Sessi 2 RTU TNB

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Transcript of Sessi 2 RTU TNB

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KURSUS KOMPETENSITELEKONROL

Versi 1-05

SESSI 2

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Kandungan Sessi

• Bincang mengenai: - – Rekabentuk RTU – Spesifikasi RTU di dalam TNB

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Role of RTU

• Collect data from the plant• Process and execute control commands fromthe Master Station

• Additional Roles:- – Data Concentrator

• Collects data from IEDs, slave RTUs, etc

– PLC• As PID Controller

• Runs Logic Programs

– Disturbance Recorder – Local Control

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Rekabentuk RTU• Typically grouped into either:-

– Single Board RTU – Modular RTU

• Modular RTU

– Single Processor• Talus RTU

– Master Processor with Inteliigent I/O• Foxboro C50

• GE D20 – Networked RTUs

• Microsol• PDSB Viscon2

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Role of RTU

• Collect data from the plant• Process and execute control commands

from the Master Station

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RTU – MAJORINTERFACES

RTU

CONTACT INPUTS

ANALOG INPUTS

CONTACT OUTPUTS

ANALOG OUTPUTS

COMMUNICATIONCHANNEL(TO MASTER)

MAN MACHINE INTERFACE

PRIMARY POWER

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RTU – MAJORCOMPONENTS

COMMUNICATIONINTERFACE

COMMONLOGIC

DIGITAL INPUTLOGIC & TERM.

ANALOG INPUTLOGIC & TERM.

DIGITAL OUTPUTLOGIC & TERM.

ANALOG OUTPUTLOGIC & TERM.

POWER SUPPLY

RTU

Indication, pulse counterdigital measured value

Analog measuredvalue

command Analogoutputs

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RTU POWER SUPPLY

• Power needed for:- – the operation of the RTU itself, – isolated power for the “wetting” of contact inputs, – the operation of the coils of heavy duty interposing

relays of the control output points (Refer ControlOutput Subsystem Requirements)

– Communication equipment such as modems.• In TNB, RTUs have been powered by:-

– AC with internal RTU Chargers that are batterybacked

– 48Vdc supplied by dedicated RTU Battery Charger – 48Vdc supplied by Telecommunications Battery

Charger

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RTU POWER SUPPLY• Because of maintenance issues and cost-

effectiveness, new policy is to use station DC supplyto power the RTU.• Two types of DC Supply systems in TNB substations

that are equipped with circuit breakers:- – 110V DC Center-Tap Earthed System, typically found in

substations with voltage level of 33kV and above, – 30V DC System (floating earth), typically found in substationswith only 11kV circuit breakers.

• RTU power supply module shall be able to operatefrom an input substation DC power supply with atolerance of +20% and -15% of nominal input voltageand maintain full normal operation over the inputsupply range.

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RTU CLOCK• RTU requires clock for:-

– Time-tagging of events such as SOE – Synchronizing other sub-ordinate devices such as IEDs etc.

• The RTU shall be equipped with a real time clock withfull calendar (including leap year support).

• The RTU shall maintain date and time duringdeenergisation of up to 72 hours such that upon start-up the latest time is used.

• The minimum discernable change in the timegenerated by the RTU Clock is defined as the RTUClock Resolution. The RTU clock resolution shall be

1 millisecond (IEC 60870-4 Table 7 Class TR4).• The clocks shall have an accuracy of 2 ppm and shall

not drift more than 7.2 msec per hour.

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RTU CLOCK• Why 2ppm?

– 2 x 10-6 x 60 seconds x 60 minutes = 7.2ms/hr – For SOE, we require time between two substations to

be within 10ms of each other. – Optimal time-synchronization frequency from Master

Station is once every hour• Why battery-backed up to three days?

