Post on 13-Dec-2015
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PRESENTATION PRESENTATION ON REACTIVE ON REACTIVE
POWER CONTROLPOWER CONTROL
S.K.SOONEES.K.SOONEE
GM,SRLDCGM,SRLDC
BANGALOREBANGALORE
POWER IS PLEASURE---ASK POWER IS PLEASURE---ASK THOSE WHO ARE SEEKING ITTHOSE WHO ARE SEEKING IT
POWER IS PAIN ---ASK POWER IS PAIN ---ASK THOSE WHO HAVE ITTHOSE WHO HAVE IT
REAL POWER IS PAIN REAL POWER IS PAIN IMAGINARY POWER IMAGINARY POWER PLEASUREPLEASURE
SOURCES OF REACTIVE SOURCES OF REACTIVE POWERPOWER
SYNCHRONOUS GENERATORSSYNCHRONOUS GENERATORS SYNCHRONOUS CONDENSORSSYNCHRONOUS CONDENSORS SHUNT CAPACITORSSHUNT CAPACITORS STATIC THYRISTOR BASED STATIC THYRISTOR BASED
DEVICESDEVICES TRANSMISSION LINESTRANSMISSION LINES
REACTIVE POWER REACTIVE POWER SINKSSINKS
LOADSLOADS INDUCTION MOTORS(PUMPS,FANS ETC)INDUCTION MOTORS(PUMPS,FANS ETC) INDUCTIVE LOADS (CHOKES ETC)INDUCTIVE LOADS (CHOKES ETC)
TRANSFORMERSTRANSFORMERS TRANSMISSION LINESTRANSMISSION LINES REACTORSREACTORS STATIC THYRISTOR BASED DEVICESSTATIC THYRISTOR BASED DEVICES SHYNCHRONOUS MACHINESSHYNCHRONOUS MACHINES
SYNCHRONOUSSYNCHRONOUSMACHINESMACHINES
SYNCHRONOUS MACHINESYNCHRONOUS MACHINEMODES OF OPERATIONMODES OF OPERATION
UNDER-EXCITED OR LEADING PFUNDER-EXCITED OR LEADING PF CONSUMES REACTIVE POWERCONSUMES REACTIVE POWER
OVER-EXCITED OR LAGGING PFOVER-EXCITED OR LAGGING PF PRODUCES REACTIVE POWERPRODUCES REACTIVE POWER
SYNCHRONOUS SYNCHRONOUS GENERATORSGENERATORS
VECTOR DIAGRAMVECTOR DIAGRAME
I
θ
δ
V
jIXd
Iθδ
V
jIXd
E
OVER-EXCITED
UNDER-EXCITED
CAPABILITY CURVECAPABILITY CURVE
U2=P2+Q2
LEAD
LAG
MOTORING GENERATING
Q=MVAR, REACTIVE POWER
P=MW, ACTIVE POWER
LIMITATIONSLIMITATIONSLA
G/O
VE
R E
XC
ITE
D(+
)LE
AD
/UN
DE
R E
XC
ITE
D(+
)
TRANSMISSION TRANSMISSION LINESLINES
TRANSMISSION LINESTRANSMISSION LINESSILSIL
SURGE IMPEDANCE LOADING:-The SIL SURGE IMPEDANCE LOADING:-The SIL is the loading level where the reactive is the loading level where the reactive VARs generated by the line capacitance VARs generated by the line capacitance equal the VARs required by the line equal the VARs required by the line inductance. inductance.
