Sarath Chandrasiri / EPD / MEW DYNAMIC RESPONSE OF GAS TURBINES PRESENTED BY: THE DIRECTORATE OF ELECTRICITY PRODUCTION  K. A. CHANDRASIRI

Sarath Chandrasiri / EPD / MEW THE NEXT SLIDE ILLUSTRATES THE IMPORTANCE OF THE SUBJECT

Sarath Chandrasiri / EPD / MEW MY DYNAMIC RESPONSE IS NOT OK

Sarath Chandrasiri / EPD / MEW RESPONSE FOR SLOW VARIATIONS OF FREQUENCY

Sarath Chandrasiri / EPD / MEW P-f CHARACTERISTIC OF THE SYSTEM LOAD

Sarath Chandrasiri / EPD / MEW SYSTEM LOAD SYSTEM FREQUENCY (f) 50 Hz INCR DECR DEMO NEXT SLIDE

Sarath Chandrasiri / EPD / MEW POWER OUT PUT OF GENERATOR SYSTEM FREQUENCY (f) 50 Hz GENERATOR CHARACTERISTIC LOAD FREQUENCY CHARACTERISTIC OF THE GENERATOR

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (f) f Hz SYSTEM LOAD CHARACTERISTIC GENERATOR CHARACTERISTIC POWER (MW)

Sarath Chandrasiri / EPD / MEW POWER (MW) SYSTEM FREQUENCY (Hz) 50 SYSTEM LOAD GENERATION DEMO NEXT SLIDE

Sarath Chandrasiri / EPD / MEW THE STEADY STATE POINT OF OPERATION OF THE SYSTEM IS THE POINT OF INTERSECTION OF: SYSTEM LOAD CHARACTERISTIC and GENERATOR CHARACTERISTIC THE SYSTEM FREQUENCY IS THE FREQUENCY CORRESPONDING TO THIS POINT

Sarath Chandrasiri / EPD / MEW STRATEGY FOR MAINTAINING THE SYSTEM FREQUENCY AT 50Hz IS TO KEEP ADJUSTING THE GENERATION CURVE SO THAT IT INTERSECTS WITH THE SYSTEM LOAD CURVE AT 50 Hz

Sarath Chandrasiri / EPD / MEW PROPERTIES OF THE SYSTEM LOAD CHARACTERISTIC

Sarath Chandrasiri / EPD / MEW GENERATOR RESISTIVE LOAD ADJUST TURBINE GOVERNOR FREQUENCY SENSITIVE LOAD (Induction motor)

Sarath Chandrasiri / EPD / MEW POWER (MW) SYSTEM FREQUENCY (Hz) SYSTEM LOAD CHARACTERISTIC GENERATION CHARACTERISTIC 1 SYSTEM WITH ROTATING LOADS NEXT SLIDE

Sarath Chandrasiri / EPD / MEW GENERATOR RESISTIVE LOAD ADJUST TURBINE GOVERNOR

Sarath Chandrasiri / EPD / MEW POWER (MW) SYSTEM FREQUENCY (Hz) SYSTEM LOAD CHARACTERISTIC GENERATION CHARACTERISTIC 1 SYSTEM WITH RESISTIVE LOADS ONLY NEXT SLIDE

Sarath Chandrasiri / EPD / MEW THE SLOPE OF THE SYSTEM LOAD CHARACTERISTIC DEPENDS ON THE NATURE OF CONSUMER LOADS

Sarath Chandrasiri / EPD / MEW ROTATING LOADS TEND TO MAKE THE SLOPE GREATER RESISTIVE LOADS TEND TO MAKE THE SLOPE LESS

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (f) SYSTEM LOAD CHARACTERISTIC POWER (MW) MORE ROTATING LOADS LESS ROTATING LOADS

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (f) f Hz SYSTEM LOAD CHARACTERISTIC GENERATOR CHARACTERISTIC POWER (MW)

Sarath Chandrasiri / EPD / MEW POINT OF INTERSECTION OF SYSTEM & GENERATION CHARACTERISTICS (UNDER STEADY STATE) ACTUAL POINT OF OPERATION OF GENERATOR/S

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (Hz) SYSTEM LOAD CHARACTERISTIC GOV CHARACTERISTIC WITH DROOP POWER (MW) POINT OF INTERSECTION

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (Hz) 50 MACHINE LOAD (MW) 35 OPERATING POINT

Sarath Chandrasiri / EPD / MEW FOR STEADY STATE & SLOW VARIATIONS THESE TWO POINTS COINCIDE FOR RAPID VARIATIONS THEY ARE GENERALLY NOT THE SAME.

