SOUTHERN REGIONAL LOAD DESPATCH CENTERPOWERGRID, BANGALORE

Data Acquisition &

CommunicationAbhimanyu Gartia

Chief Manager,SCADA-IT

SRLDC

Instrumentation For SCADAInstrumentation For SCADA

TransducersTransducers RTURTU Current TransformerCurrent Transformer Capacitor Voltage TransformerCapacitor Voltage Transformer

TRANSDUCERTRANSDUCER

Device converts one form of energy to another form.Device converts one form of energy to another form. Energy form viz. electrical, mechanical, chemical etc.Energy form viz. electrical, mechanical, chemical etc. Transforms High level to Low levelTransforms High level to Low level Input – Hundreds of voltInput – Hundreds of volt Output – Few milliamperesOutput – Few milliamperes Measures field parameters like voltage, frequency, Measures field parameters like voltage, frequency,

current, 3 phase bi directional active & reactive power current, 3 phase bi directional active & reactive power and transformer tap positionand transformer tap position

Accuracy : +/- 0.2% class for frequency transducers Accuracy : +/- 0.2% class for frequency transducers and +/- 0.5% class for other transducersand +/- 0.5% class for other transducers

TRANSDUCERTRANSDUCER TYPICAL RATINGTYPICAL RATING TransducerTransducer Input Input OutputOutput Voltage 0-110 V 0-10 mAVoltage 0-110 V 0-10 mA Current 0-1 Amp 0-10 mACurrent 0-1 Amp 0-10 mA 0-5 Amp0-5 Amp Frequency 4-20 mAFrequency 4-20 mA MW 4-12-20mAMW 4-12-20mA MVAR 4-12-20mAMVAR 4-12-20mA

RRemote emote TTerminal erminal UUnitnit

The RTU performs the data acquisition and The RTU performs the data acquisition and supervisory control over the substation for the SCADA supervisory control over the substation for the SCADA system.system.

As a minimum, the RTU collects, processes and As a minimum, the RTU collects, processes and transmits the data from the substation to the control-transmits the data from the substation to the control-centers.centers.

The following data are generally acquired from the The following data are generally acquired from the sub-station:-sub-station:-

AnalogAnalog- Power, Reactive Power, Voltage, - Power, Reactive Power, Voltage, Frequency, Current.Frequency, Current.

DigitaDigitall- Circuit Breaker Status, Isolator Status,SOEs- Circuit Breaker Status, Isolator Status,SOEs The RTU also receives and processes digital and The RTU also receives and processes digital and

analog commands. analog commands.

RTU: MAIN FUNCTIONSRTU: MAIN FUNCTIONS

SCADASCADA Local ControlLocal Control Data LoggingData Logging Process ControlProcess Control

HARDWARE CONNECTIVITY DIAGRAM FOR SCADA HARDWARE CONNECTIVITY DIAGRAM FOR SCADA AT SUBSTATION / GEN.STATIONAT SUBSTATION / GEN.STATION

MAINCPU

BOARDPSU

COMMNBOARD

ANALOG

I / P

DIGTAL

I / P

CONTROLO/P

TERMINALBLOCK

TERMINAL BLOCK

TERMINALBLOCK

REMOTE TERMINAL UNIT

TRANSDUCER O/P TERMINAL

MVAR VOLTMW

TRANSDUCER I/P TERMINAL P TSEC

110VAC

CT SEC1 AMPS

FROM

SWITCHYARD-FIELD

EVENT LOGGERPANEL

DRIVER

RELAY

TRANSDUCER PANEL

RS232 PORT

SCADA HARDWARE CONNECTIVITY WITH SCADA HARDWARE CONNECTIVITY WITH COMMUNICATION SYSTEM(PLCC) AT SUB-STN/GEN STCOMMUNICATION SYSTEM(PLCC) AT SUB-STN/GEN ST

