System is summerised in “ reliability”, which includes both the security in fault clearance and the security against undesired clearances. The security in fault clearance is called dependability and the security against undesired clearances is called Security.


Protective Relay Scheme – What is it ?

A Protective RelayCT / CVT / PT(EMVT)Auxiliary Power Supply (24 V to 240 V AC/ DC)Switching Device ( Breaker/ Isolator / Contactor)Trip CoilAlarm / Trip contactControl Wiring


Power System - Faults

CurrentOver LoadOver CurrentEarth FaultCurrent UnbalanceDir. Over CurrentDir. Earth Fault

VoltageOver VoltageUnder VoltageVoltage UnbalanceNeutral shift

FrequencyOver FrequencyUnder FrequencydF/dT

PowerActive powerReactive powerOver powerUnder powerReverse power

ComputedOver fluxingLoss of fieldDifferential Over CurrentRestricted E/FUnder Impedance

Control/ManagementSynchronisingLoad sharingIslandingLoad shedding

DC Relays


Protection – ANSI Codes

Code numbersUsed to denoteProtectionsOn a SLD


Power System – Fault Handling

Trip & Isolate

Breaker is tripped on fault

Faulty section is isolated

Control & RegulateBreaker is not trippedCorrective actions Generated on line


Relay operation when a fault occurs

Each Relay should Protect a specific Zone in the System.

If fault is inside its Zone, Relay should operate and isolate the faulted Zone.

If fault is outside zone, Relay should not operate,

Some other Relay should operate and isolate


What happens when a fault occurs

Fault current flows through number of Relays.

Some of these Relays will start to operate.

Only one Relay related to particular fault should trip and interrupt the fault current.

Remaining Relays will reset after above.


Protection Relays – Inputs / Out puts

Inputs

Current CTsVoltage PTsFrequency PTsPower CTs + PTs

Outputs

Trip Contact


Protection Relays – Settings

Pick up setting Low setHighset

Time delay setting Definite timeInverse time

% of CTRating

TMSSetting


Power System – Trip time characteristics

I/Is

t

10

1.3 or3.0 sec

I/Is1.4LS

Power System – Trip time characteristics

I/Is

t

10

1.3 or3.0 sec

50 msec

6HS

1.4LS


Typical Inverse Time Delays


0.710.961.501.932.704.5013.50Very Inverse 1.5 sec

2.292.543.003.333.875.0310.13Normal Inv 3 sec

0.991.101.301.441.682.1804.39Normal Inv 1.3 sec

TIME MULTIPLIER SETTING – TMS : 1.00

0.200.360.811.272.285.3326.66Extremely Inverse

I/Is=20I/Is=15I/Is=10I/Is=8I/Is=6I/Is=4I/Is=2

ApplicationSLD representationFront panel ControlsBack Panel terminationsInputs / Outputs / RatingsSettings (Inside)Settings (on front panel)Installation & wiringCommissioningTesting (Front panel)Testing (SCITS)Cat . No.

Things you should know


EVALUATION OF

PROTECTIVE RELAYS

PREPARED BYGOPALA KRISHNA PALEPU

ADE/MRT(PROTECTION)

1 ST GENERATIONFIRST GENERATION RELAYS :

THESE ARE ELECTRO MAGNETIC RELAYS

IN THIS NO OF ELECTROMAGNETIC RELAYS PROVIDED FOR ARRIVING

A SPECIFIC FUNCTION i.e EACH FUNCTION OF THE SCHEME HAVING A

SEPARATE RELAY. COMBINING ALL IS CALLED ONE PROTECTION

FUNCTION. NO OF RELAYS ARE MORE AND SPACE OCUPATION IS

MORE AND INTER CONNECTION WIRING DIAGRAM IS MORE.

DISADVANTAGES: ELECTROMECHANICAL RELAYS HAVE A LOT OF

MECHANICAL PARTS, WHICH MAY BECOME CLOGGED WITH DIRT OR

CORRODED DUE TO ENVIRONMENTAL CONDITIONS, AFFECTING BOTH

OPERATION, CALIBRATION AND MOVEMENT OF THE DISKS. IT

REQUIRES PERIODICAL MAINTANENCE AND ADJUSTMENT.

