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STEAM TURBINES Presentation Transcript
1.STEAM TURBINES
2.ORGANISATION OF PRESENTATION
What is FGMO ?
IEGC guidelines
Facilities available in KWU design sets of BHEL
Problems in implementation of FGMO
Modifications carried in control scheme
Conclusion
What is FGMO ?
IEGC guidelines
Facilities available in KWU design sets of BHEL
Problems in implementation of FGMO
Modifications carried in control scheme
Conclusion
3.FREE GOVERNOR MODE OPERATION (FGMO)
It means that the governor is free to govern as per its regulation/droop characteristics
There are no constraints imposed on it like
- Valve kept wide open
- frequency influence switched off
- dead band for frequency influence
- delibrate time delays
It means that the governor is free to govern as per its regulation/droop characteristics
There are no constraints imposed on it like
- Valve kept wide open
- frequency influence switched off
- dead band for frequency influence
- delibrate time delays
4.OBJECTIVE OF FREE GOVERNOR MODE OF OPERATION
To arrest transient swings in grid frequency
To maintain national grid frequency within IEGC band of 49 to 50.5 Hz
Free governor operation allows the machine to load or unload depending upon whether frequency is lower than or more than the reference frequency
Variation in grid frequency can be minimized by putting all the generating stations on “free governor” mode of operation
To arrest transient swings in grid frequency
To maintain national grid frequency within IEGC band of 49 to 50.5 Hz
Free governor operation allows the machine to load or unload depending upon whether frequency is lower than or more than the reference frequency
Variation in grid frequency can be minimized by putting all the generating stations on “free governor” mode of operation
5.STEADY STATE SPEED REGULATION
IT IS THE CHANGE IN STEADY STATE SPEED
EXPRESSED IN % OF RATED SPEED,
WHEN
THE OUTPUT OF THE TURBINE IS GRADUALLY REDUCED FROM RATED POWER DOWN TO ZERO POWER
WITH IDENTICAL SETTINGS OF ALL ELEMENTS OF THE SPEED GOVERNING SYSTEM
IT IS THE CHANGE IN STEADY STATE SPEED
EXPRESSED IN % OF RATED SPEED,
WHEN
THE OUTPUT OF THE TURBINE IS GRADUALLY REDUCED FROM RATED POWER DOWN TO ZERO POWER
WITH IDENTICAL SETTINGS OF ALL ELEMENTS OF THE SPEED GOVERNING SYSTEM
6.DROOP CHARACTERISTICS
7.EXAMPLE OF NORTHERN GRID
Total installed capacity= 28000 MW
Normally available power (approx.) = 17000 MW
Peak load demand in a day (approx.) = 19000 MW
Hence total shortfall in a day = 2000 MW (approx. 10%)
Therefore, variation in grid frequency should not be more than 0.25 Hz (=0.1*2.5Hz). But in actual the variation in frequency is of the order of 1-1.5 Hz.
Total installed capacity= 28000 MW
Normally available power (approx.) = 17000 MW
Peak load demand in a day (approx.) = 19000 MW
Hence total shortfall in a day = 2000 MW (approx. 10%)
Therefore, variation in grid frequency should not be more than 0.25 Hz (=0.1*2.5Hz). But in actual the variation in frequency is of the order of 1-1.5 Hz.
