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Reactive Power Management

- Case study

-- Nandan Pathak (AE)

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ICT -1 ICT -2 G-3 G-4 G-5

200 MW160 MVAR

160 MW135 MVAR200 MW

160 MVAR

160 MW135 MVAR

160 MW140 MVAR

LOAD LOAD

220 kVGirwali Bus

220 kV ParliBus

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~

GENERATION

870 MW

730 MVAR

LOAD:

A ) GENERATORS:a) High MVAR drawl

b) High excitation currentB) ICT:

a) Overloading due to MVARb) Low voltage on 220 kV bus ( 200 kV)

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C) LOAD:11 kV side:

a) Overload trippingb) Very low voltagesc) Conductor snappingd) Local load shedding

440 V side:

a) Failure of transformersb) Conductor snapping

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A)High seasonal load especially agriculture

during October to March

B) Failure of reactive compensation

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A) Identification of areas

a) Beed districtb) Solapur districtc) Nanded district

d) Pabhani districte) Latur district

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A) Identification of radial feeders

220 kVGirwali Bus

220 kV Nanded160 MW 100 MVAR

220 kV Parbhani100 MW 80 MVAR 132 kV Parli

Bus

132kV Beed80 MW 60 MVAR

~ ~

132 kV Latur -190 MW 75 MVAR

132 kV Latur -260 MW 45 MVAR

132 kVGirwali Bus

On similar lines loaded 11 & 33 feeders were identified.

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I) Reactive power compensation available :i. Substation ----- 164 MVAR

ii. Switched capacitors on 11kV 240 MVAR (0.6 X405)II) Focus Area 11 kV , 0.6 MVAR capacitors

a. Repairs in a central laboratoryb. On site replacement, checking, modification, training

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Modifications adopted foroptimum compensation

1. Cell rating 0.66 Mvar at 12 kV

2. De-rating at Low Voltage

3. Modification

A. Fixed capacitors

B. Addition to basic scheme

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4. On site demonstrations

5. Team visit Nasik , Pune (R ),Kolhapur, Sangli,Parbhani

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1. Reduction in overload tripping of 11 kV &

33 kV feeders. 2. Reduction in blowing of HG fuses at 33/11

kV transformers.

3. Reduction in conductor snapping.

4. Improvement in voltage profiles

LT 105 Volts to 190 volts

11kV 7.6 kV to 9.8 kV

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ICT -1 ICT -2 G-3 G-4 G-5

250 MW (200)100 MVAR(160)

200 MW(160)60 MVAR(135)250 MW(200)

100MVAR(160)

200 MW60 MVAR

195 MW(150)80 MVAR(140)

LOAD LOAD

220 kVGirwali Bus

220 kV ParliBus

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~

GENERATION

1095 MW (870)

400 MVAR (730)

LOAD:

Voltage changes:220 kV 215 kV (200 kV)

132 kV 125 kV (106 kV)33 kV 31 kV (27 kV)

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Radial load changes

132 kVParli Bus

132kV Beed95 MW 30 MVAR(80 MW 60 MVAR)

~ ~

132 kV Latur 1105 MW 40 MVAR

(90 MW 75 MVAR)

132 kV Latur 270 MW 30 MVAR

(60 MW 45 MVAR)

132 kVGirwaliBus

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MONTH KWH 1998 KWH 1999 KWH 2000 KWH 2001

January 791500 1101100 1014800 401700

February 545000 938100 699100 239400March 667900 819800 663300* 262200

April 539400 790900 87400* 183400

May 512000 473200 -* 275400

June 164400* 459800 167700* 43800**

July 313900 1170300 442100

August 310400 948000 490900

September 330600 630400 342700October 500300 706100 350100

November 530400 854700 626000

December 307300* 1104100 542000

---Load shifted to another feeder --- Load of other feeder taken on this feeder

** --- kWh meter stopped due to leading PF

Note:

0.6 MVAR capacitor bank recommissioned at village Pandharee on Dt.28.11.2000

0.6 MVAR capacitor bank added at same location on Dt.4.12.2000

New 0.6 MVAR capacitor bank commissioned at Pokharni Phata on Dt.8.12.2000

KWH recorded on 11kV Matkuli feeder from 132 / 11 kV T/F at 132 kV Ashti substation

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0

200000

400000

600000

800000

1000000

1200000

Janu

ary

Feb

ruary

March

April

May

June Ju

ly

Aug

ust

Septembe

r

Octob

er

Novembe

r

Decembe

r

1998

1999

2000

2001

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Month Forecasted Energy sentout (kWH)

Actual Energy sent out(kWH)

Savings(kWH)

Remark

Dec 2000 689997 542000 147997 21.45

Jan 2001 624172 401700 222472 35.60

Feb 2001 520905 239400 281505 54.00

Mar 2001 562029 265200 296829 52.00

Apr 2001 511766 183400 328366 64.10

May 2001 451451 275400 176051 39.00

Total 3360320 1907100 1453220 43.24

Energy savings on 11 kV Matkuli feeder

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1.System requires high order reactive compensation.

2.Use of fixed value non switched/seasonal manual switchedcapacitors is economical.

3. Complementary switching for optimum compensation.

4. Dedicated setup for overall line loss reduction.