RTU

NSK5

modem

PLCC T x / R xSPEECH / DATA

PANEL

RS 232 CONNECTIVITY

PLCCINDOOR EQUIMENT

TRANSDUCERSTRANSDUCERS

CLASSIFICATIONCLASSIFICATION SELF POWERED/AUXILARY POWEREDSELF POWERED/AUXILARY POWERED

INPUTINPUT VOLTAGE/CURRENT/POWER/POSITIONVOLTAGE/CURRENT/POWER/POSITION

OUTPUTOUTPUT 0-10mA, 4-20mA, 0-5mA 0-5v,0-10v0-10mA, 4-20mA, 0-5mA 0-5v,0-10v

OUTPUT IMPEDANCEOUTPUT IMPEDANCE 500500ΩΩ,1000,1000ΩΩ,2000,2000ΩΩ

ACCURACYACCURACY 0.2 CLASS, 0.5 CLASS, CLASS 2 AND ABOVE0.2 CLASS, 0.5 CLASS, CLASS 2 AND ABOVE

A/D CONVERSION AT RTU LEVELA/D CONVERSION AT RTU LEVEL(16 BIT ADC).(16 BIT ADC).

FOR MW / MVAR TRANSDUCER:INPUT: PT SEC PHASE TO PHASE : 110VAC CT SEC TWO PHASE CURRENT (R & B): 1 AMPS.

OUTPUT : 4 – 20mA(TRANSDUCER OUTPUT)

IN ADC:

AT 4mA = 6553 CountAT 20mA = 32767 Count12mA IS THE CENTRE POINT.(+/- 0.1% IS THE ACCEPTABLE RANGE OF ERROR ON FULL SCALE)( Ref Calculation Sheet for all type of Measurand)

TRANSDUCERSTRANSDUCERS Measures field parameters like voltage, frequency, Measures field parameters like voltage, frequency,

current, 3 phase bi directional active & reactive current, 3 phase bi directional active & reactive power and transformer tap position.power and transformer tap position.

RatingRating Vol: 110/115 volts phase to phaseVol: 110/115 volts phase to phase

Current : 1 ACurrent : 1 AFrequency: 45-55 HzFrequency: 45-55 Hz

Output : 4 – 20 ma / 500 ohmsOutput : 4 – 20 ma / 500 ohms External power supplyExternal power supply IEC 688IEC 688 Accuracy : +/- 0.2% class for frequency transducers Accuracy : +/- 0.2% class for frequency transducers

and +/- 0.5% class for other transducersand +/- 0.5% class for other transducers

SALIENT FEATURES OF ULDC RTUSALIENT FEATURES OF ULDC RTU A small rugged computerA small rugged computer CPU, volatile & non-volatile memory, power CPU, volatile & non-volatile memory, power

supply module, I/O modulesupply module, I/O module Communication ports & maintenance portsCommunication ports & maintenance ports Allows the central SCADA master to communicate Allows the central SCADA master to communicate

with the field deviceswith the field devices Acquires the data from the field Acquires the data from the field

devices/equipment and transfers the data to the devices/equipment and transfers the data to the SCADA systemSCADA system

Distributed Processing Technology Distributed Processing Technology Main processor is 32-Bit 16Mhz and sub modules Main processor is 32-Bit 16Mhz and sub modules

are 8-bit.are 8-bit. Real time clockReal time clock Access via PC-Based Configuration.Access via PC-Based Configuration. Password Protected.Password Protected. Database configured via a PC and can be Database configured via a PC and can be

downloadeddownloaded

SALIENT FEATURES OF ULDC RTUSALIENT FEATURES OF ULDC RTU Switch mode converter power supply module which Switch mode converter power supply module which

provides power for mother board, VME cards, I/O provides power for mother board, VME cards, I/O modules and peripherals. Input voltage – 241 V AC, modules and peripherals. Input voltage – 241 V AC, 50 Hz. Outpit voltage +/-5V DC, +/- 12 V DC, +/- 24 50 Hz. Outpit voltage +/-5V DC, +/- 12 V DC, +/- 24 V DCV DC

32 Analog inputs per module ,15 bit resolution .32 Analog inputs per module ,15 bit resolution . Conversion rate 660 ns for all 32 inputs.Conversion rate 660 ns for all 32 inputs. 64 status inputs per status module,1ms scan time 64 status inputs per status module,1ms scan time

for 64 inputs,1ms SOE resolution. A simple status for 64 inputs,1ms SOE resolution. A simple status input/SOE input/accumulator input can be input/SOE input/accumulator input can be connected. LED indicators for each input. Contact connected. LED indicators for each input. Contact wetting voltage supplied by power supply module.wetting voltage supplied by power supply module.

