Improvements to D-axis Test - WECC - Improvements to D-axi… · Typical modeled saturation...
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April 8, 2021 Improvements to D-axis Test WECC MVS Meeting Quincy Wang Song Wang
Transcript of Improvements to D-axis Test - WECC - Improvements to D-axi… · Typical modeled saturation...
April 8, 2021
Improvements to D-axis Test
WECC MVS Meeting
Quincy Wang Song Wang
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o Determine Xd from test –IEEE 115, D-axis test
o Influence of magnetic saturation in D-axis test
o Relation between rotor field current and Xd
o Xd and Kw from online measurement results
o Simulation with known Xd & offsets in D-axis test
o Summary and future work
Outline
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Unsaturated Xd from Test
o Calculated from OCC and SCC (IEEE Std-115)
o D-axis load rejection (IEEE Std-115)
(𝐸𝐸𝑓𝑓𝑓𝑓 = 𝑉𝑉𝑞𝑞 + 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓)
o Can include properly-considered saturation effect
o Simulation of D-axis test for Xd , X’d , X”d , T’do , T”do
A low terminal voltage magnitude is required prior to the load rejection test to avoid the impact of saturation phenomenon on obtained parameters.
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Influence of Magnetic Saturation
H
B
Locus of tip of B-H loops
Typical modeled saturation function
Source: IEEE Std 115-2019
• After D-axis load rejection, the flux level is highly possible not on the modeled saturation function line
• Using measured field voltage/current in d-axis simulation to determine Xd may inherently have some error from the measurement
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Relation Between Ifd and Xd
𝐼𝐼𝑓𝑓𝑓𝑓 = 𝑓𝑓(𝐼𝐼𝑓𝑓 ,𝑋𝑋𝑓𝑓𝑑𝑑,𝑉𝑉𝑞𝑞 ,𝑅𝑅𝑎𝑎𝐼𝐼𝑞𝑞 , 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑖𝑖𝑠𝑠𝑠𝑠 𝑓𝑓𝑠𝑠𝑓𝑓𝑠𝑠𝑠𝑠𝑠𝑠… )Neglecting (𝑅𝑅𝑎𝑎𝐼𝐼𝑞𝑞):GENROU : 𝐼𝐼𝑓𝑓𝑓𝑓 = 1 + 𝑆𝑆𝑓𝑓 𝑉𝑉𝑞𝑞 + 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 +𝑆𝑆𝑓𝑓 𝑋𝑋𝑓𝑓" 𝑖𝑖𝑓𝑓GENSAL : 𝐼𝐼𝑓𝑓𝑓𝑓 = 1 + 𝑆𝑆𝑓𝑓 𝑉𝑉𝑞𝑞 + 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 +𝑆𝑆𝑓𝑓 𝑋𝑋𝑓𝑓′ 𝑖𝑖𝑓𝑓GENQEC : 𝐼𝐼𝑓𝑓𝑓𝑓 = ⁄1 + 𝑆𝑆𝑎𝑎 𝑉𝑉𝑞𝑞 + 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 +𝑆𝑆𝑎𝑎 𝑋𝑋𝑙𝑙𝑖𝑖𝑓𝑓 1 − 𝐾𝐾𝑤𝑤𝑖𝑖𝑓𝑓
Does the constant Xd fit
well in field measured results?
Source: IEEE Std 115-2019
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Relation Between Ifd and XdZero Power-Factor Saturation line before saturationGENROU : 𝐼𝐼𝑓𝑓𝑓𝑓 = 𝑉𝑉𝑞𝑞 + 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓GENSAL : 𝐼𝐼𝑓𝑓𝑓𝑓 = 𝑉𝑉𝑞𝑞 + 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓GENQEC : 𝐼𝐼𝑓𝑓𝑓𝑓 = ⁄𝑉𝑉𝑞𝑞 + 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 1 − 𝐾𝐾𝑤𝑤𝑖𝑖𝑓𝑓
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0 1000 2000 3000 4000 5000Gen
erat
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tato
r Vol
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and
Cur
rent
(p
.u.)