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (Hz) 50 SYSTEM LOAD CURVE GOV CHACTERISTIC WITH DROOP Δf (WITH DROOP) 49.9 POWER (MW) 35 DEMO FOR SLOW VARIATIONS THE POINT OF OPERATION REMAINS AT THE POINT OF INTERSECTION NEXT SLIDE

Sarath Chandrasiri / EPD / MEW SLOW VARIATION EXAMPLE

Sarath Chandrasiri / EPD / MEW ACTUAL INCIDENT 17/02/2000 HIDD MACHINES TRIP ON GAS STATION PROBLEM

Sarath Chandrasiri / EPD / MEW E EEE HIDD MACHINES START Protective Load Shedding HIDDCB‘s OPEN DEMO LOAD OF RPS GT6

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (Hz) 50 OVERALL GEN CHARACTER HPWS 11 POWER (MW) DEMO GT NEXT SLIDE

Sarath Chandrasiri / EPD / MEW DYNAMIC RESPONSE OF THE GOVERNOR

Sarath Chandrasiri / EPD / MEW DYNAMIC RESPONSE GIVES THE RESPONSE FOR VARIATIONS RAPI D

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (Hz) SYSTEM LOAD CURVE GOV CHARACTERISTIC WITH DROOP POWER (MW) 35 DEMO FOR RAPID VARIATIONS THE POINT OF OPERATION TEMPORARILY GOES AWAY FROM THE POINT OF INTERSECTION NEXT SLIDE

Sarath Chandrasiri / EPD / MEW LET US PLAY THAT IN SLOW MOTION

Sarath Chandrasiri / EPD / MEW SYSTEM FREQUENCY (Hz) SYSTEM LOAD CURVE GOV CHARACTERISTIC WITH DROOP POWER (MW) 35 DEMO 1 2 NEXT SLIDE

Sarath Chandrasiri / EPD / MEW FOR SLOW OR RAPID VARIATIONS THE STARTING POINT (1) THE FINAL POINT (2) ARE THE SAME THE DIFFERENCE IS IN THE LOCUS

Sarath Chandrasiri / EPD / MEW MAGNITUDE OF THE FINAL RESPONSE DEPENDS ON TWO FACTORS 1) DROOP OF GOVERNOR 2) SLOPE OF THE SYSTEM CHARACTERISTIC

Sarath Chandrasiri / EPD / MEW DYNAMIC RESPONSE PARAMETERS DECIDE HOW QUICKLY THIS RESPONSE WILL COME

Sarath Chandrasiri / EPD / MEW SOME EXAMPLES OF RAPID CHANGES

Sarath Chandrasiri / EPD / MEW SUDDEN SWITCHING ON OF A LOADED FEEDER

Sarath Chandrasiri / EPD / MEW GENERATOR LOAD 2 LOAD KW 200 KW

Sarath Chandrasiri / EPD / MEW POWER (MW) SYSTEM FREQ (Hz) GENERATION SYSTEM 49.5 AUTOMATIC RESPONSE OF GOVERNOR DUE TO DROOP 1313 MANUAL ACTION DEMO NEXT SLIDE

Sarath Chandrasiri / EPD / MEW POWER (MW) SYSTEM FREQ (Hz) GENERATION SYSTEM 49.5 PRIMARY RESPONSE 1313 SECONDARY RESPONSE DEMO NEXT SLIDE

Sarath Chandrasiri / EPD / MEW GENERATOR TRIP ILLUSTRATED USING THE 2 MACHINE EXAMPLE

Sarath Chandrasiri / EPD / MEW MACHINE LOAD (MW) SYSTEM FREQ (Hz) G1 G2 OVERALL SYSTEM G1 = 10 MW G2 = 15 MW TOT = 25 MW F= 50 Hz G1 = 10 MW G2 = 15 MW TOT = 25 MW F= 50 Hz G1 = 0 MW G2 = 25 MW TOT = 25 MW F= 50 Hz G1 = 0 MW G2 = 22 MW TOT = 22 MW F= Hz``` DEMO NEXT SLIDE

Sarath Chandrasiri / EPD / MEW AN ANALOGY TO ILLUSTRATE THE ROLE PLAYED BY KINETIC ENERGY