QUICK FACT:QUICK FACT: 100 KM OF 400 KV LINE(MOOSE) CAUSES 100 KM OF 400 KV LINE(MOOSE) CAUSES
55 MVAR OF CHARGING CURRENT55 MVAR OF CHARGING CURRENT
OVERVOLTAGE OVERVOLTAGE PROBLEMSPROBLEMS
Generator self-excitationGenerator self-excitation Insulation breakdownInsulation breakdown FlashoverFlashover Customer equipment damageCustomer equipment damage Excessive heating of overexcited Excessive heating of overexcited
transformerstransformers
UNDERVOLTAGE CAUSESUNDERVOLTAGE CAUSES
Heavy line loadingHeavy line loading DisturbancesDisturbances High customer demandHigh customer demand Induction motor heatingInduction motor heating Dim lights - more lightsDim lights - more lights Less heat - more heatersLess heat - more heaters Voltage collapseVoltage collapse
SOME FACTSSOME FACTS
A 10 percent voltage drop cuts light A 10 percent voltage drop cuts light output by 30 percent. output by 30 percent.
A 10 percent voltage drop cuts heat A 10 percent voltage drop cuts heat output by 20 percent. The user output by 20 percent. The user response, in many such cases, is to response, in many such cases, is to turn on more lightsturn on more lights
TO CORRECT LOW TO CORRECT LOW VOLTAGEVOLTAGE
Remove shunt ReactorsRemove shunt Reactors Insert shunt capacitorsInsert shunt capacitors Energize open linesEnergize open lines Raise LTC set pointsRaise LTC set points Raise voltage regulator set pointsRaise voltage regulator set points Use generator reactive overload Use generator reactive overload
capabilitycapability Curtail interruptible loadsCurtail interruptible loads Shed firm loadShed firm load
TO CORRECT HIGH TO CORRECT HIGH VOLTAGEVOLTAGE
Remove shunt capacitorsRemove shunt capacitors Insert shunt reactorsInsert shunt reactors Lower voltage set pointsLower voltage set points Close open-ended lines or remove Close open-ended lines or remove
from service altogetherfrom service altogether Buck with generatorsBuck with generators Remove transmission lines from Remove transmission lines from
serviceservice
POINTS TO REMEMBERPOINTS TO REMEMBER
VAR control is the key to voltage VAR control is the key to voltage controlcontrol
Use voltage control equipment Use voltage control equipment earlyearly
Avoid voltage collapse/High Avoid voltage collapse/High Voltage by smart operatingVoltage by smart operating
Permissible Voltage LimitsPermissible Voltage Limits
Voltage Under NormalCondition
Max permissible Voltageat the far end of lines
normally kept energizedfrom one end
Nominal(kV)
Max Min kV
132 145 120 148
220
400
735/765
245
420
800
200
360
700
245
420
800
REQUIREMENTS & REQUIREMENTS & METHODSMETHODS
LOAD ANGLELOAD ANGLE
ITS IMPLICATION IN ITS IMPLICATION IN POWER SYSTEM POWER SYSTEM
OPERATIONOPERATION
LOAD ANGLELOAD ANGLE
VOLTAGEVOLTAGEvsvs
FREQUENCYFREQUENCY
Frequency and VoltageFrequency and Voltage