– Best to have the RTU start-up with the present dateand time

– Not dependant on initialization and time-sync frommaster to start operations, i.e. comms to be available

– Can start logging events (event-logging function)

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DIGITAL INPUT MODULE• The Digital Input Subsystem shall be made up of

modules and termination assemblies to monitorthe state of devices and alarms through thesensing of the state of contacts. These contactsfrom the plant equipment are voltage free contacts

• Plant provides voltage free contacts. RTU willprovide the sensing voltage. TNB does not specifysensing voltage

• Sensing voltage can be internal (from RTU‟s PSU)or external (eg from station DC, 110Vdc)

• Two methods for sensing digital inputs:- – Provide sensing voltage across the digital input point and

its common – Provide a make contact across the digital input point and

its common

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DIGITAL INPUT MODULE

S

C

Vsense

Eg:

Contact Closed -> V sense = 48Vdc -> Logic 1

Contact Open -> V sense = 0Vdc -> Logic 0

Field Contact

Digital Input Module

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DIGITAL INPUT MODULE

S

C

Eg:Contact Close -> Logic 1

Contact Open -> Logic 0

Field Contact

Digital Input Module

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DIGITAL INPUT MODULE – The RTU must be able to detect and process

any event of at least 5ms in duration. Anyevents with less than 5ms duration shall beregarded as contact bounce or spurious

signals. Minimum Detect Time – The RTU shall have a programmable

debounce filter that can be configured toreject pulses from 5ms to 25 ms in width, in1ms steps. A digital filter is preferred for thisapplication.

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Debounce Filters: Function is to filter contact bounce

Contact debounce period is the amount of time for which the state of adigital input points must be detected in a valid ON or OFF condition,

before it is considered to be in that conditions

Contact Bounce

DebouncePeriod

Change of staterecognised

Final State

InitialState

DIGITAL INPUT MODULE

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DIGITAL INPUT MODULE• Relay Chattering

– The relay chatter filter will have two configurableparameters; the number of changes, Nc and thechatter filter period, Tc , to define its filtering function.If a point changes state more than Nc times within a

period of Tc , the system will mark the point aschattering and disable it so that no further changes ofstate or events will be recorded until the pointrecovers from chattering.

– The relay chatter filter must be able to automatically

restore monitoring of the point when it detects that it isno longer in a chattering state.

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DIGITAL INPUT MODULE• Double Bit Processing

– The transition states are “00” and “11”. Valid states are “01”and “10”.

– When a double-bit point changes state, the detecting systemwaits for a time interval equal to the double-bit processing time.

– If the point changes state to a transition state and then to a finalvalid state during that interval, the digital input subsystem willnot report the transition state.

– If the point fails to reach a valid state at the end of the interval,the subsystem will report the transition state as the final state.

– The double-bit processing time shall be a configurableparameter ranging from 0 to 255 seconds (default 10 seconds).

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DIGITAL INPUT MODULE –

Double Bit Processingt0 10 Closed

t1 00 Travel

t2 01 Open

tC

tC – Change TimetDBP – Double Bit Processing Time

Case TimeReported

Events Reported

t2-t1 > tDBP t1 + t DBP

t2

CB Travel at <t 1>CB Open at <t 2>

t2-t1 < tDBP t2 CB Open at <t 2>

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DIGITAL INPUT MODULE – Sequence of Events (SOE)

– It shall be possible to assign any DI data points inthe RTU as an SOE point.

– When a change of state occurs, the event shall be

identified with a point identification number, the typeof event, and the time of occurrence in hours,minutes, second, and milliseconds.

– events that occur when RTU not time sync shall still

be time-tagged but RTU must flag the events aspossibly out of synchronization.

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DIGITAL INPUT MODULE –

Sequence of Events (SOE) – All events must be time-tagged with the timeof occurrence.

– The maximum variation between the timethat the system tags an event and the actualtime the event happens is defined as the“Event Time Tagging Error”. The Event TimeTagging Error should not be more than onemillisecond.

