14 - parameter tuning
TRANSCRIPT
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section will investigate the relationship between a parameter of a mode and the model
response process for some typical transfer function models.
3. Tuning of Power System Dynamical Model Parameters
A power system dynamical device usually consists of different types of elements. These
elements can be mathematically presented by some typical dynamical components or
transfer functions. The following describes a number of typical dynamical components inpower system dynamical models, and illustrates how the responses of these components
are affected by varying their parameters. Also, a simplified model of a single generator
power system is investigated in this section.
Inertial Components: Its transfer function is shown as Figure 3.1. The inertial
component is usually used to model the regulator amplifier, governor relay, or
electric/hydraulic converter. Figure 3.1 and 3.2 display the responses of this component
when applying a step input with different time constant and gain values. As can be seenfrom Figure 3.1, the raising rate of response will increase with reducing time constant
value. But the settle down value of response would not be affected by varying timeconstant value. When increasing gain value, as shown in Figure 3.2, both the raising rate
and settle down value of response will be increased.
Figure 3.1 Inertial Component Responses for Changing
Time Constant
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Figure 3.4, when increasing time constant value, the raising rate and overshooting
magnitude of response will increase, but the falling rate during the decay segment will bedecreased, thus, the settle down time of response would last longer. When increasing gain
value, as shown in Figure 3.5, the raising rate and overshooting magnitude of response
also will increase, but the falling rate would not be changed.
Figure 3.4 Inertial-Differential Component Responses for
Changing Time Constant
Figure 3.5 Inertial-Differential Component Responses for
Changing Gain
Single Generator Power System Model: Figure 3.6 shows a simplified model of a
single generator power system. The block Ks and Kd are defined as system synchronizing
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coefficient and system damping coefficient, respectively. These two coefficients
represent the equivalent effects of generator, AVR, governor, loads and other systemcomponents. Figures from 3.7 to 3.12 display the power angle and speed responses of the
power system model when a load shed is applied with different model parameters. As can
be seen from Figure 3.7 and 3.8, when increasing damping coefficient Kd, the oscillation
magnitudes of power angle and speed responses will be reduced, but the oscillationfrequency of them is not changed. When increasing synchronizing coefficient Ks, as
shown in Figure 3.9 and 3.10, the oscillation magnitudes of power angle and speed
responses will be reduced and the oscillation frequency of them will be increased. Also, itis found that the initial power angle becomes smaller with increasing Ks. When reducing
generator inertial coefficient H, as shown in Figure 3.11 and 3.12, the raising rate,
overshooting magnitude and oscillation frequency of speed response will be increased,but settle down time becomes shorter. For the power angle response, its falling rate, and
oscillation frequency will be increased, but its undershooting magnitude will be
decreased and settle down time also becomes shorter.
Figure 3.6 Simplified Single Generator Power System Model
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Figure 3.7 Generator Speed Responses for Changing
Damping Coefficient
Figure 3.8 Generator Power Angle Responses for Changing
Damping Coefficient
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Figure 3.9 Generator Speed Responses for Changing
Synchronizing Coefficient
Figure 3.10 Generator Power Angle Responses for Changing
Synchronizing Coefficient
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Figure 3.11 Generator Speed Responses for Changing
Inertial Coefficient
Figure 3.12 Generator Power Angle Responses for Changing
Inertial Coefficient
4. Examples of Tuning Power System Dynamical Model Parameters
In this section, some examples are presented to illustrate how to tune the parameters of
power system dynamical models utilizing the site test or system incidence recording data,so as to make the responses of dynamical model match the real recording data.
4.1Generator Start-up Case
This is a real test case. The test system, as shown in Figure 4.1, is a Hydro GenerationStation as the backup power system of a Nuclear Power Plant. The test process includes:
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first start a generator unit, at the same time flash the generator field winding, when
generator terminal voltage reaches approximately 70% to 90% of rated output voltage,then a voltage relay trips the appropriate circuit breakers and connect the emergency load
from the nuclear generation plant to the generator. The generator AVR and governor
models are shown as Figure 4.2 and 4.3. The typical parameters of the models are listed
in Table 4.1 and 4.2. When using the typical parameters in simulation study, as can beseen from Figures 4.4, 4.6, 4.8 and 4.10, the responses of generator speed, voltage, power
and field voltage do not match the site test results. By investigating the response curves,
obviously, some transfer function time constants and gains of both AVR and governormodels and the generator damping and inertial coefficients need to be tuned up properly.
