POWER GRID CORPORATION OF INDIA LIMITED

1. POWER GRID CORPORATION OF INDIA LIMITED Presentation on ‘FREE GOVERNOR OPERATION”

2. FREE GOVERNOR OPERATION FREQ COMPARISION MAY-02 & MAY-03 ROLE WHY ABT & GOVERNOR BEFORE GOVERNOR GOVERNOR RESPONSE IN NER BLOCKED GOVERNOR CHARACTERISTICS GOVERNOR TYPES GOVERNOR GOVERNOR TIME LAG DEAD BAND TIME DELAY BACKLASH DROOP FREQUENCY DECAY RATE TYPES OF CONTROLS DROOP RESPONSE IN SR ADVANTAGES PROBLEMS LIST OF GENERATORS FREQUENCY BASED DISPATCH FREQUENCY BASED DISPATCH SUPPRESSED GOVERNOR ACTION PID CONTROL PTI TAPE ORDERS

3. ORDERS IEGC 1.6 IEGC 6.2 (e) & 6.2(f) IEGC 6.2 (g) IEGC 6.2 (h) NLY PETITION WEST BENGAL

4. ROLE OF SYSTEM OPERATOR • LOAD GENERATION BALANCE 50

5. WHY DOES FREQUENCY DROP ? Sudden addition of load causes a drop in frequency. An increased load is supplied through an increase in the load angle by which the rotor lags the stator field. It means a loss of Kinetic Energy of the rotating M/c and a slower speed of rotation i.e. a lower frequency. f = (P/2) X (N/60) Where f = frequency of the system P = no of poles of the M/c. N = rpm of the M/c. Next

6. PRIMARY CONTROLS • Load Frequency control • Free Governor Opertaion • Under Frequency Operation

7. ABT AND GOVERNOR POST ABT FREQUENCY WITHIN 49 TO 50.5HZ ACHIEVED BY STAGGERING OF LOADS FLUCTUATION IN FREQUENCY INCREASED Show Me

8. 2003 2002

9. HUMAN GOVERNOR OPERATION SYSTEM TG ~ X GOVERNOR

10. GOVERNOR SPEED GOVERNOR IS THE CONTROLLING MECHANISM WHICH CONTROLS THE INPUT TO THE PRIME MOVER AUTOMATICALLY WHEN THERE IS A CHANGE IN SYSTEM SPEED (FREQUENCY) WHEN THERE IS A CHANGE IN SYSTEM FREQUENCY GOVERNOR RESPONSE BY CAUSING VALVES/GATES TO OPEN/CLOSE TO INCREASE/DECREASE THE INPUT TO THE PRIME MOVER Next BTG

11. MISCONCEPTION Governors attempt to restore frequency to normal. In reality, Governors attempt to restore load generation balance, using frequency change as a signal. Next

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14. 1. Respond promptly to a small change in speed. 2. Adjust the throttle valve with a minimum of overshoot. 3. Have sufficient power to overcome friction losses and unbalance forces in the throttle valve. 4. Permit very little speed fluctuation under constant load and steam conditions. CHARACTERISTICS

15. Mechanical shaft Direct acting orifice Oil relay Precision oil relay Electronic governor TYPES OF GOVERNORS

16. DEAD BAND DEAD BAND OF THE SPEED GOVERNORING SYSTEM IS THE TOTAL AMOUNT OF CHANGE IN STEADY STATE SPEED WITHIN WHICH THERE IS NO ACTION BY GOVERNOR. IEC - 45

18. DROOP CHARACTERISTICS THE AMOUNT OF SPEED (OR FREQUENCY) CHANGE THAT IS NECESSARY TO CAUSE THE MAIN PRIME MOVER CONTROL MECHANISM TO MOVE FROM FULLY CLOSED TO FULLY OPEN. NORMAL RANGE - 3 TO 5% THE MINIMUM RATE OF CHANGE OF SPEED SHOULD NOT BE LESS THAN 0.4 TIMES OF ITS DROOP. THE MAXIMUM RATE OF CHANGE OF SPEED SHOULD NOT BE MORE THAN 3 TIMES OF ITS DROOP. Next

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24. GOVERNOR TIME LAG TIME TAKEN BY GOVERNOR TO JUST BEGIN CHANGING POWER OUTPUT TO STABILISE FREQUENCY. OR TIME BETWEEN A CHANGE IN GENERATOR SPEED & CHANGE IN TURBINE POWER.

25. TIME DELAY IN GOVERNOR OPERATION • Dead band 0.25 sec • Valve opening 0.5 sec • Steam flow 4 seconds • During transient state Governor is of little help. • Effect is felt during steady state

26. BLOCKED GOVERNOR • BYPASSING THE GOVERNING FEEDBACK MECHANISM TO MAINTAIN FIXED GENERATOR OUTPUT. • DISADVANTAGES:- • SYSTEM INSTABILITY • RESTORATION OF SYSTEM FREQUENCY TO NORMAL TAKES MORE TIME AFTER A DISTURBANCE.

27. FREQUENCY DECAY RATE Approximate Freq 5 X Lost Generation Decay Rate = -------------------------------------- In Hz / sec Remaining Generation Example:- 2200MW 200MW Generation Lost Freq decay rate = (5 X 200) / 2000 = 0.5 Hz /second

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34. 49.1 49.2 49.3 49.4 49.5 49.6 49.7 49.8 49.9 POINT C POINT D POINT B POINT A POINT A - GENERATION LOSS POINT B – GOVERNOR ACTION STARTED POINT C - FREQUENCY AFTER GOVERNER ACTION POINT D – FREQUENCY AFTER OPERATOR ACTION

35. BACKLASH The distance through which one part of connected machinery, as a wheel, piston, or screw, can be moved without moving the connected parts.

36. BOILER CONTROLS • BOILER FOLLOWING SYSTEM • TURBINE FOLLOWING SYSTEM • INTEGRATED CONTROL SYSTEM SHOW SYSTEM

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40. ADVANTAGES • Reduce the random change of frequency • Mitigate effect of load generation mismatch • Prevents wastage of fuel during low load condition • Faster restoration from grid disturbance

41. Steam deposits on the valve stem . Lubrication deposits (i.e., soaps, dirt, detergents, etc.) in the top works of the valve exposed to the elements. Mechanical failures of the valve resulting from bent stems, either in the valve proper or the upper works, damaged split couplings, etc., all within about a 6" area near the center of the valve mechanism. Galling of the piston in the hydraulic latch cylinder. Jamming of the screw spindle in the larger cylinder-type valve design due to forcing by operations personnel PROBLEMS

42. FREE GOVERNOR OPERATION • Mother of all Controls • Self healing mechanism • Collectively Control • Most equitable • Reduces risk of collapse • Makes restoration easy • World wide mandatory practice

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44. STEADY STATE OPERATION AT 50 HZ GEN= 190MW NEXT

45. OVER GENERATED BY 5% FREQUENCY DIPPED TO 49.8 HZ GENERATION INCREASED BY 10 MW NEXT

46. OVER GENERATED BY 5% NEXT

47. STEADY STATE OPERATION AT 50 HZ GEN= 190MW NEXT

48. INITIAL FREQUENCY RISE UPTO 50.2 HZ GENERATION DECREASED BY 17MW UI PRICE = 84 Ps NEXT

49. INITIAL FREQUENCY RISE UPTO 50.2 HZ GENERATION DECREASED BY 17MW UI PRICE = 84 Ps NEXT

50. SINCE VARIABLE COST OF STATION A > STATION B FINAL GENERATION FURTHER REDUCED BY 17MW NEXT