““The general synchronous machine The general synchronous machine equations show that voltage levels equations show that voltage levels are directly proportional to the are directly proportional to the frequency and for godd voltage frequency and for godd voltage control extremes of system control extremes of system frequency are to be avoided”frequency are to be avoided”
………………Excerpts from Chapter on Excerpts from Chapter on Reactive Power and Voltage control. Reactive Power and Voltage control. System operators Manual LSystem operators Manual L
Impact of freq on Impact of freq on VoltageVoltage
E=4.44E=4.44ффfNfNWhere E is the EMF Where E is the EMF Generated,f is the Generated,f is the Frequency, Frequency, фф the flux the flux
Transmission Planning Transmission Planning criteriacriteria
1. P=P1. P=P00(F/F(F/F
00))
2. Q=Q2. Q=Q00(V/V(V/V
00))22
IEEE MODEL: COMPOSITE IEEE MODEL: COMPOSITE LOADSLOADS
P(V,F)=(A1Vn1Fm1+A2Vn2fm2+A3Vn3Fm3)P0
Q(V,F)=(A4Vn4Fm4+A5Vn5Fm5+A6Vn6Fm6)Q0
CO-EFFICIENTS A1 TO A6 ARE ASSOCIATED WITH LOAD CATEGORIES
A1+A2+A3=1
A4+A5+A6=1
LOAD LOAD REPRESENTATIONREPRESENTATION
TYPE OF TYPE OF LOADLOAD
PFPF ∆∆P/∆VP/∆V
(%)(%)∆∆P/∆FP/∆F
(%)(%)∆∆Q/∆VQ/∆V
(%)(%)∆∆Q/∆FQ/∆F
(%)(%)INCANDESENT LAMPINCANDESENT LAMP
11 1.61.6 00 00 00FLOURESCENT LAMPFLOURESCENT LAMP
1.001.00 11 11 4646 -65-65AIR CONDITIONER AIR CONDITIONER WINDOW TYPEWINDOW TYPE 0.820.82 0.50.5 0.60.6 2.52.5 -2.8-2.8REFRIGERATORREFRIGERATOR
0.790.79 0.80.8 0.50.5 2.52.5 -1.3-1.3HOME APPLIANCE WITH HOME APPLIANCE WITH MOTORMOTOR 0.30.3 0.10.1 1.81.8 -1.6-1.6150 HP INDUCTION 150 HP INDUCTION MOTORMOTOR 0.880.88 -0.1-0.1 1.11.1LARGE US TOWNLARGE US TOWN
0.890.89 1.71.7 1.91.9 33ALUMINIUM PLANTALUMINIUM PLANT
0.910.91 2.42.4 0.40.4 1.61.6 0.70.7AGRICULTURAL IN AGRICULTURAL IN WINTER(US)WINTER(US) 0.80.8
TRANSFORMERSTRANSFORMERSAND AND
TAP CHANGINGTAP CHANGING
ICT TAPSICT TAPS
400 KV SIDE
220 KV SIDE TAP NO 17=360/220
TAP NO 1=440/220
VV
ON LOAD TAP CHANGER
1.25% OR 5 KV PER TAP±10% RANGE
NOMINAL TAP AT 9
ICT TAP CHANGING ICT TAP CHANGING EXAMPLEEXAMPLE
400 KV
210 KV TAP NO 17=360/220
TAP NO 1=440/220
VV
BASE CONDITION
9
100 MW
50 MVAR
ICT TAP CHANGING ICT TAP CHANGING EXAMPLEEXAMPLE
408 KV
208 KV TAP NO 17=360/220
TAP NO 1=440/220
VV
TAP IS MOVED FROM 9 TO 3 SAY
MVAR FLOW AND RESULTANT VOLTAGES ARE DEPENDANT ON GRID AND STRENGTH OF BUS
3100 MW
10 MVAR
TAP CHANGINGTAP CHANGING
REARRANGES MVAR FLOWREARRANGES MVAR FLOW TO BE DONE CONSIDERING TO BE DONE CONSIDERING
VOLTAGES ON BOTH SIDESVOLTAGES ON BOTH SIDES CO-ORDINATED ACROSS THE CO-ORDINATED ACROSS THE
SYSTEMSYSTEM TAP CHANGING SCHEDULESTAP CHANGING SCHEDULES
GT TAP CHANGINGGT TAP CHANGING
~ INFINITE BUS
400 KV
21 KVTAP 9
500 MW
30 MVAR
BASE CASE
~ INFINITE BUS
400 KV
21.3 KVTAP 12
500 MW
5 MVAR
TAP CHANGED
REACTIVE LOAD STRATAREACTIVE LOAD STRATA
LEADING
LAGGING
LOAD
TRANSFORMERS
LOADED LINES
REACTORS
CAPACITORS
LIGHTLY LOADED LINES
DURATION
LOAD SHEDDING
BASE LOAD MET BY
1. CAPACITORS
2. GENERATORS /LINES BELOW SIL SUPPLYING VAR
REACTORS REMOVAL
1.SWITCH OFF CAPACITORS
2.GENERATORS ABSORBING VARS
3.SWITCH OFF LIGHTLY LOADED LINES
4.TAP STAGGERING
VOLTAGE VOLTAGE CONTROLCONTROL
WHAT THE IEGC SAYS……..WHAT THE IEGC SAYS……..
