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Presentation on “FREE GOVERNOR MODE OPERATION”

Presentation on “FREE GOVERNOR MODE OPERATION”. FREE GOVERNOR OPERATION. FREQ COMPARISION MAY-02 & MAY-03. ROLE. ABT & GOVERNOR. WHY. BEFORE GOVERNOR. GOVERNOR RESPONSE IN NER. BLOCKED GOVERNOR. CHARACTERISTICS. GOVERNOR. GOVERNOR TYPES. GOVERNOR TIME LAG. DEAD BAND. TIME DELAY.

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Presentation on “FREE GOVERNOR MODE OPERATION”

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  1. Presentation on “FREE GOVERNOR MODE OPERATION”

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

  3. ORDERS IEGC 6.2 (e) & 6.2(f) IEGC 6.2 (g) IEGC 1.6 FREE GOVERNOR OPERATION IEGC 6.2 (h) CERC ORDER ON WB dt 02/01/01 KERALA LETTER ON FGM

  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 dependent on frequency • Free Governor Operation • Under Frequency Operation

  7. PRIMARY CONTROL …… (UCPE) Primary control involves the action of turbine speed governors in generating units, which will respond where the speed (frequency) deviates from the speed (frequency) set point as a result of an imbalance between generation and demand in the synchronously interconnected network as a whole. Technical solidarity between members will involve the simultaneous action of primary control on all generating units involved in system control. Next

  8. PRIMARY CONTROL…… (UCPE) The various assumptions, characteristics and parameters applied to primary control are as follows: • The maximum instantaneous deviation ∆P between generation and demand to be corrected by primary control is 2000 MW • For the whole system, with a peak load of the order of 20000 MW and an off-peak load of the order of 12000 MW, assuming 1% self-regulation of load, the quasi-steady-state frequency deviation must not exceed 180 mHz and the instantaneous frequency must not fall below 49.2 Hz in response to a shortfall in generation capacity equal to or less than 2000 MW. The overall network power frequency characteristic for the system is set at 1000 MW/Hz NEXT

  9. FREQUENCY RESPONSE …… (NERC) NERC

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

  11. 2003 2002

  12. HUMAN GOVERNOR OPERATION SYSTEM TG ~ X GOVERNOR

  13. 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

  14. 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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  16. BACK

  17. 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

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

  19. 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

  20. 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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  25. 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.

  26. 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

  27. 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.

  28. 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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  39. 50

  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

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