Generator Field Current (A)
OCC
SCC
0 P.F.
Air-gap // to Air-gapGENQEC:
0-P.F. line
∆𝑉𝑉𝑡𝑡∆𝐼𝐼𝑓𝑓𝑓𝑓
= 1 − 𝐾𝐾𝑤𝑤
(in per unit)
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Relation Between Ifd and Xd
• Calculate Xd based on measured Ifd
• Xd calculated from online measurement results
• Using multiple points to minimize error
• 𝑋𝑋𝑓𝑓𝑑𝑑 = 𝑓𝑓(𝐼𝐼𝑓𝑓 , 𝐼𝐼𝑓𝑓𝑓𝑓 ,𝑉𝑉𝑞𝑞 ,𝑅𝑅𝑎𝑎𝐼𝐼𝑞𝑞 , 𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑖𝑖𝑠𝑠𝑠𝑠 𝑓𝑓𝑠𝑠𝑓𝑓𝑠𝑠𝑠𝑠𝑠𝑠… )
GENQEC :
𝑦𝑦 = 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 = 1 − 𝐾𝐾𝑤𝑤𝑖𝑖𝑓𝑓 𝐼𝐼𝑓𝑓𝑓𝑓 − 1 + 𝑆𝑆𝑎𝑎 𝑉𝑉𝑞𝑞 + 𝑅𝑅𝑎𝑎𝑖𝑖𝑞𝑞 − 𝑆𝑆𝑎𝑎𝑋𝑋𝑙𝑙𝑖𝑖𝑓𝑓
Use a sizable number of measurement points to examine 𝑦𝑦 = 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓
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Xd and Kw from online measurements
𝑦𝑦 = 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 for measured online operating points with 𝐾𝐾𝑤𝑤 = 0
𝑖𝑖𝑓𝑓
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Xd and Kw from online measurements
𝑦𝑦 = 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 for measured online operating points with 𝐾𝐾𝑤𝑤 = 0.4
𝑖𝑖𝑓𝑓
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Xd and Kw from online measurements
𝑦𝑦 = 𝑋𝑋𝑓𝑓𝑖𝑖𝑓𝑓 for measured online operating points with 𝐾𝐾𝑤𝑤 = 0.2235
𝑖𝑖𝑓𝑓
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Xd and Kw from online measurements
𝑋𝑋𝑓𝑓 = 0.982 and 𝐾𝐾𝑤𝑤 = 0.2235
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Xd and Kw from online measurements
𝑋𝑋𝑓𝑓 = 0.982 and 𝐾𝐾𝑤𝑤 = 0.2235
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D-axis test Simulation with known Xd
• Terminal voltage change always fits the given Xd
• Can focus on validating X’d X”d T’do T”do
• Consistent parameter validation results independent of the operating point for d-axis load rejection
• Misalignments between modeled and measured field voltage/current do not affect validated parameters
𝐴𝐴𝑑𝑑𝑑𝑑𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑑𝑑𝑑𝑑𝑠𝑠 ∶
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D-axis test Simulation with known Xd
0.00.10.20.30.40.50.60.70.80.91.01.1
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Gen
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r Cur
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(PU
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Generator Field Current (PU)
Measured
GENQEC
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Fiel
d Cu
rren
t (A)
Fiel
d Vo
ltage
(V)
Time (s)
Field Voltage
Field Current
1. Note the difference between the modeled and the measured/calculated field current
2. Include these offsets in the simulation by adding these offset to measured field voltage that was fed to the generator model for simulation
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D-axis test Simulation with known Xd
Guaranteed match with the known Xd , and offsets considered
Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
0.72
0.75
0.78
0.81
0.84
0.87
0.90
0.93
0.96
0.99Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
0.72
0.75
0.78
0.81
0.84
0.87
0.90
0.93
0.96
0.99Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
0.72
0.75
0.78
0.81
0.84
0.87
0.90
0.93
0.96
0.99Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00
0.72
0.75
0.78
0.81
0.84
0.87
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0.96
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MeasurementSimulation
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D-axis test Simulation with known Xd
Guaranteed match with the known Xd , and offsets considered
Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00
0.75
0.78
0.81
0.84
0.87
0.90
0.93
0.96
0.99Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00
0.75
0.78
0.81
0.84
0.87
0.90
0.93
0.96
0.99Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00
0.75
0.78
0.81
0.84
0.87
0.90
0.93
0.96
0.99Generator terminal voltage (pu)
Time (sec)0.00 5.00 10.00 15.00 20.00 25.00 30.00 35.00 40.00 45.00 50.00 55.00 60.00
0.75
0.78
0.81
0.84
0.87
0.90
0.93
0.96
0.99
MeasurementSimulation
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Summary
Xd fitted from online measurements is suitable to represent the generator in a wide range of operating conditions
Kw obtained together with Xd from online measurement makes perfect sense, inherently with VEE curve accuracy considered
D-axis parameter validation simplified with more consistent results expected
Simple method and easy application leading to better way for generator model parameter validation
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Next Steps
𝑋𝑋𝑙𝑙 ?
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Next Steps
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