32 control output per control module. Two master 32 control output per control module. Two master relays for each output. One for close and one for trip.relays for each output. One for close and one for trip.

Through the maintenance port, we can download the Through the maintenance port, we can download the database, view data and Communications specific to database, view data and Communications specific to each peripheral board and trouble shoot . each peripheral board and trouble shoot .

Advanced diagnostic capabilitiesAdvanced diagnostic capabilities Time synchronisation of RTU done at every 1 minute.Time synchronisation of RTU done at every 1 minute.

Scan CyclesScan Cycles All the analog data are scanned every All the analog data are scanned every

10/12 seconds10/12 seconds Status information are reported by Status information are reported by

exceptionexception All status information are scanned for All status information are scanned for

integrity check every 10 minutesintegrity check every 10 minutes The SOE datas are time stamped at 1 ms The SOE datas are time stamped at 1 ms

resolution resolution Time synchronisation is done every 10 Time synchronisation is done every 10

minutesminutes

Current TransformerCurrent Transformer

A current transformer is a measurement A current transformer is a measurement device designed to provide a current in device designed to provide a current in its secondary coil proportional to the its secondary coil proportional to the current flowing in its primary .current flowing in its primary .

The current transformer isolates The current transformer isolates measurement and control circuitry from measurement and control circuitry from the high voltages typically present on the high voltages typically present on the circuit being measured .the circuit being measured .

Common secondary are 1 or 5 amperes. Common secondary are 1 or 5 amperes. For example, a 4000:5 CT would provide For example, a 4000:5 CT would provide an output current of 5 amperes when an output current of 5 amperes when the primary was passing 4000 amperes .the primary was passing 4000 amperes .

Capacitor Voltage Capacitor Voltage TransformerTransformer

Capacitor Voltage transformers (CVTs) Capacitor Voltage transformers (CVTs) are used for metering and protection in are used for metering and protection in high-voltage circuits. They are designed high-voltage circuits. They are designed to present negligible load to the supply to present negligible load to the supply being measured and to have a precise being measured and to have a precise voltage ratio to accurately step down voltage ratio to accurately step down high voltages so that metering and high voltages so that metering and protective relay equipment can be protective relay equipment can be operated at a lower potential. operated at a lower potential.

Basic Function Of the CVTBasic Function Of the CVT Where CHF is the equivalent Where CHF is the equivalent

rated capacitance for carrier rated capacitance for carrier communicationcommunication

* C1 : High Voltage * C1 : High Voltage capacitorcapacitor

* C2 : Intermediate Voltage * C2 : Intermediate Voltage CapacitorCapacitor * C1 / C2 ratio is such that * C1 / C2 ratio is such that

the required intermediate the required intermediate voltage can be achievedvoltage can be achieved

L : Inductance of the choke L : Inductance of the choke which is designed to which is designed to

* Prevent carrier signals * Prevent carrier signals from flowing into the from flowing into the transformer circuit.transformer circuit.

* Resonate with the * Resonate with the capacitor unit at 50 Hz which is capacitor unit at 50 Hz which is the rated frequency.the rated frequency.

D : Damping burden which is D : Damping burden which is provided across one of the provided across one of the secondary windings to prevent secondary windings to prevent terroresonance oscillations.terroresonance oscillations.

Tr : Transformer designed to Tr : Transformer designed to provide the required output provide the required output voltage at the desired burdenvoltage at the desired burden

Metering

Protection

D

1a

1n

2a

2n

HV

C1

C2

TrL

CHF

COMMUNICATION REQUIREMENTS FOR

SCADA

COMMUNICATION COMMUNICATION REQUIREMENTS FOR SCADAREQUIREMENTS FOR SCADA

Communication media should have:Communication media should have: * High Reliability* High Reliability * High Availability* High Availability * Rapid Response* Rapid Response * Transparency* Transparency * Economy* Economy * Flexibility* Flexibility * Maintainability* Maintainability

Modes of CommunicationModes of Communication

PLCCPLCC Leased Telephone circuitsLeased Telephone circuits Microwave CommunicationMicrowave Communication Fibre Optics CommunicationFibre Optics Communication Satellite CommunicationSatellite Communication

