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Introduction to PSCAD and Applications
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Training Course Presented by the Manitoba HVDC Research Centre
Course Date: Location: Lead Instructor:
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PSCAD GETTING-STARTED TUTORIALS
Getting Started and Basic Features
Prepared by: Date: Revision: Date:
Dharshana Muthumuni August 2005 3 March12, 2007
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Getting Started - Tutorial 1 Objective(s): Getting familiar with PSCAD. Getting familiar with different sections of the Master Library. Different ways to access the master library. Creating a simple case. Data entry. Plotting and control. Interactive controls.
T1.1 Create a new case by using either the Menu or Toolbar. A new case should appear in the Workspace settings entitled noname [psc]. Right-click on this Workspace settings entry and select Save As… and give the case a name. NOTE: Do not use any spaces in the name! Create a folder called c:……/PscadTraining/Tutorial_01. Save the case as case01.psc T1.2 Open the main page of your new case. Build a case to study the inrush phenomena when energizing a transformer. The component data is as shown. The transformer is rated 66/12.47 kV. RL RRL
Ia
66 kV BUS
66 kV,60 Hz Source Z+ = 3.9Ohms / 75.58 deg Z0 = 14.95 Ohms / 80.46 deg
BRK
E_66
BRK
#2
#1
Y-Y Transformer 7.5 MVA Z = 6.14 % Full load loss = 0.3% No load loss = 0.5% No load current 1 %
Timed Breaker Logic Open@t0
1e6
Fig.1 Transformer energizing circuit. T1.3 Plot the currents (Ia) and voltages (E_66) on the HV side of the transformer. Note: Ia and Ea contains the three waveforms of the three phases. 3 / 72
Fig.2 Basic steps to create a graph with a selected signal. T1.4 The LV side of the transformer is not connected to a load or any other system equipment. The breaker is closed at 0.5 s to energize the transformer 66 kV side. Inrush is related to core saturation. Verify that saturation is included in the model used for this simulation. Ask your instructor to explain the large resistance connected to the HV side. Inrush current magnitude depends on the ‘point on wave’ switching conditions. Use a manual switch to operate the breaker. Note the point on wave dependency of the inrush peak. Main ... BRK_Control C
O
BRK
1
Fig.3 Two state switch attached to a control panel.
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T1.5 Modify the case to include a 12.47 kV/0.5 MVA (Wound rotor type) induction machine. This case will be used to study the process of starting an Induction motor. The component data is as shown. 12.47 kV BUS
81m U/G 54m OH
Main ...
Capacitor
R_C1
800 KVars per phase C
R_C1
42.5 [uH]
40.94 [uF]
O
R_C1
Ib
Feeder
1
EN484
COUPLED
PI SECTION
Short line of 7.4 km Z+ = 0.2 E-4 + j0.3 E-3 Ohms/m Z0 = 0.3 E-3 + j0.1 E-2 Ohms/m Use default values for the capacitances
B_mot
Etrv
Emot
N
B_mot
Timed Breaker Logic Open@t0
0.001 IM
This block models the mechanical characteristics of a typical load.
W
TL
* 0.8
S
2 X
W
Mechanical Torque TIN 0.0
0.0
TIN
500 kVA Induction machine. Squerriel Cage Type. 13.8 kV(L-L) 7.697 kV (Phase) Irated = 0.02804 [kA] Inertia = 0.7267 [s] Stator resistance = 0.005 PU Rotor Resistance = 0.008 PU
You may use the wire mode to connect different components. T1.6 Enter the component data. Note: Use ‘typical’ data for the machine. T1.7 Plot the currents on either side of the transformer (ia and ib). T1.8 The input torque to the machine is equal to 80% of the square of the speed. Derive this signal using control blocks. i.e
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Tm 0.8 w2 Use control blocks to implement the above equation.
Your instructor will explain the calculation program structure of EMTDC and the definition of ‘electric’ and ‘control’ type models. T1.9 The breaker (initially open) should be closed at 0.2s to start the motor. T1.10 Plot the machine speed, the mechanical torque and the developed electric torque. Note: Some variables can be measured from within the component. These are normally listed under the parameter section ‘Internal output variables’
If time permits…
T1.11 Add a load of 1 MVA at 0.8-power factor at 12.47 kV. The same transformer supplies this load. Does the load see an unacceptable voltage sag during motor start?