A set of modified model parameters are listed in Table 4.1 and 4.2. The responses of the
system corresponding to the parameter modifications show a very good match to the sitetest results as displayed in Figures 4.5, 4.7, 4.9 and 4.11. In this project study, it is
discovered that the response of the motor start simulation will not correctly express the
real situation if the formula coefficients of motor load model are not presented properly.
The formula coefficients of motor load model usually can be obtained by using curve
fitting technology based on the load torque curve. In most cases, the manufacturers onlyprovide the load torque curves under the speed range from 0 to 100%. It is no problem to
simulate the motor start if the system frequency within this speed range. Otherwise, thesimulation results will not truly reflect the actual situations. In this test case, the generator
speed ever overshoots to 120% of rated speed at a period of time. Figure 4.13 shows the
response of a motor electrical power during start up have big discrepancy against the sitetest result when using the load model with the speed range from 0 to 100%. When
remodeling the load torque curve covered the speed range to 120% as given in Figure
4.12, the response of the motor electrical power corresponding to the modified loadmodel shows a very good match to site test results as shown in Figure 4.14.
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KGEN 2 KGEN 1
W/OMod#2
4kV B1TS
600V LC 3X4 600V LC 3X8
4kV 3TC
TX-3X5
HP IP -3A600 HP
LP IP -3A400 HP
RBSP-3 A250 HP
LPSWP- 3A600 HP
TX-3X8
MCC 3XS1
3EPTC13
3PTC3
3TC/D/E-3B1T
3TC-3B1T
3TD/E-3B1T
3TC-3B2T
NO
B1TS-3B1T
3X5 Test 13X8 Test 1 3X8 Test 23X4 Test 23X4 Test 1
TX-3X4
13. 2kV Keo#113. 2kV Keo#2
U3 4kV bus13
CT4
Underground
NO
4kV B2TS
4kV 3TE4kV 3TD
600V LC 3X10600V LC 3X6600V LC 3X5 600V LC 3X9
TX-3X9 TX-3X6 TX- 3X10
MCC 3XS2
LP IP -3B400 HP
RBSP-3 B250 HP
LPSWP-3B600 HP
HPIP-3B600 HP
3EPTE123PTE3
MCC 3XS3
3PTD3 3EPTD13
3TD-3B1T
3TE-3 B1T3TC/D/E-3B2T
3TD-3B2T
3TE-3B2T
3TD/E-3B2T
NO
B2TS-3B2T
3X5 Test 23X6 Test 1 3X6 Test 23X9 Test 1 3X9 Test 2
EFDWP- 3A600 HP
EFDWP- 3B600 HP
HP IP -3C600 HP
Figure 4.1 Test System for Generator Start-up
Figure 4.2 Exciter/AVR Model Diagram of Hydraulic Generator
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Parameter Typical Tuned
RC 0.0 0.0
XC 0.03 0.03
TR 0.0 0.0
TC 0.0 0.0
TBB 0.0 0.0
KA 100 70
TA 0.02 0.02KF 0.5 0.12
TF 0.5 0.8
KC 0.1 0.1
VVLR 1.07 1.07
KVL 120.0 120.0
TVL 0.05 0.05
KVF 1.0 1.0
TH 0.05 0.05
VImax 0.17 0.17
VImin -0.17 -0.17
VRmax 3.66 3.66
VRmin 0.0 0.0
Vdc 125 125
Rf 0.15 0.06VHZ 0.74 0.74
TD 2.5 2.5
Vfb 87.5 87.5
Ifb 585 585
Vref 1.025 1.025
Table 4.1 Typical and Tuned Parameters of Exciter Model
Figure 4.3 Governor Model Diagram of Hydraulic Generator
Parameter TP Q GC TG RP RT TR H D
Typical 0.04 1 2.5 1 0.02 0.4 5.5 7 2
Tuned 0.04 1 2.5 1.41 0.02 0.4 7.5 4.94 1.1
Table 4.2 Typical and Tuned Parameters of Governor Model
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Figure 4.4 Comparison between Simulated Generator Speed Response(Using Typical Parameters) and Site Measured Speed
Figure 4.5 Comparison between Simulated Generator Speed Response
(Using Tuned Parameters) and Site Measured Speed
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Figure 4.6 Comparison between Simulated Generator Voltage Response
(Using Typical Parameters) and Site Measured Voltage
Figure 4.7 Comparison between Simulated Generator Voltage Response
(Using Tuned Parameters) and Site Measured Voltage
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Figure 4.8 Comparison between Simulated Generator Electrical Power Response
(Using Typical Parameters) and Site Measured Electrical Power
Figure 4.9 Comparison between Simulated Generator Electrical Power Response
(Using Tuned Parameters) and Site Measured Electrical Power