Sarath Chandrasiri / EPD / MEW WATER TANK LEVEL TRANSMITTER LEVEL CONTROL VALVE CONTROL SIGNAL PUMP NOMINAL WATER LEVEL LOW LEVEL PROTECTION OUTFLOW INFLOW +1M -1M NEXT SLIDE

Sarath Chandrasiri / EPD / MEW TANK LEVEL (M)VALVE OPENING (%) NOMINAL TANK LEVEL (M)VALVE OPENING (%) NOMINAL

Sarath Chandrasiri / EPD / MEW WATER TANK LEVEL TRANSMITTER LEVEL CONTROL VALVE CONTROL SIGNAL PUMP NOMINAL WATER LEVEL LOW LEVEL PROTECTION OUTFLOW INFLOW +1M -1M VALVE OPENING

Sarath Chandrasiri / EPD / MEW WATER TANK LEVEL TRANSMITTER LEVEL CONTROL VALVE CONTROL SIGNAL PUMP NOMINAL WATER LEVEL LOW LEVEL PROTECTION OUTFLOW INFLOW +1M -1M

Sarath Chandrasiri / EPD / MEW MECHANICAL POWER INPUT (DEPENDS ON FUEL CV OPENING) ELECTRICAL POWER OUTPUT KINETIC ENERGY STORED IN THE ROTOR ½ I ω 2 GENERATOR POWER BALANCE POWER DUE TO KE CHANGE I ωώ

Sarath Chandrasiri / EPD / MEW MECHANICAL POWER OUTPUT OF THE TURBINE IS UNABLE TO KEEP UP WITH THE GENERATOR POWER OUTPUT UNDER TRANSIENT CONDITIONS.

Sarath Chandrasiri / EPD / MEW GENERATOR POWER OUTPUT CHANGES INSTANTANEOUSLY SYSTEM FREQUENCY CHANGES GRADUALLY DUE TO INERTIA

Sarath Chandrasiri / EPD / MEW GOVERNOR LOOKS AT THE SYSTEM FREQUENCY ONLY GOVERNOR OUTPUT SIGNAL CHANGES WITH FREQUENCY ONLY

Sarath Chandrasiri / EPD / MEW GOVERNOR OUTPUT SIGNAL IS FURTHER RESTRICTED BY THE FOLLOWING: 1.AMPLITUDE LIMITATIONS 2.GRADIENT LIMITATIONS 3.DEAD BANDS

Sarath Chandrasiri / EPD / MEW TRANSPORT DELAYS COMBUSTION/HEAT TRANSFER DELAYS MECHANICAL INERTIA

Sarath Chandrasiri / EPD / MEW AS A RESULT OF ALL THIS PePe P mech MECHANICAL POWER LAGS BEHIND ELECTRICAL POWER

Sarath Chandrasiri / EPD / MEW ANALYSIS OF THE KINETIC ENERGY CONTRIBUTION

Sarath Chandrasiri / EPD / MEW KE = ½ I ω 2 Where, I = Moment of Inertia of GT Rotor ω = Rotational Speed in radians/sec f 0 = Rated frequency (50 Hz) KE 0 = KE (½ I ω 0 2 = ½ I(2π f 0 ) 2 ) of the Rotor at f 0 in MWs P n = Power Rating of the Machine in MW H= KE 0 /P n

Sarath Chandrasiri / EPD / MEW THE ADVANTAGE OF USING H IS THAT IT IS ESSENTIALLY INDEPENDENT OF THE GENERATOR SIZE Normal Range of H: 2 to 8 seconds

Sarath Chandrasiri / EPD / MEW H CAN ALSO BE DEFINED FOR THE WHOLE SYSTEM

Sarath Chandrasiri / EPD / MEW H is directly proportional to I A High Inertia Rotor has a High H and Vice Versa

Sarath Chandrasiri / EPD / MEW PRIMARY RESPONSE INITIAL RESPONSE PRIMARY RESPONSE INITIAL RESPONSE PRIMARY RESPONSE

Sarath Chandrasiri / EPD / MEW Equation for Rate of Freq Fall If, ΔP= Load Increase (pu) f 0 = Rated Frequency (Hz) f = Actual Frequency (Hz) Then the rate of drop of freq (df/dt) 0 immediately after the fault is given by: (df/dt) 0 = ΔPf 0 /2H