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Data: Motor 500 kVA Induction machine. Wound rotor Type. 13.8 kV(L-L) 7.697 kV (Phase) Irated = 0.02804 [kA] Inertia = 0.7267 [s] Stator resistance = 0.005 PU Rotor Resistance = 0.008 PU
Short Line Short line of 7.4 km Z+ = 0.2 E-4 + j0.3 E-3 Ohms/m Z0 = 0.3 E-3 + j0.1 E-2 Ohms/m Use default values for the capacitances
Mechanical Load model This block models the mechanical characteristics of a typical load. Mechanical Torque * 0.8
X2
W
TIN
Capacitor leg Capacitor 800 KVars per phase R_C1
42.5 [uH]
40.94 [uF]
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PSCAD ESSENTIAL TRAINING Tutorials 1 – 6 1. 2. 3. 4. 5. 6. 7. 8.
Initializing a simulation Switching study Transformers and inrush Transmission lines Power electronic switching Induction machine dynamics Synchronous Machines and controls Wind farms and doubly fed machines
Prepared by: Dharshana Muthumuni Date: August 2005 Revision: 2 Date: Feb 16, 2007
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Tutorial 1 – Two Area Power System – Initializing the simulation to a specific load flow. T1.1 Create a new case by using either the Menu or Toolbar. A new case should appear in the Workspace settings entitled noname [psc]. Right-click on this Workspace settings entry and select Save As… and give the case a name. NOTE: Do not use any spaces in the name! Create a folder called c:……/PscadTraining/T_01. Save the case as T_01_a.psc T1.2 Open the main page of your new case. Build a case representing a simplified two area power system as shown in the figure below. A 55 km transmission line connects Station A to a 100 MW wind farm. All other connections to Station A are represented by an equivalent 230 kV source. The equivalent source impedance is derived from a steady state fault study at 60 Hz. The line is represented by its series reactance. The transformer is represented by its impedance, referred to the 230 kV side.
Station A 55 km line
33/230 kV, Z = 0.1 pu
230 kV
0.14
0.074
RRL
100 MVA Transformer
230 kV Eq. source
RRL
Wind Farm
Z_positive = 10 Ohms at 88 deg. Z_zero = 7 Ohms at 82 deg.
Q1
RL
RL
P1
P2 Q2
Q2
Fig1. Two area system T1.3 The wind farm is also represented by a network equivalence. The positive sequence impedance of this source at 33 kV is 1 Ohm at 89 deg. NOTE: Referred to the 230 kV side the impedance value Ans:48.577 at 890
T1.4 The voltage behind the equivalent impedance at the wind farm is 35 kV. The phase angle is 7 degrees. Determine the power flow across the line. Note: Converted to the 230 kV side, the equivalent voltage is 243.939 kV at 7 deg Note: The simplified calculations are outlined in the accompanying MathCAD worksheet.
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T1.5 Plot the power and reactive power flow at both ends of the line. These signals can be obtained from the voltage source models as internal outputs. T1.6 Use proper scale factors inside the Output Channels’ to convert PU values to MW and MVar. Verify the results. T1.7 How do you change the time step, the simulation time and the plot time? How do you determine the simulation time step? T1.8 Can you save results to external output files for post processing? T1.9 If you specified to write data to output files, where are they located?
Save the case!
The case should be saved as T_01_b.psc before proceeding. Different parts of the simulation model can be arranged inside page modules. PSCAD allows ‘nested’ page modules. If you make a change to your existing case, PSCAD will identify the page modules where changes took place. Only these modules will be recompiled. (Time savings in large cases) T1.10 Create a page module and include the equivalent source for the wind farm inside this module as shown in the figures 2 and 3. What is the use of the ‘XNODE’ component? Note: Your instructor will briefly discuss the use of ‘signal transmitters’ which can also be used to transmit (control) signals from a page to another.
a 0.14
0.074
RRL
Farm
RL
Wind
P2 Q2
Q2
Fig.2 Main page
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RRL RL
a
P1 Q1
Fig.3. Subpage
Save the case! The case should be saved as T_01_c.psc before proceeding. T1.11 Modify the source at Station A to control its parameters externally. Add a control panel to specify these values. Can the values be changed during a simulation? Note: Make sure that the angle is specified in degrees (parameter setting inside the source model) Note: Observe the effect of varying the voltage angle/magnitude on P and Q flow
Ph
Main : Controls
F
RRL
V230 250
90
220
-90
230
0
60.0
V RL
FTYPE 10 9 8 7 6 5 4 3 2 1 1
Fig.4. External control of the source parameters.