IEGC SECTION 4.9IEGC SECTION 4.9
4.94.9 Reactive Power CompensationReactive Power Compensation (a)(a) Reactive Power compensation Reactive Power compensation
and/or other facilities, should be and/or other facilities, should be provided by SEBs/STUs or distributing provided by SEBs/STUs or distributing agencies as far as possible in the low agencies as far as possible in the low voltage systems close to the load points voltage systems close to the load points thereby avoiding the need for exchange thereby avoiding the need for exchange of Reactive Power to/from ISTS and to of Reactive Power to/from ISTS and to maintain ISTS voltage within the maintain ISTS voltage within the specified range.specified range.
IEGC SECTION 6.9IEGC SECTION 6.9 6.9 (6.9 (J)All generating units shall normally have their J)All generating units shall normally have their
automatic voltage regulators (AVRs) in operation, automatic voltage regulators (AVRs) in operation, with appropriate settings.with appropriate settings. In particular, if a In particular, if a generating unit of over fifty (50) MW (10 MW in generating unit of over fifty (50) MW (10 MW in case of North-Eastern region) size is required to be case of North-Eastern region) size is required to be operated without its AVR in service, the RLDC shall operated without its AVR in service, the RLDC shall be immediately intimated about the reason and be immediately intimated about the reason and duration, and its permission obtained. Power duration, and its permission obtained. Power System Stabilisers (PSS) in AVRs of generating System Stabilisers (PSS) in AVRs of generating units (wherever provided), shall be properly tuned units (wherever provided), shall be properly tuned as per a plan prepared for the purpose by the CTU as per a plan prepared for the purpose by the CTU from time to time. CTU will be allowed to carry out from time to time. CTU will be allowed to carry out tuning/checking of PSS wherever considered tuning/checking of PSS wherever considered necessary.necessary.
IEGC SECTION 6.9IEGC SECTION 6.9
(q)(q) All regional constituents shall All regional constituents shall make all possible efforts to ensure make all possible efforts to ensure that the grid voltage always remains that the grid voltage always remains within the following operating within the following operating range.range.
NOMINANOMINALL
MAXIMUMAXIMUMM
MINIMUMINIMUMM
400400 420420 360360
220220 245245 200200
132132 145145 120120
IEGC SECTION 6.4IEGC SECTION 6.4
6.46.4 Demand ControlDemand Control 6.4.16.4.1 Introduction:Introduction: This section is concerned with the provisions This section is concerned with the provisions
to be made by SLDC's to permit the reduction to be made by SLDC's to permit the reduction of demand in the event of insufficient of demand in the event of insufficient generating capacity, and transfers from generating capacity, and transfers from external interconnections being not available external interconnections being not available to meet demand, to meet demand, or in the event of breakdown or in the event of breakdown or operating problems (such as frequency, or operating problems (such as frequency, voltage levels or thermal overloads) on any voltage levels or thermal overloads) on any part of the grid.part of the grid.
IEGC SECTION 6.8IEGC SECTION 6.8
6.86.8 Recovery ProceduresRecovery Procedures d)The RLDC is authorised during d)The RLDC is authorised during
the restoration process following a the restoration process following a black out, to operate with reduced black out, to operate with reduced security standards for voltage and security standards for voltage and frequency as necessary in order to frequency as necessary in order to achieve the fastest possible recovery achieve the fastest possible recovery of the grid.of the grid.
