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ELECTRO

HYDRAULICTURBINE CONTROL

IN

TRIPPLE MODULE

REDUNDANCY

CONFIGURATION

R.N. MANIK


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INTRODUCTION

The development of technology is increasing day by day towards

high availability of closed and open loop in critical control.Previously mechanical hydraulic control was used very extensively

& now because of the development of electronics, reliability o

electronic control has increased many folds. This resulted inreplacement of hydraulic control by electronic control.

The new technology implemented in our unit 2 & 3 of turbinecontrol is named as Triple Modular Redundant Control on

EHTC and Turbine Protection. The new technology demandsmodern Electro hydraulic actuator i.e. high-pressure actuators.


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DEMANDS OF TMR CONTROL

NO BACKUP MECHANICAL GOVERNERNO BACK UP PROTECTION SIMPLIFIED HYDRAULIC / GOVERNING SYSTEM

(ONLY ONE OIL LINE)

FUNCTION OF LSR,HP/IP TRIM DEVICE AND ATTDEVICES ARE CHANGED FROM HYDRAULIC TO

ELECTRONIC SYSTEM

IMPROVED AVAILBILITY AND RELIABILITY INDEPENDENT CONTROL FOR EACH VALVE

(CONTROL AND TRIP)


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CONFIGURATION OF TURBINE CONTROL IN UNIT # 2 & 3

IPB-2(DUAL LINE)

BACK UP

PANELWS POSE

TSE

CJJ01CCA02 &

03

CCA

01

TP

CJJ32

EHTCMON

CJJ31

CCA

05

CCA

04

LPBP&GSPC

CJJ03

TMR-1

CJJ21

TMR-2

CJJ22

TMR-3

CJJ23

POS.CNT

CJJ24

TRIPSOV

CJJ34

ANALOG DIGITAL

SIGNALRLTD TO

EHTC/TP

TRIPSOLENOIDFOR SV s &

CVs

SERVOVALVE FOR

CVs

TMR-1

CJJ21

TMR-2

CJJ22

TMR-3

CJJ23

SGNLCOND

CJJ07

SGNLCOND

CJJ33


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TMR PHILOSOPHY

1. INPUT SIDE

A. SIGNAL FROM FIELD IS ACQUIRED FIRST IN SIGNAL DISTRIBUTION

PANEL, FROM WHERE THESE SIGNALS ARE DISTRUBATED TO

INDEPENDENT TMR

EXAMPLE :

MAIN STEAM TEMPERATURE -1

SIGNAL CONDITIONING PANEL

TMR-1 TMR-2 TMR-3



TMR-1 TMR-2 TMR-3



TMR-1 TMR-2 TMR-3


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UA 374

TMR CH-1 + ANALOG SIGNAL

DISTRIBUTION TMR CH-2

- CARD

SENSORS ( 4 - 20 MA ) TMR CH-3

UT 371 TMR CH-1

NC

DIGITAL SIGNAL TMR CH-2

COM DISTRIBUTION

CARD TMR CH-3

NO

TMR CH-1

TMR CH-2

TMR CH-3

SIGNAL DISTRIBUTION TO TMR CHANNELS


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ARRANGEMENT OF SPEED PROBE SIGNAL DISTRIBUTION FOR EHTC SPEED ACQUISITION IN TMR

AND OVER SPEED PROTECTION TRIP

CH-A TURBINE TRIP

EI05 EI05 EI05

CH-B TURBINE TRIP

EI05 EI05 EI05

EHTC TMR-1 EHTC TMR-2 EHTC TMR-3

TP TMR-1 TP TMR-2 TP TMR-3

TURBINE

SHAFT

SPEED

PROBE-1

23 4

56

O/S RLY LT RLY COIL

O/S RLY LT RLY COIL


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10/34

POSITIONCONTRO

LLERREF-1

POSITIONCONTROLLER

REF-2

S

EL

SE

L

EHTCTMR-1 / TMR-2 / TMR-3

SERVO SERVO

COIL-1 COIL-2

HPCV1, HPCV2

IPCV1 AND IPCV2


11/34

CHANGEOVER LOGIC OF TMR

POSITION SET POINT OUTPUT MODULE FAULTY

POSITION SET POINT OUTPUT MONITORINGMODULE ( ASABA13 ) DISCREPANCY FAULT

PROCESSOR FAULT ( BOTH MASTER & SLAVE)

COMMUNICATION FAULT ( PROPOSED )