1 ST GENERATIONNEXT MODIFICATION :

ELECTRO MAGNETIC RELAYS WITH STATIC COMPONENTS

IN THIS SOME OF THE FUNCTIONS ARE DERIVED FROM STATIC

COMPONENTS PROVIDED ON THE PCB. IN THIS QUANTITY OF

ELECTROMAGNETIC RELAYS ARE REDUCED. COMBINING ALL IS

CALLED ONE PROTECTION FUNCTION. QUANTITY OF RELAYS ARE

REDUCED AND SPACE OCUPATION IS REDUCED SOME WHAT.

DISADVANTAGES: THE PCBs ARE MADE WITH TRANSISTORS AND ARE

BROUGHTOUT ITEMS WITH DIFFERENT MAKE. AFTER SOME TIME

THESE ARE TO BE REPLACED FOR CORRECT OPERATION WITHOUT

DRIFT. THE PCBs & COMPONENTS PERFORMANCE MAY BE AFFECTED

DUE TO DIST & DIRT. IT REQUIRES PERIODICAL MAINTANENCE AND

ADJUSTMENT.

2 ND GENERATIONSECOND GENERATION RELAYS :STATIC RELAYS WITH TRANSISTORSIn this all of the functions are derived from static components provided on the PCB. In this initially each function is derived with separate static relay. Quantity of static relays are more but space occupation is less. Combining all is called one protection function. Inter connection wiring diagram is still not reduced. DISADVANTAGES: Static relays generally employ a lot of electronic components made by other manufacturers. If these electronic components are not tested with rigorous quality control, the chances of failure of components during the relay life time may exist. A reliable DC power source within the relay, to electronically measure circuits has to be generated from available external power sources. Most of the static relays employ series, shunt, or switched mode power supply designs. For a variety of reasons, if these power supplies fail, the measuring circuits are inoperative and the relay is dead for any measurements. No protection is available to the network. Most of the static relays in use do not have the means to detect the failure of power supply and initiate an alarm. It requires periodical Maintenance.

2 ND GENERATIONNEXT MODIFICATION :

STATIC RELAYS ON SINGLE PCBIN THIS ALL OF THE FUNCTIONS ARE DERIVED FROM STATIC COMPONENTS PROVIDED ON THE PCB. IN THIS ALL STATIC RELAYS ARE TAKEN TO ONE MASTER PCB AND EACH FUNCTION PCB WILL BE ADD ON CARD TYPE. SO TOTAL RELAY IS ONE BUT FOR EVERY FUNCTION IS PCB IS AVAILABLE AND CONNECTED TO MAIN PCB. SPACE OCCUPATION IS LESS. COMBINING ALL IS CALLED ONE PROTECTION FUNCTION. NO INTER CONECTION WIRING. THIS IS PART OF MAIN PCB. DISADVANTAGES:DISADVANTAGES ARE SAME AS ABOVE.

3 ND GENERATIONTHIRD GENERATION RELAYS :

STATIC RELAYS WITH ICsIN THIS NO OF COMPONENTS ARE REDUCED AND BROUGHT OR BUILT IN ONE INTEGRATED CHIP. DUE TO THIS THE RELAY SIZE IS REDUCED AND SOME OF THE FUNCTIONS ALSO TAKEN IN TO ONE INTEGRATED CHIP. THIS ALSO BUILT IN ONE PCB. ALL OF THE FUNCTIONS ARE DERIVED FROM STATIC COMPONENTS PROVIDED ON THE PCB. IN THIS ONLY MASTER PCB IS AVAILABLE, NO SEPARATE PCB FOR EACH FUNCTION , ALL ARE INTEGRATED IN ONE PCB. PROBLEMS ARE SOME WHAT REDUCED. SPACE OCCUPATION IS LESS. ONE PROTECTION FUNCTION ONLY ONE RELAY AND ALL FUNCTIONS ARE INTEGRATED. NO INTER CONNECTION WIRING DIAGRAM.