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DIGITAL INPUT MODULE -SOE

– Separat ing Capabi l i ty is the minimum timeby which events must be separated such thatthe sequence of their occurrence can bedetermined correctly. The time separatingcapability shall be 5 milliseconds for eventsoccurring within a substation (IEC 60870-4Table 6 Class SP3).

– SOE Time Resolution is the minimum time bywhich two events must be separated in orderthat the corresponding time tags are different.The Time Resolution shall not exceed onemillisecond.

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DIGITAL INPUT MODULE – SOE

• The RTU shall have a Main SOE buffer located inthe RTU‟s main processor or similar module.• This Main SOE buffer shall contain time-tagged

sequential memory to store SOE events from allthe digital input modules and subsystems within

the RTU.• The RTU shall use this Main SOE buffer to reportSOE data to the Host.

• Event shall be stored in the chronological order inwhich they occur.

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DIGITAL INPUT MODULE – SOE

• This cyclic memory buffer shall be separatefrom all other RTU data buffers.

• When the cyclic buffer becomes full of entriesthat have not been reported to the Host theevent archiving ceases and the RTU notes itis now „losing‟ events. An alarm indicationshall be provided to indicate that the RTUSOE data buffer has overflowed.

• Events that have been reported to the Hostcan be overwritten by new events.

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Counters• Most RTUs use the same digital input module for counters• A dedicated module maybe required if the digital input module

cannot handle the count rate specified• TNB requirements : The maximum input pulse rate will be at least 20

pulses per second. Based on energy meters.• Each pulse counter readings shall be maintained in 32-bit registers.• FREEZE commands generated internally within the RTU at a regular

time intervals. The FREEZE command shall cause the contents ofthe counter register to be copied to a separate freeze register. RTUread the freeze register and transmit counts to the master stationwhen requested without changing the contents of the register.

• RESET commands can also be generated internally within the RTU ata regular time. The RESET command effectively zeroes the counter.

• FREEZE & RESET commands generated internally within the RTU ata regular interval. A reset of the count shall take place once it hasbeen frozen and reported. The time stamp at the time of freeze shallbe recorded.

• User configurable, channel-by-channel basis, range 1 –255 minutes(default 30 minutes).

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BCDs• BCD functionality normally integrated with the

Digital Input Module• The number of BCD digits shall be configurable

from one decade (0…9) to four decade

(0000…9999) without sign. • A settling time shall be configurable for each

BCD input for validating a stable BCD inputindication. The settling time is selectable insteps in the range of 0.1 to 25.5 seconds. Anychange on an input channel shall retrigger thesettling time.

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ANALOG INPUTS• A/D conversion shall be with a minimum resolution of

12 bits, plus the sign bit for bipolar conversion giving anoverall range of – 4096 to +4095.

• Over-range detection shall be provided.• The overall accuracy of the DC Analogue Input Sub-

system, from input terminal to digital value shall bebetter than 0.1% for current inputs and 0.05% forvoltage inputs, of full scale within the specifiedoperating range of the equipment, with less than +/-0.005% per deg. C temperature error.

• For the 4-20mA dc analogue inputs, 4mA willcorrespond to a count of 0; 20mA will correspond to themaximum count, while 0mA will give a correspondingnegative count. For a 12-bit ADC, 4mA will correspondto 0 count, 20mA to 4095 while 0mA will give a readingof – 1024 count.

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ANALOG INPUTS

• Analog Input modules can provideinstantaneous values

• Configurable parameters:- – Deadband/Jitter – Force to Zero – Smoothing Factor

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ANALOG INPUTS – Deadband/Jitter/Threshold

– To prevent noisy input signals fromcontinuously reporting analogue fluctuationswithin the RTU and to the Master Station

– Only values that changes by a value that

exceeds the Deadband will be recorded andreported.

