Understanding Power Factor Correction
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Transcript of Understanding Power Factor Correction
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UNDERSTANDING
POWER FACTOR
CORRECTION
Dr. Ir. Mohamed Fuad Faisal
Asset Management Department,
Distribution Division, TNB
Presentation contents
Understanding Electrical Power
Understanding Electrical Energy & Energy Bills
Managing Low Power Factor
Impact of Low Power Factor
Benefits of High Power Factor
Methods to Improve Low Power Factor
Locations to install capacitors Types of Power Factor Capacitors
Sizing of Capacitor
Energy Saving Devices
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Understanding
Electrical Powers
P= kW
Q=kVAr
S= kVA
S=(P2+Q2)
Relationships kW, kVAr, kVA & PF
Power Factor (PF) =kW
kVA
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Types of Loads (Equipment)
Resistive Inductive CapacitiveIncandescent lighting Motors Capacitor
Heating element Transformers
ETC Chokes, ETC
Watt, Kilowatt VAr, KiloVAr VAr, KiloVAr
Equipment Label: kW & Power Factor
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Equipment Label: HP (Horsepower) &
Power Factor (PF)
No label for kW & kVAr
1 hp = 0.746 kW
7.5 hp = 5.5 kW
PF = 0.81 = kW
kVA
kVAr = (kVA2-kW2)
Electrical Energy
& Electricity Bills
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Energy Meter
kiloWatt
kiloVAr
Air conditioner
Energy Meter
kiloWatt
kiloVAr
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Definition of Power & Energy
Energy Meter
kiloWatt
kiloVAr
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P= kW or kWh
Q=kVAr or kVArh
S= kVA or kVAh
S=(P2+Q2)
Average Power Factor (PF) = kWh
kVAh
Relationships kWh, kVArh, kVAh & PF
Power Factor (PF) =kW
kVA
Energy Meter
kiloWatt
kiloVAr
Example for Domestic Customers
Energy cost= RM 0.28/kWh
Cost = RM 0.28/kWh x 330 kWh
= RM 92.40
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Kilang ABC
Energy cost (kWh)Energy cost = kWh (1month) x h
Maximum Demand (kW)Maximum Demand = Highest kW(1month) x Tariff
kVArh
Power FactorPower factor penalty for power factor < 0.85 (0.9)
Charges for Non
Domestic Customers
Managing
Low Power Factors
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Kilang ABC
Energy cost (kWh)Energy cost = kWh (1month) x h
Maximum Demand (kW)Maximum Demand = Highest kW(1month) x Tariff
kVArh
Power FactorPower factor penalty for power factor < 0.85 (0.9)
Charges for Non
Domestic Customers
P= kW or kWh
Q=kVAr or kVArh
S= kVA or kVAh
S=(P2+Q2)
Average Power Factor = kWh
kVAh
DEFINITION OF POWER FACTOR
Power Factor =kW
kVA
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Equipment Causing Low Power Factor
Lightly loaded induction motor. Examples of this type of
equipment and their approximate power factors are:
80% power factor or better: Air conditioners, pumps, center less
grinders, cold headers, up setters, fans or blowers.
60% to 80% power factor: Induction furnaces, standard stamping
machines and weaving machines.
60% power factor and below: Single stroke presses, automated
machine tools, finish grinders, welders.
Example 1Energy recorded by TNB energy meter
kWh = 123,345.24
kVarh=87,453.23
What is the value of average power factor ?
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kWh = 123,345.24
kVarh = 87,453.23
kVAh = (123,345.242 + 87,453.232)
= 151,202
Average PF = kWh / kVAh
= 123,345.24 / 151,202
= 0.815
LIMTS FOR AVERAGE POWER FACTOR
Non Domestic Customers are advise to maintain
power factor at minimum of 0.85 (0.90)
PF = 1.0
PF=0.85 (0.9)Power
Factor
PF=0.75 (0.75)
No Surcharge
Surcharge
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All Tariffs imposed Power Factorlimits except Tariffs A & G
Tarif A Domestic
Tarif B LV Commercial
Tarif C1 MV Commercial
Tarif C2 MV Peak/Off-Peak
Tarif D LV Industry
Tarif E1 MV Industry
Tarif E2 MV Industry Peak/Off
Tarif E3 HV Industry
Tarif F LV Mining
Tarif F1 MV Mining
Tarif F2 MV Mining Peak/OffTarif G Street Lighting
CALCULATION OF AVERAGE
POWER FACTOR PENALTY
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Average Power Factor Charges
Power Factor Description
PF > 0.85 No charge
PF = 0.85 No charge
0.75 < PF < 0.85 For every different of 0.01,
additional charge of 1.5 %
from monthly bill
PF < 0.75
For every different of 0.01,
additional charge of 3.0%from monthly bill
(0.75 < PF < 0.90)
(0.90)
(0.90)
EXAMPLE 2One 11 kV LPC has monthly power factor of 0.60 & the monthlyelectricity bill is
RM 4,800.