3 ND GENERATION

NEXT MODIFICATION :

SEMI NUMERIC RELAYSIN THIS SOME FUNCTIONS ARE CAN BE PROGRAMMABLE AND INTERFACE THROUGH PC. SOME ICs ARE HAVING THE FACILITY TO INTERACT THROUGH COMMUNICATION PORT. IT IS SOME WHAT MODIFICATION TO IC BASED RELAYS. IN THIS SOME FUNCTION CAN BE ENABLED AND DISABLED, BASED ON THE REQUIREMENT.

4 ND GENERATION

MICROPROCESSOR BASED NUMERICAL RELAYSIN THIS ALL OF THE FUNCTIONS ARE BROUGHT ON ONE IC. THE FOURTH GENERATION PROCESSOR-BASED RELAYS, DO HAVE THE WATCHDOG FEATURE, WHICH FACILITATES THE CHECKING OF POWER SUPPLY FAILS, CLOCK FREQUENCIES, AND OTHER PATTERNS. MOST OF THESE RELAYS HAVE AUTO TEST FEATURES WHICH TEST THE ELECTRONIC CIRCUIT FUNCTIONS AT REGULAR INTERVALS & AUTOMATICALLY.

MICROPROCESSOR BASED RELAYS

BACK GROUND WORK

ADVANTAGES & DISADVANTAGES

OPERATIONS & ALGORITHMS IN MICROPROCESSOR

FUNCTIONAL BLOCKS & OTHER HARDWARE OF MICROPROCESSOR BASED RELAY

FILTERING TECHNIQUES

TESTING OF MICROPROCESSOR RELAYS

MICROPROCESSOR BASED RELAYS - BACKGROUND WORK

1960sA FEW CONCEPTS WERE PROPOSED

HARDWARE WAS VERY EXPENSIVE

BENEFITS OF MICROPROCESSORS FOR RELAYS WERE NOT CLEAR

IEEE ARTICLE “FAULT PROTECTION WITH A DIGITAL COMPUTER” OUTLINED THE FEASIBILITY & PROBLEMS ASSOCIATED IN S/S PROTECTION WHEN A DIGITAL COMPUTER IS USED.


1970sTWO PAPERS WERE PUBLISHED“DIGITAL CALCULATION OF IMPEDANCE FOR TRANSMISSION LINE PROTECTION”“ 3 PH TRANSMISSION LINE PROTECTION WITH A DIGITAL COMPUTER”

PROMINENT MANUFACTURERS LIKE WESTINGHOUSE, IBM STARTED INVESTIGATING S/S COMPUTER SYSTEMS

PHILADELPHIA ELECTRIC & GE INITIATED PROJECTS ON DIGITAL TECHNIQUES FOR PROTECTION

VARIOUS ALGORITHMS WERE DERIVED FOR DIGITAL CALCULATION OF PROTECTION PARAMETRS

EXPERIMENTAL SYSTEMS WERE BUILT BY GE & WESTINGHOUSE TO CHECK ALGORITHMS

FIRST GENERATION OF MICROPROCESSOR BASED RELAYS BUILT


1980sMAJOR MANUFACTURERS LIKE ABB, GE, GEC , TOSHIBA, SIEMENS START DESIGN & SALES OF BROAD RANGE OF PRODUCTS FOR POWER SYSTEM PROTECTION

MICROPROCESSOR IMPROVES PERFORMANCE SPECS FOR OPERATION IN INDUSTRIAL ENVIRONMENT

MANY PLC BASED SYSTEMS ARE COMMISSIONED IN INDIA BY L&T, SIEMENS, ECIL ETC.