IEGC SECTION 7.6IEGC SECTION 7.6 7.67.6 Reactive Power and Voltage Control:Reactive Power and Voltage Control:1.1. The Beneficiaries are expected to provide local VAR The Beneficiaries are expected to provide local VAR
compensation/generation such that they do not draw VARs from compensation/generation such that they do not draw VARs from the EHV grid.the EHV grid. However, considering the present limitations, this However, considering the present limitations, this is not being insisted upon. Instead, VAR drawals by Beneficiaries is not being insisted upon. Instead, VAR drawals by Beneficiaries (except on their lines emanating from ISGS) are to be priced as (except on their lines emanating from ISGS) are to be priced as follows:-follows:-
-- The Beneficiary pays for VAR drawal when voltage at the The Beneficiary pays for VAR drawal when voltage at the metering point is below 97%.metering point is below 97%.
-- The Beneficiary gets paid for VAR return when voltage is below The Beneficiary gets paid for VAR return when voltage is below 97%.97%.
-- The Beneficiary gets paid for VAR drawal when voltage is above The Beneficiary gets paid for VAR drawal when voltage is above 103%.103%.
-- The Beneficiary pays for VAR return when voltage is above The Beneficiary pays for VAR return when voltage is above 103%.103%.
2.2. The charge/payment for VARs, shall be at a nominal paise/kVARh The charge/payment for VARs, shall be at a nominal paise/kVARh rate as may be approved by CERC from time to time, and will be rate as may be approved by CERC from time to time, and will be between the beneficiary and the Pool Account (for VAR between the beneficiary and the Pool Account (for VAR interchanges with ISTS), and between two beneficiaries (for VAR interchanges with ISTS), and between two beneficiaries (for VAR interchanges on ties between their systems).interchanges on ties between their systems).
3.3. Notwithstanding the above, RLDC may direct a beneficiary to Notwithstanding the above, RLDC may direct a beneficiary to curtail its VAR drawal/injection in case the security of grid or curtail its VAR drawal/injection in case the security of grid or safety of any equipment is endangered.safety of any equipment is endangered.
IEGC SECTION 7.6 IEGC SECTION 7.6 CONTD….CONTD….
7.6.4In general, the Beneficiaries shall endeavour to 7.6.4In general, the Beneficiaries shall endeavour to minimise the VAR drawalminimise the VAR drawal at an interchange point when at an interchange point when the voltage at that point is below 95% of rated, and shall the voltage at that point is below 95% of rated, and shall not return VARs when the voltage is above 105%. ICT not return VARs when the voltage is above 105%. ICT taps at the respective drawals points may be changed to taps at the respective drawals points may be changed to control the VAR interchange as per a beneficiary's control the VAR interchange as per a beneficiary's request to the RLDC, but only at reasonable intervals.request to the RLDC, but only at reasonable intervals.
5.5. Switching in/out of all 400 KV bus and line Switching in/out of all 400 KV bus and line Reactors throughout the grid shall be carried out as per Reactors throughout the grid shall be carried out as per instructions of RLDC. instructions of RLDC. Tap changing on all 400/220 KV Tap changing on all 400/220 KV ICTs shall also be done as per RLDC's instructions only.ICTs shall also be done as per RLDC's instructions only.
6.6. The ISGS shall generate/absorb reactive power as The ISGS shall generate/absorb reactive power as per instructions of RLDCper instructions of RLDC, within capability limits of the , within capability limits of the respective generating units, that is without sacrificing on respective generating units, that is without sacrificing on the active generation required at that time. No payments the active generation required at that time. No payments shall be made to the generating companies for such VAR shall be made to the generating companies for such VAR generation/absorption. generation/absorption.
VA MeteringVA Metering
VAVA METERING METERING ACCURACY CLASS ACCURACY CLASS DIFFICULTY IN CALIBRATION AND DIFFICULTY IN CALIBRATION AND
CHECKINGCHECKING DIFFICULTY IN MEASURING BAD DIFFICULTY IN MEASURING BAD
POWER FACTORPOWER FACTOR