Download Load_Benchmarking_update_EPRI

Benchmarking WECC
Composite load model
Parag Mitra
Sr. Engineer
Anish Gaikwad
Sr. Project Manager
© 2016 Electric Power Research Institute, Inc. All rights reserved.
Load Model Benchmarking
 Versions of software used
 PSLF 19.02
 PSS/E 33.9
 PowerWorld 19
 DSATools (TSAT) V16.1.27 (Release date Dec 14, 2016)
Uniform implementation
across all platforms
 Composite load model
channels are now available in
DSATools
 Channel names straightforward
in Powerworld
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Test system
3 bus test system
proposed by Siemens
PTI
Generator and
exciter use standard
parameters
GENROU
IEEET1
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Initialization of composite load model
Motor A
Motor B
Motor C
Slip
P
Q
Slip
P
Q
Slip
P
Q
PSSE
0.035
3.924
3.055
0.0195
3.924
3.347
0.0195
1.962
1.673
PSLF
0.041
3.925
3.095
0.021
3.924
3.389
0.021
1.962
1.694
Powerworld
0.041
3.925
3.095
0.021
3.926
3.389
0.021
1.962
1.66
DSATools
0.041
3.925
3.045
0.02
3.925
3.246
0.02
1.962
1.623
Motor D
Electronic
ZIP
P
Q
P
Q
P
Q
PSSE
4.906
2.37
1.96
0.95
2.94
1.43
PSLF
4.91
2.37
1.96
0.95
2.94
1.43
Powerworld
4.906
2.37
1.96
0.95
2.94
1.43
DSATools
4.91
2.37
1.96
0.95
2.94
1.43
Swing Bus
Mid Bus
HV Bus/Substation
bus
Internal Load Bus
V
θ
V
θ
V
θ
V
θ
PSSE
1.01
0
1.00
-0.28
1.000
-0.84
0.999
-
PSLF
1.01
0
1.007
-0.28
1.000
-0.84
0.999
-
Powerworld
1.01
0
1.007
-0.28
1.000
-0.84
0.999
-
DSATools
1.01
0
1.007
-0.28
1.000
-0.84
0.9986
-
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Possibly due
to leakage
reactance Xa
Performance of Motor A (Load torque=constant)
Responses are almost identical across
the 4 platforms
Although similar in magnitude some fast
oscillations can be seen in the TSAT output
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Stalling of Motor A (WECC Recmd. Tripping/Reconnection)
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Stalling of Motor A (No tripping)
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Without trip and reconn.
With trip and reconn.
Stalling of Motor A
1. Had a discussion with Siemens. The
difference is because the motor in PSSE
starts up a little bit later.
2. This is possibly due to difference in the value
of Xa between the different vendors. PSS/E
assumes a different value than PSLF and
others
3. TSAT recommends using a time step of 0.25
cycles or less for double cage IMs. Default
time step is 0.5 cycles (This was causing
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TSAT to have numerical issues in our previous
simulations)
© 2016 Electric Power Research Institute, Inc. All rights reserved.
Stalling/Restart of Motor A (Plots by Gary Thomann PTI)
Xa= 0.8 times sub-transient reactance
Xa= 0.6 times sub-transient reactance,
Results match PSLF closely
There is no standard documentation
for this parameter
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Reconnection of Motor B (Load torque α Speed2)
Active power at load bus
Reactive power at load bus
100% motor tripping
Voltage at load bus
Speed
• PSLF does not reconnect.
• TSAT does not let the motor to slow
down as it did previously.
• TSAT suggested using trapezoidal
integration for this simulation
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Performance of Electronic Load
The model response is identical across
all the platforms in the current versions
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Performance of ZIP Load
The model response is identical across
all the platforms in the current versions
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Low voltage performance of ZIP Load
b. Active power at load bus
a. Voltage at load bus
b. Reactive power at load bus
40% constant Z, 40% Constant I, 20% Constant P
The differences need to be sorted out
1. How is the low voltage behavior of the
ZIP component modeled?
2. Is this implementation uniform across all
the software platforms?
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Performance of Motor D
Active power at load bus
Reactive power at load bus
PSLF output is different than the other
tools. The hump is missing.
Latest correspondence with Bill Price
from PSLF indicates that this issue has
been resolved and the updated model
now matches with the other software
tools
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Motor D: Vstall and Vstallbrk
•
PSS/E and Powerworld both handles a Vstall
= 0, replaces it with Vstllbrk
•
PSLF 19.0_02 has numerical issues if Vstall
is small. However, if Vstall is set to 0, PSLF
changes it to 0.6
•
TSAT generates the following message
Source: Powerworld Documentation
Problem is with Vstall and
Tstall. Rstall and Xstall are ok
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
EPRI suggestion
Some vendors may be doing this already (above figures from Powerworld)
Proposed change
Instructions:
If (Vstall<Vstallbrk)
•
LMTF to supply recommended value of Vstall
•
To prevent stalling set Vstall as recommended
value and set Tstall as 9999
Vstall=Vstallbrk
end
Motor D does not stall
Motor D stalls
•
Motor moves on yellow marked path
when voltage decreases
•
Motor moves on yellow marked path when
voltage decreases
•
Motor moves on yellow marked path
back when voltage recovers
•
Restartable part –yellow
•
Non restartable part – green (till they trip)
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Current status
PSS®E
PSLF™
Powerworld
TSAT
Initialization




Motor A, B, and C for a voltage
dip




Motor A, B, and C during stalled
condition




Tripping and reconnection
capabilities of Motor A, B and C




Electronic load








Motor D (performance with
voltage dip)




Motor D (Vstall and Vstllbrk)




Static load
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© 2016 Electric Power Research Institute, Inc. All rights reserved.
Together…Shaping the Future of Electricity
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© 2016 Electric Power Research Institute, Inc. All rights reserved.