MANY ELECTRICITY BOARDS & PROCESS PLANTS IN INDIA START USING MICROPROCESSOR BASED INSTRUMENTS

THE WORD SCADA GETS POPULAR IN INDIA

PGCIL GOES IN FOR MICROPROCESSOR BASED DISTANCE RELAYS IN INDIA


1990sABB & GEC ALSTOM INTRODUCED RANGE OF MICROPROCESSOR BASED RELAYS FOR ALL UNIT PROTECTIONS

MAJOR MANUFACTURERS LIKE ABB, GE, GEC , TOSHIBA STARTS DESIGN & SALES OF BROAD RANGE OF PRODUCTS FOR POWER SYSTEM PROTECTION

MANY ELECTRICITY BOARDS & PROCESS PLANTS IN INDIA START USING MICROPROCESSOR BASED INSTRUMENTS

PGCIL GOES IN FOR MICROPROCESSOR BASED DISTANCE RELAYS IN INDIA

MICROCONTROLLERS / DSPs ARE INTRODUCED IN LATE 90s BY HARDWARE MANUFACTURERS WHICH HAVE IMPROVED THE SPEED OF OPERATION.

PARAMETER NUMERIC CONVENTIONAL

ACCURACY 1% 5% / 7.5%BURDEN < 0.5 VA > 5 VASETTING RANGES WIDE LIMITEDMULTI FUNCTIONALITY YES NOSIZE SMALL LARGEFIELD PROGRAMMABILITY YES NOPARAMETER DISPLAY YES NOSYSTEM FLEXILBILITY YES NOCO-ORDINATION TOOLS MANY TWOCOMMUNICATION YES NOREMOTE CONTROL YES NOSPECIAL ALGORITHMS MANY LIMITEDSPECIAL PROTECTIONS YES NOSELF DIAGNOSTICS YES NO

ADVANTAGES OF NUMERIC RELAYS

DIS-ADVANTAGES OF NUMERIC RELAYS

SOFTWARE INTENSIVE

OBSOLESENCE RATE

EMI / EMC PROBLEMS

SERIAL NATURE

PROTECTION ALGORITHM

MEASUREMENMT METHOD

TRIP TIME CALCULATION

GOOD FILTERING CHARACTERISTIC(HARMONICS, NOISE, DC SHIFT)

FAST TRIP DECISION

FUNCTIONAL BLOCKS OF A NUMERIC RELAY

ANALOGINPUT

SU-SYSTEM

DIGITALINPUT

SUB-SYSTEM

POWER SUPPLY

MICROPROCESSOR

COMMUNICATIONINTERFACE

RAM

ROMEPROMFLASH

DIGITALOUTPUT

SUB-SYSTEM

DSP

ANALOG INPUT SUB SYSTEM

CT

PT

SURGESUPPRESSION

SURGESUPPRESSION

ANALOGFILTER

ANALOGFILTER

MUX A / DCONVERTER

MICROPROCESSOR

MICROPROCESSORS Vs MICRO CONTROLERS

CONTROL

CONTROL

Accumulator

Arithmetic LogicUnit

Data Register

Address Register

Data Register

Arithmetic Logic Unit

Address Register

Accumulator

I/OROMRAM

EPROM

TimersCounters

UART

Microprocessor Micro controller

RELAY HARDWARE

NORMALLY 400KV RELAYS SUPPLIED WITH FOLLOWING CONFIGUARATION/HARDWARE

1. MIN 4Nos MAX 8Nos COMMAND/TRIP OUTPUTS 2. MIN 24Nos SIGNAL OUTPUTS3. MIN 14 LED INDICATIONS4. MIN 24 BINARY INPUTS

PCMODEM

IRIG-BRE/CC

16 / 32 BIT

SELF DIAGNOSTICS - TECHNIQUES USED

RAM Checked by computing a checksum of memory contents and comparing it against a stored factory value.

RAM Checked by periodically writing a specific data and reading back the memory contents

A / D Checked by inputing a known value of + / - voltage.Any off set at a given time, is software corrected.

SETTINGS Checked by checksums or CRC values can be stored and compared. Often, 2 or 3 copies of settings are stored and compared.

POWER Checked by monitoring power supply voltage values SUPPLY from A / D converter.