Sarath Chandrasiri / EPD / MEW (df/dt) 0 = ΔPf 0 /2H Thus, Rate of drop frequency will be higher With, Higher ΔP Lower H

Sarath Chandrasiri / EPD / MEW THEREFORE A HIGH H - Constant IS DESIRABLE

Sarath Chandrasiri / EPD / MEW INITIAL RESPONSE PRIMARY RESPONSE SECONDARY RESPONSE TERTIARY (OR FINAL) RESPONSE

Sarath Chandrasiri / EPD / MEW INITIAL RESPONSE COMES FROM THE KINETIC ENERGY OF THE ROTOR. GOVERNOR IS NOT INVOLVED. NATURAL PROCESSES ARE IN CONTROL HERE

Sarath Chandrasiri / EPD / MEW PRIMARY RESPONSE DUE TO GOVERNOR ACTION. AUTOMATIC SYSTEMS ARE IN CONTROL SYSTEM FREQUENCY IS STILL NOT AT THE RATED VALUE AT THE END OF STAGE.

Sarath Chandrasiri / EPD / MEW SECONDARY RESPONSE MANUAL ACTION BY OPERATORS OR ALFC (AUTOMATIC LOAD FREQUENCY CONTROLLER). SYSTEM SPINNING RESERVE STILL NOT RESTORED AT THE END OF THIS STAGE. TERTIARY RESPONSE NORMALIZATION OF THE SYSTEM TO PRE FAULT CONDITIONS SPINNING RESERVE NORMALIZED. Ex. Put back tripped unit or replace it by another

Sarath Chandrasiri / EPD / MEW PRIMARY RESPONSE INITIAL RESPONSE PRIMARY RESPONSE INITIAL RESPONSE PRIMARY RESPONSE

Sarath Chandrasiri / EPD / MEW DYNAMIC FREQUENCY DEVIATION SHOULD BE ABOVE UFLS STAGE 1 SETTING (49.3 Hz) QUASI STEADY STATE FREQUENCY DEVIATION SHOULD BE ABOVE UFLS STAGE 7 SETTING (49.5 Hz) DYNAMIC FREQUENCY DEVIATION SHOULD BE ABOVE UFLS STAGE 1 SETTING (49.3 Hz) QUASI STEADY STATE FREQUENCY DEVIATION SHOULD BE ABOVE UFLS STAGE 7 SETTING (49.5 Hz)

Sarath Chandrasiri / EPD / MEW FACTORS AFFECTING DYNAMIC FREQ DEVIATIONS

Sarath Chandrasiri / EPD / MEW The Dynamic Frequency Deviation will be more with: Higher P (pu Loss of Generation) Lower H of System + Generators Larger Governor Droop Inhibiting the Governor Response by:  Larger Dead Bands  Limited Gradient of Governor of Response  Absence of Step Response of Governors

Sarath Chandrasiri / EPD / MEW 1 TIME (SEC) SYS FREQ (Hz) LOAD (MW) MW (STEP OUTPUT) DISTURBANCE OCCURS SIEMENS - RPS

Sarath Chandrasiri / EPD / MEW 1 TIME (SEC) SYS FREQ (Hz) LOAD (MW) STEP INCREASE = 10 MW 5 MW (RAMP OUTPUT) 4.5 SEC DISTURBANCE OCCURS GRADIENT=66 MW/MIN 49.3 DEMO ABB - RPS

Sarath Chandrasiri / EPD / MEW 1 TIME (SEC) SYS FREQ (Hz) LOAD (MW) MW (RAMP OUTPUT) 4 SEC DISTURBANCE OCCURS GRADIENT=2.5 MW/SEC AL EZZEL (TYPICAL) GRADIENT=0.5 MW/SEC

Sarath Chandrasiri / EPD / MEW 1 TIME (SEC) SYS FREQ (Hz) LOAD (MW) SEC DISTURBANCE OCCURS AL EZZEL (TYPICAL)

Sarath Chandrasiri / EPD / MEW 1 TIME (SEC) SYS FREQ (Hz) LOAD (MW) DISTURBANCE OCCURS GRADIENT=2 MW/SEC HIDD (TYPICAL)

Sarath Chandrasiri / EPD / MEW

GRID CODES DEFINE GOVERNOR RESPONSE REQUIREMENTS MAGNITUDE OF RESPONSE SPEED OF RESPONSE

Sarath Chandrasiri / EPD / MEW EXAMPLES: Note: Pn – Rated Load MALAYSIA - 5% of Pn in 2 sec, 10% of Pn in 3 sec. AUSTRALIA - 4% of Pn in 2.5 sec, 20% OF Pn in 10 sec. UK – 12 % of Pn in 10 sec.