– configurable in the range of 0 to at least 5% offull scale

OG S

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ANALOG INPUTS - Force toZero

– To eliminate noise fluctuations around thezero value,

– The RTU shall report a zero value for anyreadings within zero and the Force to Zero

value. – configurable from 0 to at least 5% of full scale

ANALOG INPUTS

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ANALOG INPUTS – Smoothing Factor

• It shall be possible to configure a smoothingfactor for each analog input to ensure that fasttransient interference does not cause largefluctuations in the actual reported value thatcould result in incorrectly reporting limittransgressions.

• The smoothing factor, F, shall be applied asshown:-

Value smooth, new = F*Value new + (1-F)* Value smooth, old

=F(Value new - Value smooth, old )+Value smooth, old

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ANALOG INPUTS

• Some RTUs can also provide other processedvalues such as:- – Min/Max Value – Average Value

– Rate of Change Value• For each input, it is possible to assign alarm

limits for the Low Alarm and for the High Alarm.

When limit is violated, an alarm/event isgenerated and reported to the Control Center.

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CONTROL OUTPUTS – Also referred as digital outputs – Control outputs used to control various

power system devices (breakerTRIP/CLOSE, motor operated switchesOPEN/CLOSE, tap changer RAISE/LOWER,relay RESET, digital setpoint, etc.).

– The control output point shall be in the formof normally open relay contacts. Transistoroutput is not acceptable .

– Some RTUs may have two different digitaloutput modules; one for secure control andthe other for digital output.

SECURE CONTROL D i

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SECURE CONTROL – DesignCriteria

• For secure control, the RTU shall be designed to befail-safe.

• Minimum design criteria: – 1-of-n : Only one control point on a control output

module can be selected or executed at any giventime.

– No false output shall result during power up, powerdown or RTU reset.

– The control selection shall be automatically canceledif after receiving the `control selection‟ message, the`execute‟ command is not the next receivedmessage and/or it is not received within apredetermined configurable time-out period.

SECURE CONTROL D i

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SECURE CONTROL – DesignCriteria

– No false output shall result from a single point offailure. Hardware protection

– The verification message for a check-before-operatecontrol sequence shall be obtained by re-encoding

the verification message directly from the controlpoint selection lines. A simple echoing of thereceived message is not acceptable.

– The RTU‟s control output shall be incorporate

protection to guard against false output selectiondue to a single component failure, erroneousaddress or selection decoding.

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DIRECT OPERATE

• Direct-Operate (Pulse Output) Controls are typically used forcontrolling devices and systems that do not require the controlsecurity as specified in 14.5 above. They can be configured assingle or raise/lower pair output. Direct-Operate (Pulse Output)Controls shall be used for “step” functions such as precisely timedRAISE and LOWER commands to generator controllers. MultipleRAISE/LOWER points can be controlled simultaneously. On

receipt of a command message from the Master Station, a timedpulse is sent to a specified device. The time duration is specified inthe command message. These controls shall be configurable forlatching or pulsed operation.

• Preferred that the RTU supports the Direct-Operate (Pulse Output)Control functionality using the same module as the SecureControl. The control mode, either Secure or Direct-Operate, shallbe configurable using software or hardware methods. The Direct-Operate Controls can, however, be provided as a separate modulethan the Secure Control module.

C t l O t t M d l Oth

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Control Output Module – Otherfunctionalities

• Dummy Circuit Breaker – A latching relay which is installed in the RTU to

simulate a circuit breaker – Used to test control functions

– Status of dummy CB is monitored back• Control Isolate Switch

– A single switch which can be used to disable allcontrol outputs

– Status of switch is monitored by the Control Center

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Firdaus Yon Institut Latihan Sultan Ahmad Shah(ILSAS)

ANALOG OUTPUT• Capability to output analog values (voltage or current) proportional to

digital data received from the Master Station. Analog outputs are used forsuch functions as setpoints for proportional controllers, and data outputsto chart recorders.

• For critical control such as power plant set-point control - select-before-operate analog output control. Less critical control such as meter drive,direct output analog control

• Resolution of the DAC shall be at least 12 bits plus sign ( 4095).