T1.12 Modify the circuit to include breakers, breaker controls, meters and the PSCAD ‘fault component’. The case should look like as shown in figure 5. Plot, E1, I1 and the rms value of E1.
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Wind Farm
a
BRK2
BRK1
I1 E1
Timed Breaker Logic Closed@t0
V
Q2
60.0 BRK1
BRK3 BRK2
Timed Fault Logic
Timed Breaker Logic Closed@t0
RL
Q2
F
P2
A V
E1
RRL
Timed Breaker Logic Closed@t0
BRK3
I1 0.074 [H]
Ph
0.14 [H]
Fault inception - 0.4 s and at 0.404 s
E1 0 = No Fault 1 = Phase A to Ground 2 = Phase B to Ground 3 = Phase C to Ground 4 = Phase AB to Ground 5 = Phase AC to Ground 6 = Phase BC to Ground 7 = Phase ABC to Ground 8 = Phase AB 9 = Phase AC 10 = Phase BC 11 = Phase ABC
Main : Controls V230
Ph230
250
90
220
-90
230
0
FTYPE 10 9 8 7 6 5 4 3 2 1 1
Fig.5. Meters, breakers and faults. T1.13 Simulate an A-G fault. The fault inception time is 0.4s. The fault duration is 0.5 s. Note the dc offset of I1. (The dc offset can cause mal-operation of protection due to CT saturation. We will study this in later on as a separate example.)
T1.14 What factors influence the initial dc offset and its rate of decay? Change the fault inception time to 0.404 s and observe the results. T1.15 Breaker 3 is initially closed. Open and close this breaker at 0.5 s and 0.65 s respectively. Save the case! The case should be saved as T_01_d.psc before proceeding. T1.16 Include a FFT block in your simulation cases shown in figure 6. Convert I1 to its sequence components. Verify the results of the FFT for different fault types. Add a ‘poly-meter’ to observe the frequency spectrum. Note: The instructor will demonstrate the use of the ‘phasor meter’.
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1 2 I1 1
XA
2
XB
3
XC
I1 I1
1
1
Mag+ Mag- Mag0 (31) (31) (31) Ph+ (31) FFT Ph(31) F = 60.0 [Hz] dcA
dcB
Ph0 (31) dcC
Fig.6. FFT Block. T1.17 Load the case T_01_e.psc from the example cases given to you as course material. Study the ‘sequencer units’ available to define a series of timed events. Save the case!
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Tutorial 2 – Capacitor Switching Study: T2.1 Create a folder called c:……/PscadTraining/T_02. Save the case T_01_e.psc as T_02_a.psc. The utility plans to add 300 MVars of capacitive reactive power at station A to support the 230 kV bus voltage. A transient study is required to design equipment of this installation. Calculations and simulations are required to determine the values/ratings of the associated limiting reactors (inrush and outrush) Modify the simulation case to include a sub-page as shown in fig. 1. GT230
230 kV Voltage support Cap. Bank
Ph F
RRL
60.0 V RL
Fig.1 Capacitor banks at Station A. The circuit inside the sub page represents a 230 kV capacitor bank with 4 steps per phase (see attached diagrams). Each step is rated at 25 Mvar/phase. The capacitor banks are solidly grounded. The inrush and the outrush reactors sizes are to be determined so that the switching transients do not exceed the breaker capabilities and are within the IEEE standards. The values of the outrush/inrush reactors have been determined using IEEE C37.06.2000. T2.2 Use manual breaker controls to switch the breakers R1, R2 and R4. Also measure the currents in the breakers. T2.3 Add a timed breaker component to control breaker R3, measure the currents in R3. Note: Discuss with your instructor the purpose of making R3 operation controllable.
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T2.4 Add meters to measure the currents and voltages on the system side of the outrush reactor. T2.5 Run the case with R1 closed, R2 and R4 open, and R3 set to close at 0.2 s. T2.6 Observe the peak value and frequency of oscillation of the current in R3. T2.7 Observe the peak value and frequency of oscillation of the current at the outrush reactor. T2.8 Note the differences between (7) and (8). Discuss the results. Important: Ensure that you are using the proper time step and for visualization purposes, the proper plot step! T2.9 A Peak inrush current depends on POW switching. This should be studied to ensure that the breaker meets the TRV and di/dt capabilities. T2.10 Use the Multiple Run component to control the R3 closing time. Also record the currents in Breaker R3 and main feeder current. Set the multiple run to switch for 5 sequential points on the wave. Can we do random switching over a cycle? Can we optimize the run length using a snapshot? Take a snapshot at 0.199sec and the run multiple run for 20 sequential points on the wave. Compare your results with IEEE standard results. Can the simulation time step be changed when the case is run from a snapshot file? T2.11 What are some considerations for the selection of time-step for this type of simulation?
