1. " GOVERNING & PROTECTION SYSTEM"
PRESENTATION ON
SIPAT 660 MW TURBINE
" GOVERNING & PROTECTION SYSTEM"

2. Topics of Presentation
Overview of Turbine
Concept of Governing System
Functioning of EHC Circuits
Turbine Start Up Procedure
TSI & TSC System
Turbine Protection System

3. OVERVIEW OF
TURBINE

4. Turbine Block Diagram

5. Turbine Extractions Ext. No Source Of Extraction
Destination Equipments 1
13th stage of HPT
HPH-8 2
CRH
HPH-7 3
3rd stage of IPT
HPH-6 *
TDBFP 4
6th stage of IPT
DEAERATOR 5
8th stage of IPT
LPH-4 6
11th stage of IPT
LPH-3 7
2nd stage of LPT
LPH-2 8
4th stage of LPT
LPH-1

6. Turbine Components Turbine: HPT, IPT, LPT1 and LPT2
Turbine Bearings: 08
Generator / Exciter Bearings: 04
Turbine Stop Valves: 04 (HPSV-1&2, IPSV-1&2)
Turbine Control Valves: 08 (4 HPCV & 4 IPCV)
CRH Check Valves: 02 ( With Bypass lines for warm up)
Motor driven Shut Off valve in non-stabilized oil line to Check Valve
Motor driven warm up Shut Off valves for HPCV-3 & 4
Governing Box

7. Overview of Governing Box

8. Governing Box Components
Motor operated Control Gear to generate resetting / protection oil & control oil for S.V./ Summators
Two Manual trip devices
Two Over Speed Governor Slide valves (110 % & 111 %)
Two Remote Trip Solenoids
Slide Valve for ATT with two solenoids

9. CONCEPT OF
GOVERNING
SYSTEM

10. Governing System Combination of throttle & nozzle governing
IP Turbine has throttle governing – all four control valves open simultaneously
HP Turbine has nozzle governing – all four control valves open in preset sequence
Resetting of Turbine is done by Control Gear operation
Operation of Stop & Control Valves and CRH Check Valves are done by spring type hydraulic servomotors
Servomotors are closed by spring action during loss of oil pressure

11. Governing System
HPT control valves open only after achieving preset load (12% of 660 MW)
Opening time of control valve is 1.5 sec
Closing time of Stop valve in case of operation of protection is 0.3 sec
Turbine maximum speed is restricted to 108% in case of generator disconnected from grid
Over speed protection system stops steam supply in HPC in < 0.5s
Speed Controller Droop is adjustable from 2.5% to 8% (with dead band of 0.04%)

12. Resetting of Turbine

13. Resetting of Turbine
Stabilized oil pressure of 50 Ksc is supplied to Control Gear
The control gear (AE001) is moved from closed position (0 degree) to open position (90 deg)
Oil is first supplied to reset the over speed governor slide valves
Subsequently Protection Oil is generated and supplied to protection devices
Finally, Control Oil for Stop Valves servomotors & Control Oil for EHC-summators are generated

14. Operation of Stop Valve

15. Operation of Stop & Control Valves
Control Oil pressure in S.V. servomotor moves up slide valve, providing Header Pressure Oil under the piston for S.V. opening
Header Pressure Oil is supplied to C.V. valve servomotors via locking pilot valve & traction/bush arrangements. Opening of C.V. is governed by Control Oil from EHC-Summator
During loss of Header Pressure Oil, the servomotors are closed by spring action
During loss of Control Oil pressure, Bush & Traction of Pilot valve travels up shutting off head pressure oil supply to C.V. servomotors, resulting control valve closing
During S.V. ATT, bush & Traction do not travel up due to slide valve downward movement by ATT motor

16. Components of EHC 1. Speed Controller 2. Pressure Controller
EHC comprises of following controllers:
1. Speed Controller
2. Pressure Controller
3. Load Controller
4. Position Controller

17. Selection of Controls
EHC can be kept in Manual / Auto Mode as per operator’s choice
Manual mode can be selected only when Generator is connected to grid
In Manual Mode, operator can directly open / close the control valves
Controllers can be selected in auto mode through P.B provided on operators console or through interlocks
Controller output in auto mode depends on set point and actual value

18. Speed Control Circuit
Speed Set Point R L
Speed Set Point = 0
Rate Logic
Logic - 2
Actual Speed (Mv3) + -
Speed Controller
O/P
Logic-1
Logic 1: Turbine protection operated / 2v4 stop valves closed / 2v3 speed measuring channels faulty / Deviation between actual speed and set point during run-up exceeded allowable value*
Logic 2: Speed gradient is controlled by minimum of TSE margin & gradient from selected Start up curve, given by the Turbine Manufacturer Contd….

