Impact of Voltage Reduction on Load, Line Loss and Generation

7/24/2019 Impact of Voltage Reduction on Load, Line Loss and Generation

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Impact of Voltage Reduction on

Load, Line Loss and generation

Sushanta Paul

Prof. Ward Jewell


2/13

2

Introduction

Numerous voltage reduction program for

conservation or peak-load reduction are in use

in the USA and around the world

Design of this program has been based on

experimental evidence

This work presents technical analysis on the

impact of voltage reduction on load, line loss

and generation


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Impact of load type on line loss and load

demand

Constant Power Load: , current

will Increase, as a result line loss will increase

Constant Current load: , since current

remains constant, no change in line loss

Constant Impedance Load: , again

, finally current will decrease, as a result line loss

will decrease

*)tan( IVtconsjQP

*

)tan(

VjQPtconsI

jQP

VtconsZ

2

)tan(

V

jQPI

*


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Impact of Voltage Reduction on Line

Loss for Composite Load ModelConst. PQ load dominant:

Increasing effect of line loss for const. PQ loadswill dominate the decreasing effect of line loss forconst. Z loads resulting in the increase in line loss

Const. Z load dominant: Decreasing effect of lineloss for const. z loads will dominate the increasingeffect of line loss for const. PQ loads resulting inthe decrease in line loss

Const. I load dominant: Line loss will increase if% const. PQ load > % const. Z load or loss willdecrease if % const. Z load > % const. PQ load


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Impact of Load Model on Load, Line LossLoad Model Power Consumption Line Loss

Constant Power Constant Increase

Constant Current Decrease Constant

Constant Impedance Decrease Decrease

Composite Load

(i) Constant Power load

dominant

(ii) Constant Current

load dominant

(iii) Constant impedance

load dominant

Decrease

Decrease

Decrease

Increase

Increase if % of const.

power load > % of const.

impedance load

or

Decrease if % of const.

impedance load > % ofconst. power load

Decrease

PLoad

P

ZP ILoad

I

Load PP ,

ZP ILoad

I

Load

P

Load PPP

ZLoad

P

ZLoad

I

Load

I

Load

P

Load PPPP ZP


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Variation in Active power Generation: Pgen = PLoad + PLoss

Impact of Reduced Voltage on Active Power Generation

Decrement positive, Increment negative

Therefore, PLoad + PLoss > 0

PGen > 0 i.e. active power generation will decrease

Again,

By (1) and (2),

(2)

(3)

(1)


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Variation in reactive power generation:

Due to voltage reduction, reactive power will decrease if,

(4)

Or increase if,(5)

Now at reduced voltage,

System with dominant constant P,Q load:and

Equ. (5), i.e. reactive power generation will increase

System with dominant constant Z load:

Equ. (4), i.e. reactive power generation will decrease

Since;



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System with dominant constant I load:

Equ. (4), i.e. reactive power generation will decrease


Impact of Voltage Reduction on Power Consumption

Composite Load ModelActive Power

Generation

Reactive Power

Generation

Const. PQ Load

Dominant Decrease IncreaseConst. Z Load

DominantDecrease

Decrease, if

Increase, if

Const. I Load

DominantDecrease

Decrease, if

Increase, if


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800

806 808 812 814

810

802 850

818

824 826

816

820

822

828 830 854 856

852

832

888 890

838

862

840

836860834

842

844

846

848

864

858

Const. PQ load

dominant

Const. Z load

dominant

IEEE 34-bus System

Load under regulator 814:

Const. PQ: 195 kW, 97 kVAr

Const. Z: 34 kW, 17 kVArConst. I: 45 kW, 22 kVAr

Capacitors under regulator 852: 750 kVAr

Sub-

station

Voltage

(V)

Total LoadTotal Line

Loss

Power

Supplied

from

Substation

(kW)( kVAr) (kW) (kVAr)(kW) (kVAr)

122 1772 1053 278 197 2050 451

121 1772 1053 278 197 2050 451

120 1770 1052 279 198 2048 452

119 1767 1050 280 199 2047 452

118 1764 1049 282 199 2046 453


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Load under regulator 852: Const. Z Load Dominant

Const. Z: 566 kW, 395 kVAr, Const. I: 517 kW, 266 kVAr Const. PQ: 341 kW, 210 kVAr

Sub-

station

Voltage

(V)