T2.12 EXTRA: Check the impedance spectrum using the ‘Harmonic Impedance’ component. This is an important step in the design of capacitor banks. The addition of the capacitors can give rise to system resonances that are not acceptable. Is this circuit appropriate to check for system resonances? Why? (not enough details of the system around the Station A bus is included to capture the frequency effects)
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1.00E-06 1.00E-06 1.00E-06 1.00E-06 1.00E-06
Series1
1.00E-06 1.00E-06 1.00E-06 1.00E-06 1
3
5
7
9
11 13
15
17 19
Save the case!
The case should be saved as T_02_b.psc before proceeding. T2.13 Modify the circuit as shown in figure 2 to include surge arrestors. The surge arrestors should protect the capacitors from switching over voltages. Restrike of capacitors breaker can cause large over-voltage transients and is usually the criteria for the selection of MOVs. Discuss the data entry for the MOV model.
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0.00317
0.05635 [MW] -3.988e-005 [MVAR]
0.09202 [MW] -79.7 [MVAR]
Closed@t0 Logic Breaker Timed
R3
R2 R2
MOV
0.05635 [MW] -3.988e-005 [MVAR]
R2
0.08013 [MW] -79.82 [MVAR]
R1 R1
kJoules
Imov
Closed@t0 Logic Breaker Timed
Outrush Reactors MOV
R3
R4 R4
Fig.2. Surge arresters. T2.13 Breaker R3 is initially closed. It is opened at 0.204 s but re-strikes at 0.2124 s. Observe the energy accumulation in the MOV of phase A. can the MOV handle this energy? Is a statistical study required to design the MOV ratings? Save the case!
The case should be saved as T_03_a.psc before proceeding.
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Tutorial 3 – Inrush current and line energizing. T3.1 Create a folder called c:……/PscadTraining/T_03. Save the case T_02_b.psc as T_03_a.psc. Open the capacitor main breaker R3. Keep all other breakers closed. Make the ‘fault’ component inactive. Most transient studies require the accurate modeling of transformers and transmission lines. Transformer inrush requires the accurate modeling of the non-linear iron core. Switching transient studies require the modeling of transmission lines to include the effects frequency dependent line parameters and traveling wave phenomena. T3.2 Use detailed models to represent the 33/230 kV transformer and the 55 km transmission line. The transformer has a Y-Y configuration and consists of three single phase units. The no load current is 1 %. The no load and copper losses are 0.003 pu and 0.002 pu respectively. The conductor arrangement of the line is as shown below. dependent phase model to represent the line.
G1 10 [m]
C2 5 [m]
C1
Use the frequency
G2 10 [m] C3 10 [m]
30 [m]
Tower: 3H5 Conductors: chukar Ground_Wires: 1/2"HighStrengthSteel 0 [m]
Fig.1. 230 kV Transmission tower.
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Timed Breaker Logic Open@t0 Timed Breaker Logic Open@t0 Wind Farm
a
I2 BRK1A
Three Phase RMS Voltage Meter BRK1B
3 Phase RMS BRK1C
GT230
BRK2 #1
Cap. Bank
Line_01
BRK3 I1
#2
E1
Ph
E2 Line_01 Line_01
RL
Timed Breaker Logic Open@t0 E1
60.0
V
Q2
I1 E1
Timed Breaker Logic Open@t0
F
BRK3
RRL
P2 Q2
230 kV Voltage support
Timed Fault Logic BRK2 Fault inception - 0.4 s and at 0.404 s
Fig.2. Two-area system model for a transient study.
Inrush Study: T3.3 Open the breakers #2 and #3. The transformer is energized on no load by closing the breaker #1. Close breaker 1 at 0.15s and observe the inrush currents. T3.4 Add a 1 Ohm resister in series with the 33 kV winding and observe the results. What effect does the resistance have on the decay of the inrush current? T3.5 Does the breaker closing instant influence the magnitude of inrush? Close the breaker at 0.1535 s and observe the current on phase A. T3.6 Enable the ‘single pole operation’ mode of the breaker. Close the poles at instants when the voltage of the respective phase is at a maximum. Observe results. T3.7 What situation would cause the transformer to saturate on both halves of a voltage cycle? Save the case!