PLCCPLCC High voltage lines themselves are used as High voltage lines themselves are used as

communication links.communication links. Carrier Frequency: 50-300 KHz.Carrier Frequency: 50-300 KHz. 3 channels are used generally:3 channels are used generally: Main-Channel ->Main-Channel -> speech channel – 300 Hz to 2000 Hzspeech channel – 300 Hz to 2000 Hz Telemetring- 2000 Hz to 3400 HzTelemetring- 2000 Hz to 3400 Hz

Protection-Channel-I ->Protection-Channel-I -> speech channel – 300 Hz to 2000 Hzspeech channel – 300 Hz to 2000 Hz Teleprotection- 2000 Hz to 3400 HzTeleprotection- 2000 Hz to 3400 Hz

Protection-Channel-II (Backup-Protection)->Protection-Channel-II (Backup-Protection)-> speech channel – 300 Hz to 2000 Hzspeech channel – 300 Hz to 2000 Hz Teleprotection- 2000 Hz to 3400 HzTeleprotection- 2000 Hz to 3400 Hz

PLCCPLCCAdvantages:Advantages:1.1. High reliabilityHigh reliability2.2. All channels are available for dedicated use by All channels are available for dedicated use by

power-utility alonepower-utility aloneDisadvantages:Disadvantages:1.1. Cost of insulating communication equipment is Cost of insulating communication equipment is

highhigh2.2. High noise level due to CoronaHigh noise level due to Corona3.3. High speed data-transfer not possible because High speed data-transfer not possible because

of of Bandwidth limitations.Bandwidth limitations.

Applications of PLCCApplications of PLCC Voice CommunicationVoice Communication Fascimile TransmissionFascimile Transmission Tele-ProtectionTele-Protection Tele-MeteringTele-Metering

Types of CouplingsTypes of Couplings

3 coupling schemes to couple voice, 3 coupling schemes to couple voice, fax, tele-protection and tele-metering fax, tele-protection and tele-metering to the high-voltage transmission line:to the high-voltage transmission line:

Phase-to-Ground CouplingPhase-to-Ground Coupling

Phase-to-Phase CouplingPhase-to-Phase Coupling

Inter-Line CouplingInter-Line Coupling

STATION-B

PLCC PANELS

STATION-A

LMU

ESLADC

CC

WT

PLCC PANELS

ESLADC

CC

WT

PHASE-TO-GROUND COUPLING

ES=Earth Switch DC=Drainage Coil WT=Wave Trap

LA=Lightening Arrester LMU=Line Matching Unit CC=Coupling capacitor

STATION-B

PLCC PANELS

STATION-A

LMU

ESLADC

CC

WT

PLCC PANELS

ESLADC

CC

WT

PHASE-TO-PHASE COUPLING

ES=Earth Switch DC=Drainage Coil WT=Wave Trap

LA=Lightening Arrester LMU=Line Matching Unit CC=Coupling capacitor

BT=Balancing Transformer

WT

LMU

BT BT

LMU LMU

CC

WT

CC

STATION-B

PLCC PANELS

STATION-A

LMU

ESLADC

CC

WT

PLCC PANELS

ESLADC

CC

WT

INTER-LINE COUPLING

ES=Earth Switch DC=Drainage Coil WT=Wave Trap

LA=Lightening Arrester LMU=Line Matching Unit CC=Coupling capacitor BT=Balancing Transformer

LMU

BT BT

LMU LMU

CCCC

Microwave CommunicationMicrowave Communication

Line-of-sight communicationLine-of-sight communication Requires repeaters at 50-60 kms. IntervalsRequires repeaters at 50-60 kms. Intervals Provides sufficient bandwidth to meet the needs of Provides sufficient bandwidth to meet the needs of

power utilitypower utility Higher availability than PLCC, availablity not affected Higher availability than PLCC, availablity not affected

by maintenance or faults on the power linesby maintenance or faults on the power lines Suffers from multipath-fading effectSuffers from multipath-fading effect In India, WPC (wireless planning & co-ordination) In India, WPC (wireless planning & co-ordination)

wing has assigned 2.3-2.5 GHz and 2.8-5 GHz bands wing has assigned 2.3-2.5 GHz and 2.8-5 GHz bands to power sector usage.to power sector usage.