8.THIS MEANS THAT
Governors are operating in locked condition
To enforce grid discipline, CERC issues guidelines for implementation of FGMO
Governors are operating in locked condition
To enforce grid discipline, CERC issues guidelines for implementation of FGMO
9.INDIAN ELECTRICITY GRID CODE (IEGC)
SECTION 6.2 (E)
ALL GENERATING UNITS, WHICH ARE SYNCHRONISED WITH THE GRID, IRRESPECTIVE OF THEIR OWNERSHIP, TYPE AND SIZE, SHALL HAVE THEIR GOVERNORS IN NORMAL OPERATION AT ALL TIMES. IF ANY GENERATING UNIT OF OVER FIFTY (50) MW SIZE (10 MW FOR NORTH EASTERN REGION) IS REQUIRED TO BE OPERATED WITHOUT ITS GOVERNOR IN NORMAL OPERATION, THE RLDC SHALL BE IMMEDIATELY ADVISED ABOUT THE REASON AND DURATION OF SUCH OPERATION. ALL GOVERNOR SHALL HAVE A DROOP OF BETWEEN 3% AND 6%
10.INDIAN ELECTRICITY GRID CODE
SECTION 6.2 (E)
ALL GENERATING UNITS, WHICH ARE SYNCHRONISED WITH THE GRID, IRRESPECTIVE OF THEIR OWNERSHIP, TYPE AND SIZE, SHALL HAVE THEIR GOVERNORS IN NORMAL OPERATION AT ALL TIMES. IF ANY GENERATING UNIT OF OVER FIFTY (50) MW SIZE (10 MW FOR NORTH EASTERN REGION) IS REQUIRED TO BE OPERATED WITHOUT ITS GOVERNOR IN NORMAL OPERATION, THE RLDC SHALL BE IMMEDIATELY ADVISED ABOUT THE REASON AND DURATION OF SUCH OPERATION. ALL GOVERNOR SHALL HAVE A DROOP OF BETWEEN 3% AND 6%
10.INDIAN ELECTRICITY GRID CODE
11. INDIAN ELECTRICITY GRID CODE (IEGC)
SECTION 6.2 (F)
FACILITIES AVAILABLE WITHIN LOAD LIMITERS, AUTOMATIC TURBINE RUN UP SYSTEM, TURBINE SUPERVISORY CONTROL, CO-ORDINATED CONTROL SYSTEM ETC. SHALL NOT BE USED TO SUPPRESS THE NORMAL GOVERNOR ACTION IN ANY MANNER. NO DEAD BAND AND / OR TIME DELAYS SHALL BE DELIBERATELY INTRODUCED.
SECTION 6.2 (F)
FACILITIES AVAILABLE WITHIN LOAD LIMITERS, AUTOMATIC TURBINE RUN UP SYSTEM, TURBINE SUPERVISORY CONTROL, CO-ORDINATED CONTROL SYSTEM ETC. SHALL NOT BE USED TO SUPPRESS THE NORMAL GOVERNOR ACTION IN ANY MANNER. NO DEAD BAND AND / OR TIME DELAYS SHALL BE DELIBERATELY INTRODUCED.
12.INDIAN ELECTRICITY GRID CODE (IEGC)
SECTION 6.2 (G)
ALL GENERATING UNITS, OPERATING AT / UP TO 100% OF THEIR MAXIMUM CONTINOUS RATING (MCR) SHALL NORMALLY BE CAPABLE OF (AND SHALL NOT IN ANY WAY BE PREVENTED FROM) INSTANTANEOUSLY PICKING UP FIVE PERCENT (%) EXTRA LOAD FOR ATLEAST FIVE (5) MINUTES OR WITHIN TECHNICAL LIMITS PRESCRIBED BY THE MANUFACTURER WHEN FREQUENCY FALLS DUE TO SYSTEM CONTNGENCY.
SECTION 6.2 (G)
ALL GENERATING UNITS, OPERATING AT / UP TO 100% OF THEIR MAXIMUM CONTINOUS RATING (MCR) SHALL NORMALLY BE CAPABLE OF (AND SHALL NOT IN ANY WAY BE PREVENTED FROM) INSTANTANEOUSLY PICKING UP FIVE PERCENT (%) EXTRA LOAD FOR ATLEAST FIVE (5) MINUTES OR WITHIN TECHNICAL LIMITS PRESCRIBED BY THE MANUFACTURER WHEN FREQUENCY FALLS DUE TO SYSTEM CONTNGENCY.