The case should be saved as T_03_b.psc before proceeding.
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Line Energizing Study: T3.8 Close breaker # 1 and open breaker # 3. Include the multiple run component to control the operation of breaker #2 which is initially open. The closing instant B1 derived from the multiple run.
Fig.3. Multiple run component for breaker control. T3.9 The breaker closing instant (B1) should be changed for each run. The breaker is opened 0.15 s after its closing operation. Set the multiple run to switch for 10 sequential points on a 60 Hz waveform. Record the peak voltage E1 at the receiving end. Save the case! The case should be saved as T_03_c.psc before proceeding. Lines on the same right of way: A 130 km transmission line connects the Generating Station C and Station A. This line runs parallel to the 55 km line between Station A and the Wind Farm for 20 km from Station A. The generating voltage is stepped up to the transmission level through an 11/230 kV, Y-Y bank. T3.10 Extend the model to include the 130 km line and the generator as shown in figure 4. The transmission lines are arranged in a sub page as shown in figure 5. Save the case!
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Station C 11/230 kV, 500MVA Z=0.08 PU
RRL
RL
#1
#2
Zpos = 0.01 Ohms at 89 deg. Zzero = 0.011Ohms and 80 deg.
Line_03
BRK3 T lines
Timed Breaker Logic Closed@t0
Three Phase RMS Voltage Meter
Timed Breaker Logic Closed@t0 GT230
Line_01 Line_02 Line_03
BRK2
3 Phase RMS
230 kV Voltage support Cap. Bank
BRK3 I1
E2
BRK4 F
Line_01 Line_02
Ph
E1
BRK2
I4
60.0 V
E4
Timed Fault Logic
Fig.4. Three area system 1 Line_01
Line_02
Line_01 Line_02
Line_03
Line_03
Fig.5. Line arrangement inside the sub-page. T3.11 The voltage behind the equivalent source impedance of the voltage source representing the 4 generators at Station C is 12 kV at 21 degrees. T3.12 Use the Mathcad worksheet to verify results. T3.13 Change the configuration of the 11/230 kV transformer to represent a D-Y unit. Adjust the 11 kV source angle to reflect this change.
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Tutorial 4 – Wind Generator model and a Soft Start mechanism for the Generator. T4.1 Create a folder called c:……/PscadTraining/T_04. Save the case T_03_c.psc as T_04_a.psc. The wind turbines in the wind farm are driving induction generators operating at 33 kV. The total MVA of the station is 100 MVA. Replace the equivalent source with a detailed model of an induction generator. Assume all generators at the wind farm are operating under identical conditions. The induction generator connection is shown in figure 1. External rotor resistance
+
Rrotor
Rrotor +
DIST
Rrotor +
Rrotor
Wind...
TIME
0
0
1.0
WIN
P1
A
StoT
Q1
P
ohm
Rrotor
Power Q B
10
W S
IM
Iabc
StoT
a TL
-0.8 -0.5
A
TIN Ctrl = 1
B Ctrl
340 [uF]
DIST
Fig.1. Induction generator.
T4.2 Close breaker #1 at 2 s. Keep all other breakers closed. Assume the machine speed is at 1 pu before closing breaker A. Has the power flow changed? T4.3 Calculate the value of the shunt capacitance required to maintain the original power flow. See Mathcad calculations. Lower the time step to 25 us. T4.4 Will the system be stable if a sudden wind gust causes the input torque to the machine to increase by 60% (or 80 %)?
Save the case! The case should be saved as T_03_b.psc before proceeding.
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T4.5 Discuss how a small wind generator maybe connected to the system. Using BRKA appropriately, connect the wind generator to the system at 1 s. T4.6 Note the line currents on the system side when the wind farm is connected to the system. Change the initial speed of the machine to 0.6 pu and re run the simulation. Note the current transients. A Soft Starter shown in figure 2 is used to limit the starting currents when connecting the induction generators to the system. The back to back thyristors are used to control the voltage applied to the machine while its speed builds up. The firing angle characteristics are given in the table in the file ‘softstart.txt’. Model the circuit shown in figure 2. The firing controls for the thyristors are shown in figure 3.