19. Rolling Speed Gradient Curve
Speed gradients as per Manufacturer’s start up curve are as follows:
Rolling Condition
Target Speed
Preset Time
Min. Halt Time
Cold Startup ( > 72 H )
rpm
150 sec
300 sec
1200 rpm*
550 sec
3000 rpm
630 sec
Between 36H – 72H
75 sec
120 sec
240 sec
Between 8H – 36H
rpm
360 sec
Between 2H – 8H

20. Speed Control Circuit
Speed Controller will be switched on automatically in case generator breaker opens (with Turbine controller on auto) or Turbine trips
Turbine speed measurement is be done by using 3 sensors (eddy current type)
The mean* of the three sensors is taken as actual speed
Incase of one sensor fault, maximum of rest two sensors will come in service
Incase of two sensor fault, Turbine trip signal is generated to trip the turbine

21. Speed Control Circuit Speed Ref Tracking:
After Synchronization, with other controller in service, the speed controller tracks the actual speed between 49HZ to 51HZ (adjustable)
Islanding Mode:
If actual speed exceeds speed reference by a preset limit under Generator Breaker in closed condition, Islanding mode occurs – Transferring Turbine to Speed Control mode

22. Load Control Circuit
Load Control On: Load Controller will be switched on automatically if Turbine controller is kept on auto and connected to the grid under “Turbine Latched” condition.
Load Control Off: Load controller will be switched off under following conditions:
1. Manual control mode is switched on
2. The Generator has disconnected from the grid
3. The grid frequency has gone beyond allowable limits
4. Load Measurement faulty (2/3 sensors faulty)
5. M.S. Pres. measurement faulty (2V3 sensors faulty)
6. Unit is in Pressure Control mode

23. Load Control Circuit
Load Ref R L
Delay Element
Max.Load Lim.
Min.Load Lim.
Correction C.K.T
Freq. Corr
Press. Corr
Fast Tracking
Actual Load + -
O/P
Logic - 4 5 6
STOP 3 2 1
Logic-1: CMC ON, when load ref. will come from CMC circuit, where TSC
Margin calculation controls the gradient
Logic-2: The Load reference tracks actual load for bump less transfer
once it is connected to the grid.
Contd…

24. Load Control Circuit 1. TSC Margin is less than permissible value*
Logic-3: Load Reference will be stopped under the following Conditions:
1. TSC Margin is less than permissible value*
2. The difference between the actual and reference value is not in allowable range
Logic-4: Maximum and minimum load set points, set by the Operator
Logic-5: External Frequency Influence ON - actual frequency will be tracked at a predefined delayed rate, with an adjustable droop to help in loading and unloading of the machine within a band of frequency
Contd…

25. Load Control Circuit
Logic – 6: The Pressure correction is divided into two Parts:
1. Before the “HPC On” is generated, the pressure correction will be calculated with R.H. pressure
2.After “HPC On” is generated, the pressure correction will be calculated with M.S pressure
HPC On: The point at which the HP Control Valves starts Opening (12% of full load)
Load Measurement: Three Transducers with mean* value selection
Incase of one of the transducer failed, maximum of rest two.will be selected

26. Pressure Control Circuit
Pressure Control is switched ON by the operator or automatically through Turbine Control on auto when HPC is in operation
Pressure Controller is automatically deactivated under the following conditions:
1. GCB Open
2. The frequency is more than allowable value*
3. M.S. pressure transducers failed (2V3)
4. Manual Control switched on
5. Load control is On
6. HPC is out of operation

27. Pressure Control M.S. pressure set point is dictated by Boiler Master
Adder Block PI
Controller
MIN
MAX +
Actual Pr. Value
O/P -
M. S. Pr. Set Point
Minimum Pr.
Controller
Control Stage Max
Pr. Controller
M.S. pressure set point is dictated by Boiler Master
Limitation of pressure drop to impermissible value is ensured by minimum pressure controller
Limitation of pressure rise to impermissible value is ensured by a protective control stage maximum steam pressure controller, which comes into operation through maximum value selector

28. Position Control Circuit
MV2
Posn. F/B - 1
Posn. F/B - 2
Control Signal From TC + - PI
MIN
Limiter
O/P- (0-150mA)
Biasing Current 0.8 to 1A
TO I/H
CONVERTOR
A PI controller is used to generate the signal to the current amplifiers through Limiter
Command to HP control valves extends under “HPC ON” condition
Loss of current signal to I/H Converter results in closing of the C.V.

29. Operation of I/H Converter

30. Operation of I/H Converter
I/H Converters control the opening and closing of the corresponding control valves
Individual I/H converters get command from Turbine controller
50 Ksc Header Pressure Oil holds the piston (2) up against spring action
As the slide valve (1) moves as per I/H converter, 35 Ksc control oil output is regulated for C.V. servomotor operation
When 50 KSC Governing oil pressure collapses, piston (2) travels down due to spring action – thus draining the oil line of C.V. servomotor

31. Control Valve Opening Curve

32. Turbine Start Up Sequence
Start Turbine rolling with Speed Control on from barring speed to 500 rpm
After achieving desired criteria, raise speed set point to rpm* and subsequently to 3000 rpm
After synchronization Load Controller gets switched On – raise load > 80MW when “HPC ON” signal is generated
Turbine Pressure Control will be automatically switched On
After HPCV demand crosses 80%, switch ON Position controller to hold 80% as the o/p to control valves for raising pressure to rated value
Switch ON Pres. Controller to raise load to rated value
Switch ON Load Control after load reaches the rated value