Digital Microwave Systems

Leased Telephone CircuitsLeased Telephone Circuits•Simple solution, no need to develop own dedicated communication facility by power utility

•Availability of this mode of communication at remotely located substations is the deciding factor

Fiber-Optic CommunicationFiber-Optic Communication Fiber-optic communication is a method of transmitting Fiber-optic communication is a method of transmitting

information from one place to another by sending light through information from one place to another by sending light through an optical fiber. The light forms an electromagnetic carrier wave an optical fiber. The light forms an electromagnetic carrier wave that is modulated to carry informationthat is modulated to carry information

• The process of communicating using fiber-optics involves the following basic steps: Creating the optical signal using a transmitter Relaying the signal along the fiber, ensuring that the signal does not become too distorted or weak Receiving the optical signal and converting it into an electrical signal

Analog/DigitalInterface

Voltage toCurrent

converter

LightSource

Source toFiber

Interface

Fiber toLight

Detector Interface

LightDetector

Current toVoltage

converter

Analog/DigitalInterface

OUTPUT

INPUT

Optical Fiber

Fiber Optic CommunicationFiber Optic Communication Advantages:Advantages: The ability to carry much more information and deliver it with greater The ability to carry much more information and deliver it with greater

fidelity than either copper wire or coaxial cable.fidelity than either copper wire or coaxial cable.

Fiber optic cable can support much higher data rates, and at greater Fiber optic cable can support much higher data rates, and at greater

distancesdistances The fiber is totally immune to virtually all kinds of interference, The fiber is totally immune to virtually all kinds of interference,

including lightning, and will not conduct electricity. It can therefore including lightning, and will not conduct electricity. It can therefore come in direct contact with high voltage electrical equipment and come in direct contact with high voltage electrical equipment and power lines. power lines.

POWERGRID POWERGRID uses overhead fiber optic communication:uses overhead fiber optic communication:

OPGWOPGW (optical ground wire cable) (optical ground wire cable)

ADSSADSS (all dielectric self supporting cable) (all dielectric self supporting cable)

WRAP AROUNDWRAP AROUND

Fibre Optic Systems

OPGW

FODP OLTE

ADD DROP MUX2 MB/S

MICROWAVE RADIO TERMINAL

2 MB/S

INTEGRATION OF DIGITAL & ANALOG NETWORKS

PLCC

VOICE CARD

DATA CARD

OPGWOPGW

OPGW (optical ground wire) OPGW (optical ground wire) replaces shield wiresreplaces shield wires

• • Provides lightning protectionProvides lightning protection• • Provides communicationProvides communication• • Lightning short circuit damageLightning short circuit damage• • Installation requires long term Installation requires long term

outageoutage• • ExpensiveExpensive• • Superior performanceSuperior performance

ADSS F.OADSS F.O

ADSS (all dielectric self supporting) whichADSS (all dielectric self supporting) which

is mounted at various locations, typically 3is mounted at various locations, typically 3

to 10 meters below the phase conductorsto 10 meters below the phase conductors.. ADSS costs less than OPGWADSS costs less than OPGW Higher fiber count than Wrap type.Higher fiber count than Wrap type. Can be installed on towers not designed for Can be installed on towers not designed for

shield wires.shield wires. Suitable for hot line installationSuitable for hot line installation

WRAP AROUND F.OWRAP AROUND F.O

Wrap-type which is wound around Wrap-type which is wound around shield wires and, in some shield wires and, in some instances, around energized instances, around energized conductorsconductors

Hot-line installation is difficultHot-line installation is difficult Cost more than ADSS, but less Cost more than ADSS, but less

than OPGWthan OPGW Need a shield wireNeed a shield wire No operation problem is observedNo operation problem is observed

OPGW

WRAP

ADSS

OVERHEAD CABLES FOR OVERHEAD CABLES FOR POWER UTILITIESPOWER UTILITIES

OPGW ADSS WRAP AROUND

AL STRANDAL COATED STEEL STRAND

AL TUBE

XLPE SHEATH

POLYESTER TAPE

MOISTURE BLOCKING COMPOUND

AERIAL OPTICAL FIBRE CABLES

FIBRESTRENGTH MEMBERS

LOOSE TUBE

AD\AS\RKG\JP\FIBCROSS

FIBRE OPTIC CABLE INSTALLATION

OPGW

WRAP AROUND

ADSS

AD\AS\RKG\JP\FIBINST

SATELLITE COMMUNICATIONSATELLITE COMMUNICATION

A geostationary satellite is A geostationary satellite is used as an active used as an active repeater.repeater.

