05 - Unbalanced Load Flow
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Transcript of 05 - Unbalanced Load Flow
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8/17/2019 05 - Unbalanced Load Flow
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ETAP Workshop Notes © 1996-2009 Operation Technology, Inc.
Unbalanced Load Flow
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8/17/2019 05 - Unbalanced Load Flow
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Slide 2© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Real Unbalanced Power
Systems• Distribution System
– 3-phase, 2-phase, and single-phase network
components
– Unbalanced loads
• Transmission System
– Untransposed long transmission line
– Abnormal operation with one phase out of service
– Unbalanced loads (e.g., electrical railway traction
motors)
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Slide 3© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Harmful Effects of System
Unbalance• Overheating of generators
• Nuisance tripping of protective relays
• Increased real power losses
• Transformer failure
• Radio communication interference
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Slide 4© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Unbalance Factors/Indexes
• System unbalance is considered by power
quality standards as a disturbance
• Voltage/Current unbalance factors
• Ratio of zero/negative sequence to positivesequence
• Voltage/Current unbalance indexes
• Ratio of average values to maximum
deviation of average values
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Slide 5© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Unbalanced Load Flow
Analysis
• Current Injection (CI) method
• The most robust algorithm ever developed
• Converge in less iterations than othermethods, especially for heavily loaded
systems
• Sparse matrix technique
• Unique modeling concepts
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Slide 6© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Sequence Models of
3-Phase Machines
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8/17/2019 05 - Unbalanced Load Flow
7/18Slide 7© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Unique Concepts of
3-Phase Machines
• Swing Machine
– The specified magnitude and the phase angle of the
positive sequence voltage only at the swing machine
terminal
• PV Machine
– The specified total output of 3-phase real powers and
the magnitude of the positive sequence voltage
• PQ Machine
– The specified total outputs of 3-phase real and reactive
powers
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8/17/2019 05 - Unbalanced Load Flow
8/18Slide 8© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Concepts of Load
Connections
• Single-Phase Loads
• Connected in the phase connection types of
AB, BC, CA, AN, BN or CN• Three-Phase Loads
• Connected in Delta, Wye or Wye-G
• The constant individual powers in Wye are
not allowed due to multiple solutions
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8/17/2019 05 - Unbalanced Load Flow
9/18Slide 9© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Modeling Capabilities
• A mixture of 3-phase, 2-phase and single-phase network components
• 3-phase machines with internal impedance
being considered
• Built-in calculator for overhead line
impedances
• Mutual coupling among overhead lines
• Transformers combined with load tap
changers (LTC) and phase shifters
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8/17/2019 05 - Unbalanced Load Flow
10/18Slide 10© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Modeling Capabilities
• 2-winding and 3-winding transformers ofvarious winding connections
• Lumped loads consisting of constant power,
constant impedance and constant currentcomponents
• Generator exciters with AVR or Mvar / PF
controllers
• Robust library of of commonly used
overhead transmission lines and cables
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8/17/2019 05 - Unbalanced Load Flow
11/18Slide 11© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Study Case
• Same pretense as Balanced Load Flow withmore detailed modeling, calculations, and
results
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8/17/2019 05 - Unbalanced Load Flow
12/18Slide 12© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Output Results
• State-of-the-art graphic display ofresults
• Graphical display of marginal andcritical under/over voltages
• Alert View displays
limit violations
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8/17/2019 05 - Unbalanced Load Flow
13/18Slide 13© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Reporting
• Customized output reports using Crystal Reports
®
• Individual phase and sequence voltage, current,
and power
• Voltage drops, losses,
power flows, power
factor, voltage/currentunbalance factors, etc.
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Example 1
© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
j l . 5
- j0 . 3
j0 04
T2
10 MVA
Gen1
? 5 MlJ
2 .1 - j0 . 1
2
1 .6
1 .5
~ : : : : I : S u b 2 ~ B ~ ~ - - ~ _ ,
Sub2A . s - j0 . 5 z j l . 4
l
Z j l Z
0 .9 - j0 . 2
1 .2
- j0 . 5
- j0 . 1
Z . 1 - j0 . 1 t
l
6
. 2 . 30.1
0 .2 j0 .1 0 .3
0 .2 j0 .1 0 .3
~ \ 1 taP)
~ \ 1
t Pc)
~ \ I t &
Syn1
-0 .9 j0 .2
-0.8
j0 .2
-0.9 j0 .3
T
1 5 / 1 0 / 5 MVA
jO .
SW)
3
jO
- j0 .08
- j Lb . .
- j0 . 2 0 .5
- j0 . 2 0 .5
Sub3 H e t
0.
1
0 j0 .1
0 j0 .1
j0 . 2
j0 .1
j0 .2
:r
CAP1
450
kva r
Syn3
3500
HP
1250 HP
0 .2 j0 .1
I..A.IVOU. 2
j
0 . 1
T
1 5
MVA
T4
)
CB22 ~ \ 1 taP)
Bus
0
.469 ~ \ 1 t Pc)
jo .1
o
.4
1
; .