What is the actual monthly electricity bill?
Charge1 = (0.85 - 0.75)/0.01 x1.5 % = 15 %
Charge 2 = (0.75 - 0.60)/0.01 x 3.0 % = 45 %
Overall charge = (15 % + 45 %) = 60 %
Power factor penalty = 60% x RM 4,800.00 = RM 2,880.00.
Monthly ElectricBill = Energy Bil (kWh) + power factor penalty
Actual electricity bill = RM 4,800 + RM 2,880 = RM 7,680.00
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Impact of Low
Power Factors
Reactive Power Problem (1)
Condition 1
Power Factor = 1.0, Load = 50 kW,
Load kVA = kW / PF = 50 kVA
Load Current = kVA / (3 x 480 Volt) = 60 Amp
Condition 2
Power Factor = 0.7, Load kW = 50 kW,
Load kVA = kW / PF = 50 kW / 0.7 = 72 kVA
Load Current = kVA / (3 x 480 Volt) = 86 Amp
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Reactive Power Problem (1)
60 Amp
86 Amp
Load = 50 kW
PF =1.0
Load = 50 kW
PF =0.7
100kW
100kW
100kW
100kW
100kW
48.43kVar
75kVar
102kVar
133.33kVar
100 kVApf=1.00
111.11 kVApf=0.90
125 kVApf=0.80
142.8 kVApf=0.70
166.7 kVApf=0.60
Reactive Power Problem (2)
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100kW
90kW
80kW 60
kW
70kW
43.59kVar
60kVar 71.41
kVar80kVar
100 kVApf=1.00
100 kVApf=0.90
100 kVApf=0.80
100 kVApf=0.70
100 kVApf=0.60
Reactive Power Problem (3)
Transformer size
100 kVA
Reactive Power Problem (4)
Condition 1
Power Factor = 0.45
Tx Size = 1000 kVA
Load kVA = 1,777 kVA
% TX Load = 177 %
Condition 2 Power Factor = 0.9
Tx Size = 1000 kVA
Load kVA = 888 kVA
% TX Load = 88 %
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Reactive Power Problem (5)
Condition 1
Power Factor = 1.0
Load kVA = 50 kVA
Current = 50 kVA/ (3x480) =60 Amp
Cable resistance = 5 ohm
Losses = I2 x R = 602 x 5 = 18,000 Watt
Condition 2
Power Factor = 0.7
Load kVA = 72 kVA
Current = 72 kVA/ (3x480) =86 Amp
Cable resistance = 5 ohm
Losses = I2 x R = 862 x 5 = 36,980 Watt
Losses = Watt
In 1 hour (h), the losses
value will be kW x h
Summary of Impacts of Low Power Factors
a low power factor will inflict power factorpenalty to customers
a lower power factor can cause increase inline current and cause technical losses (I2R)for both customers and TNB.
a low power factor can increase the kVA loadfor TNB transmission/distribution systems(use more of system capacity kVA).
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Benefits of High
Power Factors
Benefits of High Power Factor Correction
No power factor penalty to customers
Reduce line current and minimize technicallosses (I2R) for both customers and TNB.
Reduce use of system capacity kVA for bothcustomers and TNB.
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Methods to Improve
Low Power Factors
Methods to Improve Low PF
Install power factor correction capacitorsFixed or Switch Capacitors
Synchronous Condenser When a Synchronous motor operates at No-Load and
over-exited then its called a synchronous Condenser.
Whenever a Synchronous motor is over-exited then it
provides leading current and works like a capacitor
Adjust power factor settings (COGEN)
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Locations to
Install Capacitors
Locations to Install Capacitors
Capacitors connected at a distribution board and
controlled independently from the individual
starters is known as Capacitor Bulk Correction".