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EHTC control consisting of thefollowing main components

turbine start up and lift limiter

speed controller

load controllerpressure controller


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TSLLE RAISE/LOWER

STARTING FUNCTION TMR

DEVICE GENTR FAULT CHANGEOVER

STATION

SPEED SPEED SPEED SLC HPCV1

REFERENCE REF. DLD ERROR HPCV1 M SWITCHING POSN SERVO

S I CKT CONTLLER

SPEED W CHART N

ACTUAL I CKT

T POSN ACT

C SLC HPCV2LOAD LOAD LOAD H PD HPCV2 M SWITCHING POSN SERVO

REFERENCE REF. DLD ERROR I CONTRO I CKT CONTLLER

N LLER CHART N

G CKT

LOAD POSN ACT

ACTUAL C SLC IPCV1

I TRACKING IPCV1 M SWITCHING POSN SERVO

R FROM I CKT CONTLLER

C 2 & 3 CHART N

PRESSURE PRES. U TMR CHNL CKT

REFERENCE ERROR I POSN ACT

T SLC IPCV2

PR. IPCV2 M SWITCHING POSN SERVO

ACTUAL I CKT CONTLLER

CHART N

CKT

POSN ACT

FUNCTIONAL BLOCK DIAGRAM OF EHTC IN TMR IMPLEMENTATION


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TURBINE SART UP AND LIFT LIMITING EQUIPMENT

( TSLLE )

SIMILLAR TO STARTING DEVICE OF UNIT NO-1, THE TSLLE CAN BE OPERATED FROM

THE TURBINE CONSOLE OF CONTROL ROOM

THE FOLLOWINGS ARE THE STEPS ON TSLLE RAISE

TSLLE > 7.5 %

ONE OF THE TURBINE PROTECTION RELEASED

TSLLE > 12.5 %

TURBINE PROTECTION RESET IN LOGIC SIDE

TSLLE > 22.5 %

PARTIAL TRIP RESET FOR STOP VALVE.

TSLLE > 32.5 %

PARTIAL TRIP RESET FOR CONTROL VALVE.

TSLLE > 42.5 %

STOP VALVE OPENING

TSLLE > 50 %

START INCREASE OF CONTROL OUTPUT FROM ZERO

RELEASE TO INCREASE THE TSLLE

1. EHA OIL PRESURE ADEQUATE i.e. CONTROL OIL PR > 150 KG/CM2


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TSLLE POSITION REFERENCE VSTSLLE OUT PUT TOWARDS CONTROLLER OUTPU

T

S

L 100%

LE

O

U

TP 50 %

U

T

-10%

25% 50% 75% 100%

TSLLE POSITION REFERENCE

( 68 %, 47.5 % )

( 46 %, -10% )

( 90 %, 105 % )


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TSLLE OUTPUT(%) V/S HPCV1 POS

(MM)

0102030

405060

12

.5

32

.5 50

55.97

59.46

71.13

80

.3

86.89

88.01

TSLLE OUTPUT(%)

HPCV1P

OS

(MM)


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TSLLE O/P( %) V/s HPCV2 POS. ( MM)

0

10

20

30

40

50

12.5 32.5 50 55.97

59.46

71.13 80.3 86

.8988

.01

TSLLE OUTPUT in %

HPCV2P

OS.IN

MM


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TSLLE O/P (%) V/S IPCV1 POS. (MM)

0

20

4060

80

100

12.5

32.5 50

55.97

59.46

71.13 80

.386

.8988

.01

TSLLE O/P (%)

IPCV1PO

S.

(MM)


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TSLLE O/P (%) V/S IPCV2 POS.(MM)

0

20

4060

80

100

120

12.5

32.5 50

55.97

59.46

71.13

80.3

86.89

88.01

TSLLE O/P (%)

IPCV2P

OS.(MM)


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SPEED CONTROLLER ACTIVE

UNDER FOLLOWING CONDITION

LOAD WITH SPEED CONTROL SELECTED AND LOAD ACTUAL IS LESS THAN15 MW

LOAD ACTUAL WILL INCREASE/DECREASE THROUGH LOAD REF.

IN NORMAL OPERATION (i.e. TURBINE IS IN LOAD CONTROLLER ), IF

1. LOAD SHED DETECTED SIGNAL APPEARS OR

2. GCB OFF

3. DVC ISOLATED (UNIT-2 ONLY )


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SPEED REFERENCE BLOCK

UNDER FOLLOWING CONDITIONS:

GENERATOR CIRCUIT BREAKER OFF

AND

( Nrtd Nact ) > 36 rpm

OR


AND

SPEED/LOAD SP BLOCK FROM SGC TURBINE

AND

SPEED REFERENCE Nr > N rtd

AND

SPEED REFERENCE Nr < 2850 rpm


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DN/DT MONITORING


AND

RATE OF CHANGE OF SPEED ACTUAL 5 RPM / 3 SEC

AND

CONTROLLER O/P MORE THAN 1%

AND

SPEED ACTUAL BETWEEN 725 TO 2850

ON DN/DT OPERATION SPEED ACTUAL WILL BE LOWEREDAUTOMATICALLY BELOW 725 RPM


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LOAD CONTROLLER ACTIVEUNDER THIS CONDITION

LOAD WITH LOADCONTROLSELECTED

AND

GCB ON


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BARE SPEED CONTROLLER ACTIVE


GCB ON , LOAD SET POINT OFF ( TURBINE CONTROL IS IN SPEED

CONTROLLER) AND

LOAD SHED DETECTED

GCB ON , LOAD SET POINT OFF ( TURBINE CONTROL IS IN SPEED CONTROLLER)

AND

FRQUENCY > 53 HZ

ON BARE SPEED ACTIVE WITH LOAD SHED DETECTED

1. SPEED REFERENCE BECOMES 3000 RPM FOR 5 SEC

AFTER THAT LOAD CAN BE INCREASED AND DECREASED THROUGH SPEED

REFERENCE ONLY.

ON BARE SPEED ACTIVE WITH FREQUENCY > 53 HZ

2. LOAD CAN BE INCREASED AND DECREASED THROUGH SPEED

REFERENCE ONLY.


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BARE SPEED CONTROL

1. GCB ON

2. LOAD SP OFF3. LOAD SHED DETECTED OR FREQUENCY MORE THAN 53 HZ

SPD ACT

M

AS

T

E

RC

O

NT

R

Nr Nrtd Speed

controller


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LOAD SHED DETECTED


LOAD ACTUAL IS LESS THAN 15 MW AND FREQUENCY IS MORE THAN 53 HZ

( DURING SYNCHRONISATION & FREQUENCY >53 HZ)

ARMING :- LOAD IS MORE THAN 15 MW ONCE

LOAD REFERENCE IS MORE THAN LOADACTUAL BY 5 MW AND LOAD

ACTUAL IS LESS THAN 15 MW(THIS CAN HAPPEN IN CASE OF SUDDEN LOAD THROW OFF IN THE GRID)

EXAMPLE: - LOAD REFERENCE = 13 MW

LOAD ACTUAL = 7 MW


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LOAD REJECTION ACTIVATED

UNDER THIS CONDITION

LOAD ACTUAL THROWN OF MORE THAN 60 MW

AND

RESIDUAL LOAD ACTUAL < 22.5 MW

ON LOAD REJECTION ACTIVATED

SPD/LOAD CONTROLLER OUTPUT TO ALL CONTROL VALVES

(HPCV1/2 AND IPCV1/2) BECOMES ABSOLUTELY ZERO FOR 1SEC.

AFTER THAT COME BACK TO CONTROLLER OUT PUT ACTUAL.

EXAMPLE: LOAD ACTUAL = 85 MW

THROWN LOAD = 65 MW

RESIDUAL LOAD = 20 MW


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FREQUENCY VSPR MAX120

100

80

LOAD

MW 60

40

20

0

52.50 52.6 52.7 52.8 52.9 53 53.1 53.2

FREQUENCY


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HP EXHAUST TEMPERATURE CONTROLLER

MIN HP EXHAUST REFERENCE

HP SHAFT MEAN TEMP.

HP EXHAUST

TEMPERATURE

FLANGE TEMP. CONTROLLER CONTROLLER OUTPU

HP EXHAUST TEMP. TO IPCV

30% HIGH

0% LOW

FKG

FKG


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DVC ISOLATION SCHEME


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ON DVC ISOLATION THE

FOLLOWING ACTIVITIES WILL

TAKE PLACE Load controller will switch over to speed

controller

Speed reference will be changed to calculated

value with respect to last load reference to hold

the load.

Valve lifting will instantly change and come to

original valve lifting after correction o

frequency ( which will be approximately 51.5

Hz) To maintain the frequency and load as per

requirement, LOAD REFERENCE has to be

adjusted by the operator (not through speed

ref.).


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TO MAINTAIN ACTUAL SPEED

AROUN D 51 .5 HZ D URING DVC ISOL

SPEED ACTUAL SELECTED

ON "LOAD SP ON" FOR SPEED REF TRACKING

ADS UMS

51.5 HZ

50 HZ

OPERATOR SET SPD REF.

SMU

FOR BLOCK LOAD SWITCH

FLIP FLOP

LOAD SETPOINT ON

OR

FOR SYNC.

FOR DVC ISO

0.09

0.05

SEL 2

2

1

S

R

GCB OFF

TURBINE TRIP

INT

T

>

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