Modulated signals are Modulated signals are send from earth VSATs in send from earth VSATs in 6 GHz band to the 6 GHz band to the satellite.satellite.

Signals are beamed back Signals are beamed back to earth in 4 GHz band.to earth in 4 GHz band.

Roundtime propagation Roundtime propagation delay of 540ms existsdelay of 540ms exists

Communication is Communication is interrupted during interrupted during eclipses.eclipses.

WHAT IS SCADAWHAT IS SCADA

SSupervisory upervisory CControl ontrol AAnd nd DData ata

AAcquisition is the system which enables cquisition is the system which enables us to us to

““supervise, control, optimise and manage supervise, control, optimise and manage the Power Systems in an efficient manner the Power Systems in an efficient manner to provide stable, secure and reliable to provide stable, secure and reliable power to the end consumer”.power to the end consumer”.

FUNCTIONS OF SCADAFUNCTIONS OF SCADA

DATA ACQUISITIONDATA ACQUISITION PROCESSING OF ACQUIRED DATA.PROCESSING OF ACQUIRED DATA. LIMIT / STATUS MONITORING & ALARMING.LIMIT / STATUS MONITORING & ALARMING. NETWORK STATUS PROCESSOR.NETWORK STATUS PROCESSOR. SEQUENCE OF EVENT RECORDING.SEQUENCE OF EVENT RECORDING. INFORMATION STORAGE & RETRIEVAL.INFORMATION STORAGE & RETRIEVAL. DATA EXCHANGE DATA EXCHANGE SUPERVISORY CONTROL.SUPERVISORY CONTROL.

SCOPE FOR DATA-ACQUISITION SCOPE FOR DATA-ACQUISITION UNDER ULDC SCHEMES in INDIAUNDER ULDC SCHEMES in INDIA

All generating stations of 50MW or All generating stations of 50MW or

above(10 MW or above in case of above(10 MW or above in case of NER)NER)All 400 KV Sub-Stations.All 400 KV Sub-Stations.All 220 KV Sub-Stations.All 220 KV Sub-Stations.All 132 KV Sub-Stations operated All 132 KV Sub-Stations operated where where

Inter-State lines are located.Inter-State lines are located.Important 66 KV Sub-Stations (NER Important 66 KV Sub-Stations (NER only).only).

Andhra Pradesh

Karnataka

Kerala

Tamilnadu

UT of Pondy

Vijayawada

Warangal

HYDERABADGhanapur

Chinkampalli

CHENNAI

Pondy

Madurai

Kannur-B

KALAMASSERY

Vydyuthi Bhavanam

Erode

MW LinkFO LinkState owneed Link

Sub-LDC

SLDC

RCLDC

LingasugurDavangere

Bangalore

Information Flow to Control CentresInformation Flow to Control Centres

Satellite

Ramagundam

Lingasugur

Sembatti

Madurai 400

Trichy 400

Paramakudi Samayapuram Madurai North

Kodayar PH2

MaduraiSub LDC

Karaikudi

Tanjore 230

S R PudurPariyar PH

Theni Kayathar E

Sathur

TTPS

Podukotta C

Echengodu

Adanakottai

Peramballur

Kovilvenni

Pugalur

Thiruvarur

Tuticorin Auto

Trichy 230

Chennai Sub-LDC

(NLC TS-I)

Erode Sub-LDC(Erode)

Wideband Channel Routing for Madurai Sub-LDC

OrthonaduSivagangai

Existing RTU – 9 nos.

Existing RTU integrated

New RTUs – 13 nos.

PLCC Link

MW Link

ChalakudyT. NorthKozhikode -BKannur-B

Kalamassery

PallomKayamkulamKundraParipallyTrivendrumNorth

VidyuthiBhavanam

RSCC,Bangalore (Udumalpet)

Wideband Routing from Sub-LDC to SLDC,(Kalamassery)COMMUNICATION NETWORK FOR KERALA

MW Link

FO Link