2
1
FP1
T
[Windfarm] ANG
ANG BRK_SW
T 2
FP3
2
FP2
1 BRK_SW
T
TIME
BRK_SW
T A ANG
2
FP5
2
FP4 180.0
Ctrl = 1
B
T
Ctrl
ANG1
BRKA BRK_SW
T 2 FP6
Ea
BRKA NA
Eb Timed Breaker Logic Open@t0
BRKA
NB
Ec
Fig.2. Soft Starter.
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THYRISTOR FIRING PULSE CONTROL CIRCUIT
ANG_2 ANG_1
2 FP1
D
Vc Ec
+
ANG_1 theta
D
2 FP4
Vb Ec
+
H L
+
2 FP6
F
180.0
180.0 Va Eb
PLL
ANG_3
H L
+ F
2 FP2
180.0
Vb Eb
2 FP5
H L
Va Ea
L
2 FP3 ANG1
ANG_2
F
L
ANG1
ANG1
D + +
H
H L
ANG_1
ANG_3
H
Va Ec PLL
ANG_2 theta
Vc Ea
Vb Ea
PLL
ANG_3 theta
Vc Eb
Fig.3. Firing controls. T4.7 Observe the starting currents with and without soft start.
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Tutorial 5 – Including a machine model in a simulation. T5.1 Create a folder called c:……/PscadTraining/T_05. Save the case T_04_c.psc as T_05_a.psc. T5.2 Use the methods discussed in the supplementary exercises to replace the 11 kV source model with a detailed hydro generator model. T5.3 Enter the ratings of the machine to reflect the 500 MVA, 11 kV unit. (This may represent a number of identical units operating in parallel). T5.4 Include the generator controls in the simulation. T5.5 The voltage magnitude and the phase angle of the 11 kV source are used to initialize the machine. Observe the power flow and explain the reasons for minor differences. T5.6 Try using suitable control methods to adjust the machine power flow to the original values. T5.7 How do we model a thermal generator?
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Tutorial 6 – Doubly fed induction machine model. T6.1 Create a folder called c:……/PscadTraining/T_06. Load the library file dqo_new_lib.psl. Load the cases T_06_a and T_06_b.psc given to you with the course material. Save this file in your T_06 folder. T6.2 Understand the basic concept of the double fed connection. T6.3 Identify the role of different control blocks in the model. T6.4 Are all models in the control system found in the master library? Can the user define custom components and use then along with standard models from the master library? T6.5 Verify the operation of the two cases.
D + Va C Isa
* 0.037
alfa D + Vb C
Isb
* 0.037
Isc
* 0.037
1 sT
A
D + Vc C
Valfa
B 3 to 2 Transform beta Vbeta C
1 sT
phisx sT G 1 + sT
X
mag r to p
Y Y
sT G 1 + sT
X
Vsmag
phsmag
phi phis
phisy
Stator flux vector slpang alfa Rotor to Stator Q beta D
A alfa 2 to 3 B Transform beta C
Ira_ref Iraa Irb_ref Irbb Irc_ref Ircc
Rotor reference currents
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Transient Recovery Voltage Across Breaker Poles (TRV)
Prepared by: Date: August Revision: Date:
Dharshana Muthumuni 2005 2 Feb 16, 2007
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Breaker TRV Studies - Tutorial 1
Objective: Fundamental aspects of Breaker TRV Selection of time step Influence of stray capacitance Influence of loads and losses (resistance) IEEE defined breaker capability curves TRV under fault and normal switching conditions and use of multiple run T1.1 Open the case T_03_a.psc that was completed in Tutorial 3. Rename this as T_03_a_trv.psc. Keep breakers #1, #2 and #3 closed and the capacitor banks open. Run the case and make sure the power flow is as expected. T1.2 Apply a three phase fault to ground at 0.4s. The duration is 1s. T1.3 Open breaker #3 at 0.44 s. Observe the voltage across the breaker poles. T1.4 Discuss the reason for TRV. Now lower the time step to 2 us and observe the results. This will make clear that for TRV studies, a small time step is necessary.
20
TRV_ENV(+)
TRV_ENV(-)
Ea
10
0
-10
-20
-30 0.0200
0.0220
0.0240
0.0260
Fig.1. Breaker TRV and the IEEE TRV limits ... 0.0280 0.0300 0.0320 0.0340 ... ...
T1.5 In TRV studies, the stray capacitances near the breaker must be modeled adequately. How do we determine these values? T1.6 IEEE standards (IEEE C37.011) define the TRV capability curves for different breakers. These limits depend on a number of factors.