TYPES OF SIGNALS REQUIRED FOR PROPER PROTECTION

Current, Voltage and Distance Relays :Require fundamental frequency component signals. All other signals will interfere with protection process.

Harmonic Restraint Relays :Require both the fundamental & the Harmonic components , each value separately, for decision making process.

4 ND GENERATION1ST DEVELOPMENT:SOFTWARE DEVELOPMENT IS APPLICATION BASED RELAYS i.e EACH PROTECTION FUNCTION HAVING SEPARATE SOFTWARE & HARDWARE.

Example:1. LINE PROTECTION,2. TRANSFORMER PROTECTION,3. BUSBAR PROTECTION, 4. GENERATOR PROTECTION5. MOTOR PROTECTION6. REACTOR PROTECTION7. CAPACITOR PROTECTION

4 ND GENERATION2ND DEVELOPMENT:SOFTWARE DEVELOPMENT IS SOME GROUP BASED RELAYS i.e SOME PROTECTION FUNCTIONS ARE TAKEN IN TO ONE FLATFORM AND PROVIDED COMMON SOFTWARE.FROM THIS INBUILT FACILITY OF EVENT RECORDER AND DISTURBANCE RECORDER IS DEVELOPED.

Example:ABB: 1. REX 5xx SERIES FLATFORM

2. REX 316 SERIES FLATFORM3. REX 670 SERIES FLATFORM4. RED 500 SERIES FLATFORM5. RED 600 SERIES FLATFORM

4 ND GENERATION3RD DEVELOPMENT:UNIVERSAL SOFTWARE FOR ALL TYPES OF RELAYS FOR PARTICULAR MANUFACTURER. i.e. ONE SOFTWARE ONE MANUFACTURER.

Example:1. SIEMENS: SIPROTEC SERIES – DIGSI2. GE MULTILIN: ENERVISTA3. AREVA : MICOM S1

4 ND GENERATION4TH DEVELOPMENT:UNIVERSAL HARDWARE FOR ALL TYPES OF RELAYS FOR PARTICULAR MANUFACTURER. ONE HARDWARE FOR ONE MANUFACTURER. BUT IT IS MODULAR DESIGN. RELAY IS COMMON HARDWARE BASED ON PROTECTION FUNCTION, PARTICULAR CARD IS ADDED.

Example:1. GE MULTILIN: UR SERIES & SR SERIES

4 ND GENERATION5TH DEVELOPMENT:EACH MANUFACTURER ADOPTING THEIR PROPERITIERY BASED PROTOCOL FOR COMMUNICATION, INTERFACING, NETWORKING AND AUTOMATION. SOME UTILTIES ARE REQUESTED MANUFACTURERS TO SUIT THEIR ADOPTED PROTOCOL. Example:1. UCA – Utility communication architecture2. LON3. SPA4. PROFIBUS5. MODBUS6. DNP7. FIELDBUS8. MVB9. IEC 60870

4 ND GENERATION6TH DEVELOPMENT:BASED ON THE EXPERIENCE WITH DIFFERENT PROTOCOLS, NEED FOR UNIFORMITY AND KNOW –HOW FOR GLOBAL CONSIDERATIONONE WORLDONE TECHNOLOGYONE STANDARDA UNIVERSAL PROTOCOL FOR COMMUNICATION, INTERFACING AND NETWORKING IS DEVELOPED. ALL MANUFACTURERS ARE FORM A GROUP AND PROTOCOLS ARE STANDARDIZED. ANY RELAY CAN BE COMMUNICATED FOR COMMON COMMUNICATION PROTOCOL, i.e INTEROPERATABULITY. THIS IS SPECIAL FOR AUTOMATION OF STATIONS.Example:1. IEC 61850

BENIFITS OF UNIVERSAL PROTOCOL

Innovation & Expansionfirm rules for the description of new

data- objects and functionsInteroperability is maintained

Efficient maintenancerobust data modellingself-descriptive equipment automation-configuration in XML