Sarath Chandrasiri / EPD / MEW THE REQUIREMENT IS BASED ON THE RATIO OF HIGHEST CAPACITY GENERATING UNIT TO THE SYSTEM CAPACITY

Sarath Chandrasiri / EPD / MEW THIS RATIO IS AS FOLLOWS: MALAYSIA – MORE THAN 10% AUSTRALIA & UK - 5%

Sarath Chandrasiri / EPD / MEW THE SITUATION IS SIMILAR OR EVEN WORSE THAN MALAYSIA. (i.e.) RATIO OF LARGEST UNIT TO TOTAL SYSTEM CAPACITY IS MORE THAN 10%. IT IS STILL HIGHER IN WINTER

Sarath Chandrasiri / EPD / MEW TO REDUCE COST OF MACHINES TO SAFEGUARD MACHINES FROM STRESS DUE TO SYSTEM EMERGENCIES

Sarath Chandrasiri / EPD / MEW REDUCE GOVERNOR RESPONSE SPEED PUT LIMITS ON RESPONSE SIZE PUT LIMITS ON RESPONSE GRADIENT HAVE LARGE DEAD BANDS HAVE HIGH DROOP SETTINGS

Sarath Chandrasiri / EPD / MEW LOW H- CONSTANT (1SEC OR BELOW) LOW SHORT CIRCUIT RATIO (SCR) LOW SYNCHRONOUS REACTANCE LOW PF RATING (0.95 agst 0.8)

Sarath Chandrasiri / EPD / MEW Using Conservative Settings for:  Over Excitation Limiter  Under Excitation Limiter Using Non Adaptive Settings for  Stator Current Limiter  Rotor Current Limiter

Sarath Chandrasiri / EPD / MEW STUDY EFFECT OF AEPC GOVERNORS STUDY EFFECT OF ABB REHABILITATION ON GOVERNORS FUTURE PLAN FOR IMPROVING GOVERNOR RESPONSE OF AEPC

Sarath Chandrasiri / EPD / MEW PARTIAL OR FULL BLACKOUTS ARE INEVITABLE

Sarath Chandrasiri / EPD / MEW CONCENTRATE ON RESTORATION PROCEDURES

Sarath Chandrasiri / EPD / MEW STEP-GRADIENT LIMITERS

Sarath Chandrasiri / EPD / MEW STEP SIZE IS LIMITED TO 15 MW

Sarath Chandrasiri / EPD / MEW THIS LIMIT APPLIES BOTH FOR SLOW & FAST VARIATIONS OF FREQUENCY

Sarath Chandrasiri / EPD / MEW ABB STEP-GRADIENT LIMITERS

Sarath Chandrasiri / EPD / MEW REQUIRED LOAD GRADIENT CONTROLLER ACTUAL LOAD SET POINT - + LOAD/FREQ CONTROLLER ACTUAL LOAD FREQ CONTROLLE R + - ACTUAL FREQ 50 Hz STEP GRADIEN T LIMITER + -

Sarath Chandrasiri / EPD / MEW DOES NOT AFFECT THE RESPONSE OF GOVERNOR FOR SLOW VARIATIONS OF SYSTEM FREQUENCY

Sarath Chandrasiri / EPD / MEW AFFECTS THE RESPONSE OF GOVERNOR FOR RAPID VARIATIONS OF SYSTEM FREQUENCY

Sarath Chandrasiri / EPD / MEW STEP SIZE IS LIMITED TO 10 MW GRADIENT IS LIMITED TO 1.1 MW/SEC

Sarath Chandrasiri / EPD / MEW

THESE CANNOT CHANGE SUDDENLY AS ENERGY IS ASSOCIATED WITH THEM. ENERGY CANNOT BE INCREASED OR DECREASED SUDDENLY!

Sarath Chandrasiri / EPD / MEW PARAMETERS THAT CANNOT UNDERGO STEP CHANGES ARE VERY USEFUL FOR ANALYZING DISTURBANCES

Sarath Chandrasiri / EPD / MEW