Breaker voltage rating
Fault current rating
Actual fault level
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Open the two PSCAD included with the course material. The two cases are TRV_Case_01.psc and TRV_Case_02.psc. TRV_Case_02.psc is from a low voltage distribution system of a utility in Florida. It was used to identify TRV issues and to identify corrective measures. T1.7 Observe how the IEEE TRV limits are simulated. T1.8 What are the measures available to reduce TRV levels?
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Large Industrial Loads – Induction Motor Transients Objectives: Induction motor starting Motor data Voltage dips and fluctuations - Flicker Motor starting methods Motor load types Soft starting Reading data from external files Control blocks Power electronic switches
Prepared by: Date: Revision: Date:
Dharshana Muthumuni August 2005 2 Feb 16, 2007
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Induction Machine Dynamics/Transients - Tutorial 1 T1.1 Connect a 13.8 kV, 15 kA induction motor to an infinite bus through a transformer and a breaker. The infinite bus voltage is 66 kV.
A P Power Q B
Pmot Qmot
W
0.0
IM
S
0.0
#1
#2
Is BRK
0.001
TL TIN 13.8 kV,2.2 kA motor 50.19 MVA, Inertia(J)= 2.2 pu
W
*
BRK
TIN
W
T1.2 The load torque applied to the motor is related to the motor speed. Derive a control block that will generate a torque signal that is proportional to the speed. (TIN = k*w) T1.3 The motor is to be switched on to the supply using a breaker. Use a ‘two state’ switch to send a signal to the breaker. T1.4 Observe the starting characteristics. Plot the line current, speed, Electric and mechanical torque and the terminal voltage at the machine. T1.5 What could cause the motor be driven into a generating mode. T1.6 Load the case ind_motor_starting_01.psc. This case models the loads of an industrial plant. Identify different components in the model. T1.7 Note the voltage dip during motor starting. Is this a power quality concern? T1.8 What methods can be employed to limit starting transients? T1.9 What could cause the motor be driven into a generating mode.
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T1.10 Induction motor transients can lead to serious power quality issues. The simulation example in case ind_motor_starting_01.psc illustrates the voltage dips seen by the other loads connected to the transformer. Load and run this case. a) Does additional rotor resistance affect the starting transients? b) See the effect of rotating inertia and mechanical damping on the transients. c) What are the typical loads types (characteristics) that are encountered in industry applications? T1.11 Load the case ind_motor_starting_02.psc. Note the load torque profile. Observe the voltage variation at the load terminal.
T
2
1
FP1
BRK_SW T 2
FP3
T
2
FP2
BRK_SW T 2
FP5
T
2
FP4
BRK_SW T 2
FP6 BRK a1
A
b1
B
c1
C
Ea Eb Ec
a2 b2 c2
Fig.2. Soft starter T1.12 Soft starting methods such as that shown in Fig 2 are used to limit the starting current of large induction machines. Discuss the current limiting mechanism of this scheme. Load the case ind_motor_starting_03.psc. a) What is the role of the PLL? b) How are signals transmitted from the main page to the sub page? c) Can PSCAD read data from external files? List a few applications where this can be useful? Verify the operation of the soft switch.
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Fast Front Studies Lightening Strike Objectives: Representing stray capacitances Representing arresters Representing Bus-bars Representing long lines Positioning of Arresters
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Dharshana Muthumuni August 2005 2 Feb 16, 2007
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Fast front studies - Tutorial 1
T1.1 The circuit shown below represents the arrangement of a transformer sub-station. This model is used to study the over voltages at a transformers terminal during a lightning strike on a station bus bar.
0.0003
0.0003
0.0006
TA1
TA1
1
bYC1
1
bYC1
Va
bYC1
1
bYC2
bYC2
Vtf
bYC2
350.0
350.0
TA1
350.0
10 m Station Bus
1
0.0027
1
0.0027
90 m Station Bus 1
0.0027
0.0006
0.0006
1 km Transmission Line
0.0003
Stray capacitance of equipment
Stray capacitance of equipment
P Approximate surge impedance line termination
Steep Front Surge Arrester N
Bx
B +
e
Bx
* 1.02
*
Lightning Current
F
To account for the fundamental frequency voltage component, the dc source is set to peak ac volts.