~ t e a )
CB2;1 : .2 j0 .1 o.41
0 .2 j0 .1
Ill
DC Sys t e m
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8/17/2019 05 - Unbalanced Load Flow
15/18Slide 15© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Example 2
IEEE Four Node Test Feeder
• Characteristics of the Feeder
1. Two line segments with a 3-phase
transformer bank connected between the twosegments
2. Data is specified for balanced and
unbalanced loading at the most remote node
3. Transformer is specified for different
connection testing
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8/17/2019 05 - Unbalanced Load Flow
16/18Slide 16© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
U1
U7
us
99999992
MVAsc:
99999992
MVAsc:
99999992 MVAsc:
1853
j516
\(\1 ~ ' * ' )
15 4
2
j1361
\(\1
' * ' )
19 6
3
j1699
2164 j1644
4 7
2316
j9 90
'\z.4.7 17 4
j l l 2 2
\(\1
Bus1
\_1.. \(\1
Bu s
31
+2
97
j2 46
4 7
Bus27
+2
2
5
j1846
'\z.4.7
+2
368 j l l 9 6
'\z.4.7
' I ( ' J
\1.. \(\1
h 853
j516
\_1.. 4.
h 54 2
j1361
\_1..
4
+19 6 3
j1699
\_1.
_4 7 \(\1 ~
2164 j1644
2316
j99
17 4 j l l 2 2
\_1..
4.
2 97
j2 46
225 j1846
2368 j l l 9 6
Line1
Line1
2
Line14
44
'- \]
~ - ' )
\(\1 ~ ' * ' )
'$1 '- \] ~ - ' )
Bus3
\_1. (' .:)
r:>? '- \]
\_1.. (' .:)
Bu s 32
\_1.. (' .:)
\1.
~ . : ; : . )
Bus28
1. \
'- \]
e;,
'- \]
h 849
j499
~ ' - \ ]
h
528
\_1..
~ . : ; : . )
h
943
j1667
\_1..
~ . : ; : . )
' \ _ 1 . - ~
j1341 ¢ '---r
\ 6 '- \]
214 j1622
23 3
j9 62 \_1. ·
1696 j l l
4
\z.Z
2 75
j1993
22 3
1
j18 5
j l l 6 1
T1
T8
6
MVA
\(\1 ~ ' * ' )
T7
6 MVA
Bus4
< ; ~ 7 ' \
6 MVA
\(\1 ~ ' * ' )
' J O J ' ~ ~ )
'- \] ~ - p . : ) Bus3
< ; 1 7 ~ ' 1 ( \ J ~ ~ )
Bu s
3 4
~ - < ; 1 ' 1 ( \ J ~ ~ )
+
1325
~ . i i o ' i l
B
-
8/17/2019 05 - Unbalanced Load Flow
17/18Slide 17© 1996-2009 Operation Technology, Inc. – Workshop Notes: Unbalanced Load Flow Analysis
Example 3
IEEE 13 Node Test Feeder
• Characteristics of the Feeder
1. Short and relatively highly loaded for a 4.16
kV feeder
2. Overhead lines with variety of phasing
3. Shunt capacitor banks
4. In-line transformer
5. Unbalanced loading
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8/17/2019 05 - Unbalanced Load Flow
18/18Slide 18© 1996-2009 Operation Technology Inc – Workshop Notes: Unbalanced Load Flow Analysis
Line603 BC300
Line605 CN300
LUI lp6
188 kVA
CAP1
100 kvar
U1
Bus650
T1
1000000 00 liVAs c
T
500 kVA
Line60
3
BC500 Line60
2
l t r 31
170 kUJ
Line604 ACN300
Load2
154 kVA
Bus632
16 3
121
t 1 22
+
1059
j479
504 j98
1026 j3 32
Line
01 22
LUI lp9
116 kVA
Li ne6 0 1 33
Bus680
LUI lp7
116
kVA
-0
- j O
0 - j O
+-
o j o
- - r l - ' ~
_1. 3 < \( I ltl
~ 1 9 1
o > - ~
- 1 ) 1 . 1
Bus633
162
121
t122
115
9 2
9 3
LUI lp1
494
kVA
j
11
0
j90
j90
1 .
8 l VAb
Cab1e6
06 500
488
j1
68
- j1 8 1
t2
91 j 3 7
+
44 j121
0
jO
120
j 2
5
- ' ~
LUI lp 5
3
\(\( I t l ' ~
227
kVA
.1-9
1
\ ( I d > - ~
Bu s675
+485 j 190 t j 1 91
68
j60 0
j2 42
290
j 2
1 2 0 j 1 75
LUI lp4
971
kVA
r
CAP2
6 00 k
var