13.SECTION 6.2 (H)
THE RECOMMENDED RATE FOR CHANGING THE GOVERNOR SETTING, I.E. SUPPLEMENTARY CONTROL FOR INCREASING OR DECREASING THE OUTPUT (GENERATION LEVEL) FOR ALL GENERATING UNITS, IRRESPECTIVE OF THEIR TYPE AND SIZE, WOULD BE ONE (1.0) PERCENT PER MINUTE OR AS PER MANUFACURER’S LIMITS. HOWEVER, IF FREQUENCY FALL BELOW 49.5 Hz, ALL PARTY LOADED GENERATING UNITS SHALL PICKUP ADDITIONAL LOAD AT FASTER RATE, ACCORDING TO THEIR CAPABILITY
THE RECOMMENDED RATE FOR CHANGING THE GOVERNOR SETTING, I.E. SUPPLEMENTARY CONTROL FOR INCREASING OR DECREASING THE OUTPUT (GENERATION LEVEL) FOR ALL GENERATING UNITS, IRRESPECTIVE OF THEIR TYPE AND SIZE, WOULD BE ONE (1.0) PERCENT PER MINUTE OR AS PER MANUFACURER’S LIMITS. HOWEVER, IF FREQUENCY FALL BELOW 49.5 Hz, ALL PARTY LOADED GENERATING UNITS SHALL PICKUP ADDITIONAL LOAD AT FASTER RATE, ACCORDING TO THEIR CAPABILITY
14. REALISATION OF DROOP CHARACTERISTICS
In hydraulic control mode these are inherent in the governing system (as the system acts to control speed)
In electrical controller, these are built-up through frequency influence on load setpoint (as the system acts to control load)
In hydraulic control mode these are inherent in the governing system (as the system acts to control speed)
In electrical controller, these are built-up through frequency influence on load setpoint (as the system acts to control load)
15.CHARACTERISTICS OF FREQUENCY INFLUENCE
16.FREQUENCY INFLUENCE SCHEME
(ORIGINAL)
(ORIGINAL)
17.DIFFICULTIES FACED BY UTILITIES
Under FGMO, there is a lot of load cycling and corresponding fatigue in equipment
Parametric variations are beyond allowable limits , leading to unsafe operation.
Utilities find it very difficult to implement supplementary control manually
Boiler is the weak link, it does not have the necessary reserves and there is an inherent delay
Under FGMO, there is a lot of load cycling and corresponding fatigue in equipment
Parametric variations are beyond allowable limits , leading to unsafe operation.
Utilities find it very difficult to implement supplementary control manually
Boiler is the weak link, it does not have the necessary reserves and there is an inherent delay
18.STEERING COMMITTE
A high level committee set up by CEA to examine the issue
View points of Utilities, OEMs, PGCIL and CERC heard by the committee
After deliberations, certain actions were suggested to BHEL and NTPC to address the issues raised by utilities
A high level committee set up by CEA to examine the issue
View points of Utilities, OEMs, PGCIL and CERC heard by the committee
After deliberations, certain actions were suggested to BHEL and NTPC to address the issues raised by utilities
19.RECOMMENDATIONS BY COMMITTEE
To develop a control scheme with floating frequency as the frequency can vary between 49 to 50.5 Hz. The scheme should also automate the process of supplementary control i.e. Load change after 5 minutes
The modified control scheme to be tested at simulator
To suggest suitable changes in the existing control logic of EHC and CMC for safeguarding the boiler, turbine, generator from the effect of rapid changes in frequency
To develop a control scheme with floating frequency as the frequency can vary between 49 to 50.5 Hz. The scheme should also automate the process of supplementary control i.e. Load change after 5 minutes
The modified control scheme to be tested at simulator
To suggest suitable changes in the existing control logic of EHC and CMC for safeguarding the boiler, turbine, generator from the effect of rapid changes in frequency
20.MODIFIED CONTROL SCHEME OBJECTIVES
Reference frequency shall be floating between 49.0 to 50.5 Hz, depending on operating frequency
For any frequency change, load change shall be immediate and limited to +/-5%.