33. START UP CURVES OF TURBINE AFTER SHUTDOWN OF THE UNIT

34. Start Up Curves Nomenclature
To – S.H Live steam temperature.
Trh – R.H steam temperature
Po – S.H outlet steam pressure
Prh – R.H. steam pressure
Go – Electrical Load of TG
Ne – Live steam flow from boiler
N – Turbine rotor speed
A – Steam Admission
B – Synchronization
C – HPC switch on
D – HPCV open with 20% Throttle reserve & Loading with constant HPCV position & HP heaters charged
E – HPCV no-3 opening. Throttle pressure reduced
F – Full Load

35. START UP CURVES OF TURBINE AFTER SHUTDOWN OF THE UNIT

36. START UP CURVES OF TURBINE AFTER SHUTDOWN OF THE UNIT

37. TSI & TSC
SYSTEM

38. Turbovisory Instruments
Turbo Generator consists of 12 bearings – 8 for Turbine & 2 for Generator & 2 for Exciter
For Bearing no. 1-10, abs. brg. vibration is measured in 3 components (Horizontal, Vertical & Horizontal axial)
For Bearing no. 11 & 12, abs. brg. vibration is measured in 2 components (Horizontal & Vertical)
Absolute shell vibration is measured for all the bearings in 2 components (Horizontal & Vertical)

39. Turbovisory Instruments
Rotor Relative Vibration is measured in all the bearings in 2 components
Absolute Rotor Vibration is derived from Absolute Bearing Shell Vibration and Rotor Relative Vibration for all the bearings
Axial Shift measurement is done in Bearing no. 3
Eccentricity measurement is done in Bearing no. 1
Turbine Speed sensors and Key phasor are Installed in Bearing no. 1

40. Turbovisory Instruments
Brg. No.
Abs. Brg. Vib.
Abs.ShelVib.
(2Comp)
Rel.Rotor Vib.
(2 Comp)
Ang. Dis. Brg. Shell
Casing Exp.
Rotor Exp.
3 Comp
2 cmp 1 Y N
Y (HPC) 2 3 4
Y (IPC) 5 6
Y (LPC-1) 7 8
Y (LPC-2) 9 10 11 12

41. TSC System
The Stress Margin of the Turbine is calculated by measuring the temperatures of following components:
1. HPC Rotor and Outer Casing
2. IPC Rotor and Outer Casing
3. 2 HP Stop Valves
4. 2 IP Stop Valves
5. 4 HP Control Valves
6. 4 IP Control Valves

42. PROTECTION SYSTEM

43. Turbine Protection System
Turbine protection system consists of Two Independent channels, each operating the corresponding solenoid (220V DC) to trip the Turbine in case of actuation of remote protection
Hydraulic Protection: Apart from the Electrical Trip, Turbine is equipped with the following Hydraulic Protections:
1. Local Manual Trip (1V2)
2. Over speed Trip #1 at 110% of rated speed
3. Over speed Trip #2 at 111% of rated speed
4. Governing oil pressure < 20 Ksc
Contd..

44. Turbine Protection System
Contd…

45. Turbine Protection System
Axial shift Very High (2V3) [-1.7mm, +1.2mm]
Turbine bearing vibration : Very High (2V10 including X & Y directions)* >11.2mm/sec (Td=2 sec)
Lube oil tank level very Low (2V3)* Td=3sec (Arming with two stop valves open)
Lub oil pressure Very Low (2V3) < 0.3 Ksc; Td =3 sec (Arming with two stop valves open)
Condenser pressure Very High (2V3) > - 0.7ksc
(Arming with condenser press < 0.15 ksc Abs)
Contd..

46. Turbine Protection System
M.S. temp Very Low (2V3) < 470 deg C (arming > 512 deg C)*
M.S. temp Very High (2V3) > 565 deg C*
HRH temp Very Low (2V3) < 500deg C (arming > 535 deg C)*
HRH temp Very High (2V3) > 593deg C*
HPT outlet temperature Very High (2V4) > 420 deg C
Contd…

47. Turbine Protection System
Gen seal oil level of any seal oil tank Very Low (2V3)* < 0 mm;Td=15 sec (Arming with any two stop valves open)
All Generator seal oil pumps OFF (3V3)* Td: 9 sec (Arming with any two stop valves open)
Generator Stator winding flow Very Low (2v3) < m3/hr; Td =120 sec (Arming with any two stop valves open)
Generator hot gas coolers flow Very LOW (2V3)* : <180m3/hr; Td=300sec(Arming with any two stop valves open)
Generator cooler hot gas temp. Very High(2V4) > 85 deg (Td = 300sec
Contd…

48. Turbine Protection System
MFT operated: (2V3)
Deareator level Very High (2V3) > 3400 mm*
HP heater level protection operated (2V3)*
Generator Electrical protection operated (2V3)
Turbine over speed protection operated (114%)
Turbine Controller failure protection operated (2V3)
Contd…

49. THANK YOU