Capacitors connected at each load is known as
Capacitor Load Correction".
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Capacitor Bulk Correction
Capacitor bulk correction will minimize
average power factor penalties
If the customers want to minimize the average power factor
penalty, they must install suitably sized capacitor banks exactly
after the energy meter.
Energy Meter Capacitor
Load
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Locations to install capacitor for
minimizing power factor penalties
OPEN
INCOMER
1.5MVA
DY11
X
X 11 kV
X
1.5 MVADY1
X415 Volt
1MVADY11
M
M
ProductionEquipment
Compressors
Chillers
208 Volt
UTILITY
M
Servo Drives
M
Cooling Tower
M
ASD
Locations to install capacitor for
minimizing power factor penalties
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Capacitor load correction will minimize
line current, losses and improve average
power factor.
Capacitor load correction will minimize
line current, losses and improve averagepower factor.
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Capacitor load correction will minimize
line current, losses and improve average
power factor.
Types of Power Factor
Correction Capacitors
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Delta 415 Volt Capacitor for
Schools & Shops
Delta 415 Volt Capacitor
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11 kV Pole Mounted Capacitor
Y-Y Ungrounded 11 kV
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Y-Y Ungrounded 33 kV
Y-Y Ungrounded 132 kV
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Sizing of Power
Correction Capacitors
Methods to Size Capacitors
Use the power factor correction reference
(PFCR) table
Perform load profiling at selected sites.
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57
Power Factor Correction Reference Table80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100
50 0.982 1.008 1.034 1.06 1.086 1.112 1.139 1.165 1.192 1.22 1.248 1.276 1.306 1.337 1.369 1.403 1.442 1.481 1.529 1.59 1.732
51 0.937 0.962 0.989 1.015 1.041 1.067 1.094 1.12 1.147 1.175 1.23 1.231 1.261 1.292 1.324 1.358 1.395 1.436 1.484 1.544 1.687
52 0.893 0.919 0.945 0.971 0.997 1.023 1.05 1.076 1.103 1.131 1.159 1.187 1.217 1.248 1.28 1.314 1.351 1.392 1.44 1.5 1.643
53 0.85 0.876 0.902 0.928 0.954 0.98 1.007 1.033 1.06 1.088 1.116 1.144 1.174 1.295 1.237 1.271 1.308 1.349 1.397 1.457 1.654 0.809 0.835 0.861 0.887 0.913 0.939 0.966 0.992 1.019 1.047 1.075 1.103 1.133 1.164 1.196 1.23 1.267 1.308 1.356 1.416 1.559
55 0.769 0.795 0.821 0.847 0.873 0.899 0.926 0.952 0.979 1.007 1.033 1.063 1.09 1.124 1.156 1.19 1.228 1.268 1.316 1.377 1.519
56 0.73 0.756 0.782 0.808 0.834 0.86 0.887 0.913 0.94 0.968 0.996 1.024 1.051 1.085 1.117 1.151 1.189 1.229 1.277 1.338 1.4857 0.692 0.718 0.744 0.77 0.796 0.822 0.849 0.875 0.902 0.93 0.958 0.986 1.013 1.047 1.079 1.113 1.151 1.191 1.239 1.3 1.442
58 0.655 0.681 0.707 0.733 0.759 0.785 0.812 0.838 0.865 0.893 0.921 0.949 0.976 1.01 1.042 1.076 1.114 1.154 1.202 1.263 1.405