Load change is to be sustained for approx. 5 minutes. If frequency varies during this period, corrective action to be taken again
Reference frequency shall be floating between 49.0 to 50.5 Hz, depending on operating frequency
For any frequency change, load change shall be immediate and limited to +/-5%.
Load change is to be sustained for approx. 5 minutes. If frequency varies during this period, corrective action to be taken again
21.OBJECTIVES
Load shall be brought back to the setpoint in a ramped fashion after five minutes
For frequency < 49.0 and >50.5 Hz , load change to be as per droop characteristics and limited to +/- 10%
Load shall be brought back to the setpoint in a ramped fashion after five minutes
For frequency < 49.0 and >50.5 Hz , load change to be as per droop characteristics and limited to +/- 10%
22. MODIFIED SCHEME
First scheme developed by BHEL and tested at Simhadri simulator at Corporate R&D on 17/07/2004
Step and ramp change in load were simulated
Parameter variations were within allowable limits
It met the set objectives. However, certain changes were suggested
Results were presented to NTPC/ CEA/ PGCIL etc. In 4th and 5th committee meetings. 5th meet was held at Hardwar
It was suggested by Chairman that the scheme be tested at Simhadri site by BHEL & NTPC
First scheme developed by BHEL and tested at Simhadri simulator at Corporate R&D on 17/07/2004
Step and ramp change in load were simulated
Parameter variations were within allowable limits
It met the set objectives. However, certain changes were suggested
Results were presented to NTPC/ CEA/ PGCIL etc. In 4th and 5th committee meetings. 5th meet was held at Hardwar
It was suggested by Chairman that the scheme be tested at Simhadri site by BHEL & NTPC
23. Floating Frequency Setpoint
24. FREQUENCY INFLUENCE SCHEME
(PROPOSED)
(PROPOSED)
25. BLOCK DIAGRAM - CONTROL SCHEME
26. SIMHADRI SITE TRIALS
Scheme was further fine-tuned before and during field trials
Dead band of 0.03Hz was introduced
Trend curves were plotted
These were analyzed and parametric variations were deduced
Scheme was further fine-tuned before and during field trials
Dead band of 0.03Hz was introduced
Trend curves were plotted
These were analyzed and parametric variations were deduced
27. SUMMARY OF TEST RESULTS
28. CONCLUSION
Modified scheme has been accepted by CEA and NTPC
Final report of the committee has been released directing utilities to implement FGMO
Scheme to be implemented by utilities for KWU design sets
Utilities have to place order on BHEL for this work
As of now, LMZ design sets to be put in FGMO (without any modification) and controlled manually
Modified scheme has been accepted by CEA and NTPC
Final report of the committee has been released directing utilities to implement FGMO
Scheme to be implemented by utilities for KWU design sets
Utilities have to place order on BHEL for this work
As of now, LMZ design sets to be put in FGMO (without any modification) and controlled manually
29.Broad features of Scheme implemented at Nasik
The scheme with following basic features was implemented in unit 4 (210 MW LMZ m/c) at Nasik
Load and Turbine inlet Pr changes with frequency variation.
Pressure correction through pulse command to speeder gear motor to restore load when rate of pressure variation is more than 0.2 Kscm/min
Pressure correction through continuos command when pressure variation is more than 2 Kscm
No changes in fuel firing.
A team led by Member, CERC visited Nasik and was satisfied with the response of the scheme
The scheme with following basic features was implemented in unit 4 (210 MW LMZ m/c) at Nasik
Load and Turbine inlet Pr changes with frequency variation.
Pressure correction through pulse command to speeder gear motor to restore load when rate of pressure variation is more than 0.2 Kscm/min
Pressure correction through continuos command when pressure variation is more than 2 Kscm
No changes in fuel firing.
A team led by Member, CERC visited Nasik and was satisfied with the response of the scheme
30. SCHEME IMPLEMENTED IN NASIK (MSEB)
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