• The output of the AO point shall settle to 0.15% of the digitally encodedvalue within 100 milliseconds of an updated input.• Overall accuracy of the D/A converters shall be 0.15 % of full scale over

the specified operating temperature range of the RTU.• The RTU shall support 4 to 20mA DC analog output (less than 1500 ohm

load). When the Master Station sends a digital value of 0 to the RTU, theRTU‟s analog output shall provide a 4mA signal. Similarly when theMaster Station sends a digital value corresponding to the maximum count,the analog output shall produce a 20mA signal.

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ANALOG OUTPUT• Each analog signal output shall remain at its last set

output level until a new value is sent for the point. In theevent of an RTU malfunction due to communication,the analog outputs shall remain at last sent.

• For 4 to 20mA analog output, the value shall revert to

0mA if the module or the RTU experiences a loss ofpower.

RTU COMMUNICATION

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Firdaus Yon Institut Latihan Sultan Ahmad Shah(ILSAS)

RTU COMMUNICATIONINTERFACES

RTU

SubMaster

Master /Host

Host 2

IED

Satellite RTU

IED protocol

Submaster tosatellite protocol

Slave to Host protocol

* Relay* Smart meter

Slave to Host protocol

RTU MASTER STATION

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RTU – MASTER STATIONCOMMUNICATION

• This session will concentrate on thecommunication ports within the RTU which ismeant for communication with the MasterStation.

• All RTUs will have capability to communicatewith multiple master station independently

• Various channel/port configuration forcommunication with Master Station:- – Single Channel Communication – Main and Standby Port Configuration – Redundant Channel Configuration – Loop/Regeneration /Repeater (WISP+)

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Single ChannelIn a single channel orstandalone configuration, theRTU communicates to thecontrol center through onecommunication port. There is

no redundancy. The RTU maybe connected to the controlcenter in a point-to-point circuitor in a multi-drop network. Thecommunication portconfiguration is as shown.

Ch. A

HOST COMMUNICATION APPLICATION

RTU 1(HCA-RTU 1)

RTU

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Main/Standby Channels• two communication ports are used

for communication with the controlcenter.

• RTU shall monitorcommunications with the MasterStation and in the event of a loss

of communications on the mainchannel, failover from the maincommunication channel to astandby channel shall occur.

• One communication port shall be

assigned as the Main channel andthe other as the Standby channel.

Main Standby

HOST COMMUNICATION APPLICATION

RTU 1(HCA-RTU 1)

RTU

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Redundant Channel• two ports are again used.

• Each of the communication port isconfigured with the same protocoland uses the same or identical pointdatabase within the RTU.

• primary difference is that the RTU

does not decide when to failover orwhich port to communicate through.

• RTU will simply respond to allcommunication traffic from any of theports.

• It will be up to the Master Station todetermine which comm port tocommunicate through.

Ch. A Ch. B

HOSTCOMMUNICATION

APPLICATIONRTU 1

(HCA-RTU 1)

HOSTCOMMUNICATION

APPLICATIONRTU 1

(HCA-RTU 1)

RTU

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Regeneration/loop• Two possible alternatives to this

configuration. The first employs loopswitching and allows the Master Stationto switch between the two channels andto physically divide the loop into twosegments. This allows the MasterStation to communicate through bothchannels on the loop simultaneously aswell as to dynamically reconfigure thenetwork in the case of failures. This is

the present configuration used by RTUsequipped with Ext. WISP+ protocols.

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Regeneration/loop

• The other alternative does not have the capability fornetwork reconfiguration through loop switching. In thisconfiguration, the Master Station has to alternatecommunications between the two channels in the loop toprevent collisions. The Master Station has to ensure thatone channel is connected through a terminating resistorwhen the other channel is communicating. Effectively,the loop switching is carried out at the Master Stationend. For either of this loop switching configurations,communication ports are normally assigned the channeldesignation of the Master Station channel, typicallyeither A or B.