59 0.618 0.644 0.67 0.696 0.722 0.748 0.775 0.801 0.828 0.856 0.884 0.912 0.939 0.973 1.005 1.039 1.077 1.117 1.165 1.226 1.368
60 0.584 0.61 0.636 0.662 0.688 0.714 0.741 0.767 0.794 0.822 0.85 0.878 0.905 0.939 0.971 1.005 1.043 1.083 1.131 1.192 1.334
61 0.549 0.575 0.601 0.627 0.653 0.679 0.706 0.732 0.759 0.787 0.815 0.843 0.87 0.904 0.936 0.97 1.008 1.014 1.096 1.157 1.299
62 0.515 0.541 0.567 0.593 0.619 0.645 0.672 0.698 0.725 0.753 0.781 0.809 0.836 0.87 0.902 0.936 0.974 0.982 1.062 1.123 1.265
63 0.483 0.509 0.535 0.561 0.587 0.613 0.66 0.666 0.693 0.721 0.749 0.777 0.804 0.838 0.87 0.904 0.942 0.949 1.03 1.091 1.233
64 0.45 0.476 0.502 0.528 0.554 0.58 0.607 0.633 0.66 0.688 0.716 0.744 0.771 0.805 0.837 0.871 0.909 0.918 0.997 1.058 1.2
65 0.419 0.445 0.471 0.497 0.523 0.549 0.576 0.602 0.629 0.657 0.685 0.713 0.74 0.774 0.806 0.84 0.878 0.887 0.966 1.027 1.169
66 0.388 0.414 0.44 0.466 0.492 0.518 0.545 0.571 0.598 0.626 0.554 0.682 0.709 0.743 0.775 0.809 0.847 0.857 0.935 0.996 1.138
67 0.358 0.384 0.41 0.436 0.462 0.488 0.515 0.541 0.568 0.596 0.624 0.652 0.679 0.713 0.746 0.779 0.817 0.828 0.905 0.966 1.108
68 0.329 0.355 0.381 0.407 0.433 0.459 0.486 0.512 0.539 0.567 0.595 0.623 0.65 0.684 0.716 0.75 0.788 0.798 0.876 0.937 1.079
69 0.299 0.325 0.351 0.377 0.403 0.429 0.456 0.482 0.509 0.537 0.565 0.593 0.62 0.654 0.686 0.72 0.758 0.769 0.84 0.907 1.049
70 0.27 0.296 0.322 0.348 0.374 0.4 0.427 0.453 0.48 0.508 0.536 0.564 0.591 0.625 0.657 0.691 0.729 0.741 0.811 0.878 1.02
71 0.242 0.268 0.294 0.32 0.346 0.372 0.399 0.425 0.452 0.48 0.508 0.536 0.563 0.597 0.629 0.663 0.701 0.712 0.783 0.85 0.992
72 0.213 0.239 0.265 0.291 0.317 0.343 0.37 0.396 0.423 0.451 0.479 0.507 0.534 0.568 0.6 0.634 0.672 0.685 0.754 0.821 0.963
73 0.186 0.212 0.238 0.264 0.29 0.316 0.343 0.369 0.396 0.424 0.452 0.48 0.507 0.541 0.573 0.607 0.645 0.658 0.727 0.794 0.936
74 0.159 0.185 0.211 0.237 0.263 0.289 0.316 0.342 0.369 0.397 0.425 0.453 0.48 0.514 0.546 0.58 0.618 0.631 0.7 0.767 0.909
75 0.132 0.158 0.184 0.21 0.236 0.262 0.289 0.315 0.342 0.37 0.398 0.426 0.453 0.487 0.519 0.553 0.591 0.604 0.673 0.74 0.882
76 0.105 0.131 0.157 0.183 0.209 0.235 0.262 0.288 0.315 0.343 0.371 0.399 0.426 0.46 0.492 0.526 0.564 0.578 0.652 0.713 0.855
77 0.079 0.105 0.131 0.157 0.183 0.209 0.236 0.262 0.289 0.317 0.345 0.373 0.4 0.434 0.466 0.5 0.538 0.552 0.62 0.687 0.829
78 0.053 0.079 0.105 0.131 0.157 0.183 0.21 0.236 0.263 0.291 0.319 0.347 0.374 0.408 0.44 0.474 0.512 0.525 0.594 0.661 0.803
79 0.026 0.052 0.078 0.104 0.13 0.156 0.183 0.209 0.236 0.264 0.292 0.32 0.347 0.381 0.413 0.447 0.485 0.499 0.567 0.634 0.776
8 0 0 0 .0 26 0 .0 52 0 .0 78 0 .1 04 0 .1 3 0 .1 57 0 .1 83 0 .2 1 0 .2 38 0 .2 66 0 .2 94 0 .3 21 0 .3 55 0 .3 87 0 .4 21 0 .4 59 0 .4 73 0 .5 41 0 .6 08 0 .7 5
8 1 0 0 .02 6 0 .0 52 0 .0 78 0 .10 4 0 .1 3 0 .1 57 0 .1 84 0 .2 12 0 .2 4 0 .2 68 0 .29 5 0 .3 29 0 .36 1 0 .3 95 0 .43 3 0 .4 47 0 .51 5 0 .5 82 0 .72 4