Separation from Application & Communication

data and application stay secure independent from communication

systemsunconstrained further development of

the technology

Quicker project executioncomprehensive data modelclear, standardised project-

and equipment descriptionConfiguration of substation in XML

ETHERNET & TCP/IPAdopted worldwide Scalable technologyCommon use of infrastructure

One Protocol

for all the needs in the substationflexible configuration

no gateways required

INTEROPERATABULITY WITH ABB, AREVA & SIEMENS

TECHNOLOGY COMPARISION

Freely ConfigurableFixedFixedContacts &Assignments

Analogue to Digital Conversion, Numerical Algorithms, Techniques, Evaluation Trip Criteria

Level Detectors Comparison with Reference Value in Analogue Comparators

Electrical Quantities converted into Mechanical Force & Torque

Measuring Method

CountersStatic TimersMechanical Clock works, Dashpot

Timing Function

Microprocessors, Digital ICs, Digital Signal Processors

Discrete R L C, Transistors, Analogue ICs, Comparators

Induction Discs, Electromagnets, Induction cups etc

Measuring Elements & Hardware

Trip Relays are Inbuilt

Additional Trip Relay Required

Additional Trip Relay Required

Trip Command

LEDs & LCD Display

LEDsFlags, TargetsVisual Indication

NUMERICALSTATICELECTROMECHANICALSUBJECT


PossibleNot PossibleNot PossibleMultiple Characteristics

PossibleNot PossibleNot PossibleMultiple Integrated Protection func

Not required as settings are stored permanently in Memory in Digital Format

Required as settings drift due to ageing

Frequently Required as settings drift due to ageing

Calibration

Most CompactModular, CompactBulkyHardware SizeHuman Machine Interface, Softwares

Thumb Wheel, Potentiometers, DIP Switches

Plug Setting, Dial Setting

Parameter Setting

AvailableNot PossibleNot PossibleSequence of Events

AvailablePartially AvailableNot AvailableSelf Supervision

Available & Freely Configurable

Not AvailableNot AvailableBinary Input & Output



Extension and New development Possible and Open Architecture

FixedFixedSolution

Stored In MemoryNot PossibleNot possibleFault History

Protection Control & Monitoring

Protection & Monitoring

Only ProtectionProtection Control & Monitoring

PossibleNot PossibleNot PossibleService value Indication

InbuiltExternal HardwareExternal HardwareDisturbance Recording

WideModerateLimitedRange of Settings

LowerLower Than Electromechanical & Moderate

HigherBurden on CTs, PTs & CVTs

AvailableNot PossibleNot PossibleCommunication facility


Relay ANSI Numbers (IEEE C37.2)

Carrier or Pilot wire Receive Relay85Inst Over-Current Relay50Operating Mechanism84M/C or T/F Thermal Relay49

Trip circuit supervision Relay95Over-Voltage Relay59Over-Flux Relay99Voltage / Current balance Relay60

Isolator or Disconnector89Exciter or DC Generator Relay53

Voltage Directional Relay91Power Factor Relay55

Voltage or Directional Power Relay92Field Application Relay56

Differential Relay87AC Circuit Breaker52Lockout/Tripping Relay86AC IDMT Over-Current Relay51

Automatic selective control or Transfer Relay83Negative phase sequence Relay46

AC Auto Reclosure Relay79Under Current / Power Relay37Frequency Relay81Field failure (loss of excitation)40

Density Switch or Sensor61Time delay relay2Pressure Switch63Interlocking relay3

Phase Angle measuring or out of step Relay78Directional Power Relay32DC Over-Current Relay76Annunciation relay30

Directional Over Current Relay67Volts per Hertz Relay24Blocking/Locking Relay68Synchronism Check Relay25

Restricted Earth Fault Relay64Distance Relay21

Alarm Relay74Isolating Contactor29DC Circuit Breaker72Under Voltage Relay27

DEVICENUMBERDEVICENUMBER

17648889 Introduction to Power System Protection Relays

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Transcript of 17648889 Introduction to Power System Protection Relays