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Figure 4.10 Comparison between Simulated Generator Field Voltage Response
(Using Typical Parameters) and Site Measured Field Voltage
Figure 4.11 Comparison between Simulated Generator Field Voltage Response
(Using Tuned Parameters) and Site Measured Field Voltage
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Figure 4.12 Induction Motor Load Torque Curve Fitting
Figure 4.13 Comparison between Simulated Induction Motor Electrical Power
Response (Using Typical Parameters) and Site Measured Electrical Power
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Figure 4.15 Test System for Diesel Generator Load Shed
Figure 4.16 Exciter Model Diagram of Diesel Generator
Parameter Typical Tuned
KA 156 240
KC 0.001 0.001
KE 0.08 0.08KF 0.1 0.27
KI 9 9
KP 0.08 0.08
TA 0.05 0.05
TE 1.0 4
TF 3.0 3.0
TR 0.005 0.005
Vrmax 17.5 17.5
Vrmin -15.5 -15.5
Table 4.3 Typical and Tuned Parameters of Exciter Model
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Figure 4.17 Governor Model Diagram of Diesel Generator
Parameter Typical Tuned
Droop 5.0 5.0
ThetaMax 60.0 60.0
ThetaMin 4.0 4.0Alpha 0.04 0.027
Beta 0.02 0.0192
Rho 0.1 0.3
K1 128 119
Tau 0.1 0.09
T1 0.15 0.151
T2 0.12 0.12
H 1.9 1.69
D 4.0 7.0
Table 4.4 Typical and Tuned Parameters of Governor Model
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Figure 4.18 Comparison between Simulated Generator Frequency Response
(Using Typical Parameters) and Site Measured Frequency
Figure 4.19 Comparison between Simulated Generator Frequency Response
(Using Tuned Parameters) and Site Measured Frequency
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Figure 4.20 Comparison between Simulated Generator Voltage Response
(Using Typical Parameters) and Site Measured Voltage
Figure 4.21 Comparison between Simulated Generator Voltage Response
(Using Tuned Parameters) and Site Measured Voltage
4.3Network Short-Circuit Fault Test Case
This test case is to simulate a system response when a short-circuit fault occurred on a
bus. The test system is shown in Figure 4.22. The simulation events include: short-circuitfault occurs at MCC feeder Bus3, voltage relay trips some load at Bus-A and Bus-B when
voltage drops to 50% during the fault, in 0.38 seconds the circuit breaker 52GH is tripped
to disconnect fault point, in 0.8 seconds the circuit breaker 52B4 is tripped to disconnectthe tie link to utility. The actual measured current and voltage of generator G4 and
current at branch 52B4 are displayed in Figure 4.23. The simulation responses of the
system current and voltage for using typical generator parameters listed in Table 4.5 andusing tuned parameters listed in Table 4.5 are shown as Figure 4.24 and 4.25,
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respectively. As can be seen from Figure 4.25, the response of the system current and
voltage using tuned parameters are very close to the actual measured data.
Bus4
Bus- BBus2
Bus1
T3
12. 5 MVA
pump273. 936 kW
pump3937 kW
pump483. 175 kW
CB4
52B4
52GH
LUMP15. 848 MVA
LUMP210. 75 MVA
pump5
345 kW
LUMP34. 458 MVA
CB5
CB6
LUMP410. 75 MVA
3.3 k
3.3 k3.3 kV
65 kV
3.3 kV
Bus-A
Bus3
3.3 kV
Power Gr i d
pump173. 936 kW
G415. 111 MW
Figure 4.22 Test System for Short-Circuit Fault
Parameter Typical Tuned
Xd 1.48 0.75
Xq 1.48 0.74
Xd 0.215 0.15
Xq 0.45 0.16
Xd 0.136 0.12
Xq 0.136 0.13
Td0 7.05 7.05
Tq0 1.0 1.0
Td0 0.042 0.042
Tq0 0.18 0.18
H 5.4 8
D 5 1
Table 4.5 Typical and Tuned Parameters of Generator
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Figure 4.23 Site Voltage and Current Recordings DuringShort-Circuit Fault
Figure 4.24 Simulated Generator Voltage and Current Responses
(Using Typical Parameters)
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Figure 4.25 Simulated Generator Voltage and Current Responses
(Using Tuned Parameters)