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RTU SUBMASTER• RTU needs to report to the Master Station(s)• RTU can act as Submaster to:-

– Other RTUs (termed as Slave/Satellite RTUs)• Outside the substation

– IEDs (Intelligent Electronic Devices)

• Within the substation

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Submaster RTU – Slave RTUs• Slave RTUs in other

substations• Typically because of

communication limitations• Within substation, use

networked RTU ordistributed I/O concept

• Support Point to PointCommunication

• Support Multidropcommunication

• Protocol – RTU Protocol• Single Submaster can

support multiple protocols

SubmasterRTU

Slave RTU

Slave RTUs

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Submaster RTU – IEDs• As a general practice, tripping alarms from

protection relays are monitored by hard-wiringthe voltage free contacts from the relay to theRTU‟s digital input module. Parameters such asMW, MVAr, current and voltage are monitored

using transducers. Other than these alarms andparameters, TNB may require additional datafrom the protection relays which can be providedthrough a serial communication link. The RTU

shall include all hardware and softwarenecessary to provide an optical interface tonumerical protection relays and intelligentelectronic devices for this purpose.

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Submaster RTU – IEDs• Protocol is IEC 60870-5-103

• The RTU must be able to support communication withat least 32 IEDs on a single channel.

• The RTU shall have the capability to transmitcommands to the microprocessor-based protectionrelays in response to control commands from a SCADAmaster station port, or any other software selectableserial communication port.

• The RTU shall be capable of receiving data availablefrom the microprocessor-based protection relays. It

shall be possible to map these data for transmission tothe SCADA master station.• The RTU shall be capable of receiving disturbance

records available from the microprocessor-basedprotection relays for retrieval by a SCADA masterstation or a local/remote PC through the serial ports.

Programmable Algorithm

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Programmable AlgorithmFunctionality

• Ability to write logic programs in the RTU whichwill allow it to carry out close loop control, likePLCs, as well as other functions such as alarmgrouping, filtering etc.

• TNB has specified Windows-based graphicalprogramming tool that is compliant with theOpen Standard PLC programming languages toIEC 1131-3 (Soft PLC) standard

• Planned algorithms include Capacitor bankswitching, transformer load shedding

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Data Display Interface• Optional Requirement• Capability to support a local backlit LCD display

panel to display RTU status, digital and analoginput points

• Different as compared to using local MMI, i.e.PC communicating with RTU using telecontrolprotocol, although this alternative is alsoacceptable

• More tightly coupled to RTU

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Monitoring & Diagnostic

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Monitoring & DiagnosticSoftware

• Located in the firmware of the RTU processor cards andaccessed using a video terminal (VT) or a personal computer(PC) running a VT100 emulation program.

• Test system connected to the maintenance port of the RTU• Used to:-

– perform all the RTU management, configuration, andexpansion functions;

– monitor all stored data and all RTU inputs in an easy tointerpret format;

– exercise RTU outputs; and to diagnose/troubleshoot the RTU.

Monitoring & Diagnostic

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Monitoring & DiagnosticSoftware

– view the operational status of RTU modules and firmware.

– view the current date and time of the RTU. – monitor current data values (DI, AI & Counters). – monitor the pending/last control output states of the control

points. – view archived SOE data which resides in the respective SOE

buffers.

– view archived analog input and counter values. – allow self-tests to be performed on memory and serial ports. – For analog inputs, view Minimum and Maximum value, Average

value, Rate of Change value, Value in engineering format(Scaled Values)

– monitor communications between the Master Station and RTUs. – Do control in offline, password protected mode – View mapped protocol data

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RTU Configuration Software

• Used to configure the RTU• Configuration shall be stored in non-volatile

memory but not battery back RAM• Ability to upload and download

• Revision control• Report generator capability• Use same maintenance port as the test system

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