Total Load Total Line Loss Power Generation

(kW) ( kVAr) (kW) ( kVAr)(kW) (kVAr) (kW) (kVAr) (kW) (kVAr) (kW) (kVAr)

124 1772 1053 1771 1052 278 197 310 219 2050 452 2081 873

123 1772 1053 1771 1052 278 197 310 219 2050 452 2081 873

122 1762 1046 1761 1046 275 196 307 217 2037 453 2068 869

121 1745 1036 1748 1038 270 193 303 214 2016 455 2051 864

120 1732 1027 1733 1028 266 190 297 211 1999 456 2030 858

Load under regulator 852: Const. I Load Dominant

Const. I: 566 kW, 395 kVAr, Const. Z: 517 kW, 266 kVAr, Const. PQ: 341 kW, 210 kVAr

Sub-

station

Voltage(V)

Total Load Total Line Loss Power Generation

(kW) ( kVAr) (kW) ( kVAr) (kW) (kVAr) (kW) (kVAr) (kW) (kVAr)(kW) (kVAr)

124 1730 1028 1728 1027 256 181 287 201 1986 412 2014 831

123 1730 1028 1728 1027 256 181 287 201 1986 412 2014 831

122 1721 1023 1719 1022 253 179 283 199 1974 414 2002 828

121 1709 1016 1708 1015 249 176 279 196 1958 417 1987 825

120 1695 1008 1694 1007 245 173 274 192 1936 421 1968 820

Increase inreactive power

Decrease inreactive power


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11Impact of Voltage Reduction on IEEE 13-Bus System

0.920.940.96

0.981

1.021.04

0.965 0.9736 0.9822 0.9908 0.9994 1.008 1.0166

Gen. (Const. PQ load dominant) Gen. (Const. Z load dominant

Gen. (Const. I load dominant) Load (Const. PQ load dominant)

Load (Const. Z load dominant) Load (Const. I load dominant)

Voltage (V)

Gener

ation

(pu)

Load

(pu)

Active Load and Generation vs. Voltage

Const. PQ load

Const. Z load

Reactive Load and Generation vs. Voltage

Const. PQ load

0.750.785

0.820.855

0.890.925

0.960.995

0.965 0.9735 0.982 0.9905 0.999 1.0075 1.016

Gen.(Const. PQ load dominant) Gen. (Const. Z load dominant)

Gen. (Const.I load dominant) Load (Const.PQ dominant)

Load (Const.Z load dominant) Load (Const. I load dominant)

Ge

neration

(pu)

Load

(pu)

Voltage

Const. Z loadConst. PQ load


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0.0298

0.0313

0.0328

0.0343

0.965 0.9736 0.9822 0.9908 0.9994 1.008 1.0166Loss (Const. PQ load dominant) Loss (Const.Z load dominant)

Loss (Const. I load dominant)

Voltage(V)

Line

Loss(pu) Const. PQ load

Const. I load

Const. Z load

-0.00028

0.00772

0.01572

0.02372

0.03172

0.03972

0.04772

0.055720.06372

0.07172

0.07972

0.965 0.9736 0.9822 0.9908 0.9994 1.008 1.0166

Gen. decr. (Const.PQ load dominant) Gen. decr. (Const. Z load dominant)

Gen. decr. (Const. I load dominant) Load decr. (Const. PQ load dominant)

Load decr. (Const.Z load dominant) Load decr. (Const. I load dominant)

Loss incr. (Const. PQ load dominant) Loss decr. (Const.Z load dominant)

Loss incre. (Const. I load dominant)

Generation

decrease

(pu)

Load

decrease

(pu)

Lossdecrease/increa

se(pu)

Voltage

Line Loss vs. Voltage

Decrease/Increase in Load, Line Loss and Generation vs. Voltage

Const. Z load

Const. I load

Const. PQ load


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ConclusionDue to voltage Reduction:

A decrease in both active and reactive load for all composite

load model

Line Loss increases for dominant const. PQ load, decreases for

dominant const. Z load and for dominant const. I load line loss

will increase if % const. PQ load > % const. Z load or decrease

if % const. PQ load < % const. Z load

Active power generation decreases for all composite load

model

Reactive power generation increases for const. PQ load. For

const. Z and I load, reactive power generation decreases if

or increases if

Documents

Impact of Voltage Reduction on Load, Line Loss and Generation