8 2 0 0 .0 26 0 .0 52 0 .0 78 0 .1 05 0 .1 31 0 .1 58 0 .1 86 0 .2 14 0 .2 42 0 .2 69 0 .3 03 0 .3 35 0 .3 69 0 .4 07 0 .4 21 0 .4 89 0 .5 56 0 .69 8
83 0 0. 026 0. 05 2 0. 07 9 0 .105 0. 132 0 .1 6 0. 18 8 0 .21 6 0. 243 0. 277 0. 30 9 0 .34 3 0 .38 1 0. 395 0. 463 0.5 3 0 .67 2
84 0 0 .02 6 0. 05 3 0 .079 0. 106 0. 13 4 0. 16 2 0 .1 9 0. 217 0. 251 0. 28 3 0 .31 7 0 .35 5 0. 369 0. 437 0 .50 4 0 .64 5
85 0 0.027 0.053 0 .08 0.108 0.136 0.164 0.191 0.225 0.257 0.291 0.329 0.343 0.417 0.478 0.62
86 0 0.026 0.053 0.081 0.109 0.137 0.167 0.198 0.23 0.265 0.301 0.317 0.39 0.451 0.593
87 0.027 0.055 0.082 0.111 0.141 0.172 0.204 0.238 0.275 0.29 0.364 0.425 0.56788 0 0.028 0.056 0.084 0.114 0.145 0.177 0.211 0.248 0.262 0.237 0.398 0.54
89 0.028 0.056 0.086 0.117 0.149 0.183 0.22 0.234 0.309 0.37 0.512
90 0.028 0.058 0.089 0.121 0.155 0.192 0.206 0.281 0.342 0.484
91 0.03 0.061 0.093 0.127 0.164 0.176 0.253 0.314 0.456
92 0.031 0.063 0.097 0.134 0.143 0.223 0.284 0.426
93 0 0.032 0.066 0.103 0.113 0.192 0.253 0.395
94 0.034 0.071 0.079 0.16 0.221 0.363
95 0.037 0.042 0.126 0.187 0.328
96 0 0.089 0.15 0.292
97 0 0.047 0.108 0.251
98 0 0.061 0.203
99 0 0.142
O
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in
a
l
P
ow
e
r
F
a
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t
o
r
i
n
%
Desired Power Factor in %
58
Performing a Load Profiling
OPEN
INCOMER
X 11 kV
X
1.5 MVA
DY1
X415 Volt
1MVA
DY11
M
M
Production
Equipment
Compressors
Chillers
208 Volt
UTILITY
M
Servo Drives
M
Cooling Tower
M
ASD
PQ recorder
No.1
PQ recorder
No.2
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59
Event #1 at 11/09/2006 12:08:58.000
BVrms, CVrms, BVrms, CV rms Voltage Journal Trigger Normal To Low
Timeplot
Max At Min At
AQFnd(kVAR) AVG 1764 11/13/2006 21:10 917.6 11/13/2006 21:10
BQFnd(kVAR) AVG 1916 11/09/2006 19:30 1041 11/09/2006 19:30
CQFnd(kVAR) AVG 1775 11/09/2006 19:50 935.4 11/09/2006 19:50
TOTQFnd(kVAR) AVG 5442 11/09/2006 19:30 2894 11/09/2006 19:30
11/10/2006
Friday
11/11/2006
Saturday
11/12/2006
Sunday
11/13/2006
Monday
11/14/2006
Tuesday
11/15/2006
Wednesday
1000
2000
3000
4000
5000
kVAR
A Q Fn d( kVA R) (a vg ) B Q Fn d( kV AR ) ( av g) C Q Fn d( kV AR ) ( av g) T OT QF nd (k VA R) (a vg )
Created with DranView 6.0.23
Base kVAR
Maximum kVAr
Summary of Capacitor
Sizing & Placement
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Overall Procedures for Capacitor Sizing
& Placement
Start
Capacitor sizing
Identify location
Technical
assessment
Design &
specificationsInstallation Asset Mgmt
Objectives
Energy Saving Devices
(ESD)
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Energy Saving
Device (ESD) ?
Brand XXXSmartKit
?
Does A Energy Saving Card (ESC)Exist to achieve Energy Efficiency ?
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Energy Saving Card (ESC) ?
ABC
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Thank You