0.5
e TIME
Winding Capacitance for 220 kV Autotransformer (approximate)
ABB EXLIM Surge Arrester 192 kV
Simple Lightning Surge 1.2*50 Usec: I = 1.02*I1 * [ EXP(-13000 * t) - EXP(-4.4E6 * t) ]
Fig.1. Circuit for lightening study T1.2 Identify different components of the model T1.3 How do you represent the transformer? Where do you obtain the data? T1.4 How are transmission lines and cables represented for the purpose of this study? Can we justify this representation? T1.5 Does the position of the arrester have an impact on the over-voltage at the transformer? Place the arrester at the transformer terminal and observe the over-voltage. T1.6 What does the dc source represent? T1.7 How do we model the lightening surge? How do we define parameters for the surge?
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Ferro-Resonance Investigation
Objectives: Transformer parameters Saturation Selection of the simulation time step
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Dharshana Muthumuni August 2005 2 Feb 16, 2007
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Ferro-resonance - Tutorial 1
T1.1 Open the case ferroresonance.psc. This case is used to study a ferro resonance event during a breaker malfunction. 30MVA Distribution Transformer 230kV/13.2kV, Delta/Wye-Gnd Ztx=7.65%
System Equivalent Source Representation 3 Phase Eq. Source with z1 and z0
VbusA
A B C
A LINEA
VbusB
B
COUPLED PI SECTION
A B
LINEB
VbusC
C
C
VPriA VPriB VPriC
A B C
A
30 [MVA] #1 230.0
#2 13.2
B C
VSecA VSecB VSecC
LINEC 230 kV, 20 mile Transmission Line
BRKA
0.0015 BRKB
0.0015
1.5mH Outrush Reactor
0.0015 BRKC
50 MVAr @ 230kV
LINEA
LINEB
2.51
2.51
2.51
LINEC
Timed Breaker Logic Closed@t0 Timed Breaker Logic Closed@t0
Disable saturation and re run Timing for Line Breaker Phase A: Closed (stuck) Phase B: Opens at 100mSec Phase C: Closed (stuck)
Secondary Load Output Voltages
0.350 [MW]
Timed Breaker Logic Closed@t0
Fig.1. Circuit for Ferro resonance Case Study T1.2 Check the data entry for transformer saturation. What do different entries represent? T1.3 Include transformer losses. Do you see a change in results? T1.4 Open the capacitor banks. Are the results different? T1.5 Change the line length and observe the results? T1.6 What effect does the load have on the over voltage transients? T1.7 Are the transients sensitive to the transformer core characteristics?
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Faults and Current Transformers and Relays
Prepared by: Date: Revision: Date:
Dharshana Muthumuni August 2005 2 Feb 16, 2007
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Faults and Current Transformers and relays - Tutorial 1 Objective Getting familiar with models related to fault simulation. Getting familiar with different CT models.
T1.1 Create a new case by using either the Menu or Toolbar. A new case should appear in the Workspace settings entitled noname [psc]. Right-click on this Workspace settings entry and select Save As… and give the case a name. NOTE: Do not use any spaces in the name! Create a folder called c:……/PscadTraining/Faults. Save the case as case01.psc T1.2 Open the main page of your new case. The single line diagram shown below is a part of a substation feeding a shunt reactor. The reactor is modeled in two parts to enable a falut at point B, inside the turns. The component data is as shown. (make the transformer losses zero to limit the number of nodes if using the student version) Station 115 kV bus
Short line RL
RRL
#1
#2 0.005
Ea
Y-D Transformer Z = 8% Full load loss = 0.3% No load loss = 0.5%
Station 13.8 kV bus
Ir2
IL
REACTORS
EL
115 kV,50 Hz Source Z+ = 1.1Ohms / 88 deg Z0 = 2 Ohms / 86 deg
0.1
Ir1 0.0125
B
0.0125
A
You may use the wire mode to connect different components. T1.3 Build the case in PSCAD and enter the component data. T1.3 Plot the current IL and the voltage EL. T1.4 Use the ‘fault component to simulate a phase A to ground falut at location A at 0.1s.
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Timed Fault Logic T1.5 Observe the fault curent, IL. What is the reason for the presence of the initial DC exponential component? T1.6 What affects the rate of decay of the DC components. Change the resistance of the short line to 1 Ohm and observe the results. T1.7 Does the instant of the fault inception have an effect on the DC offset.? T1.8 What negative impacts can the DC offset have on the system protection.? T1.9 Connect the phase A line current at point A to the CT model as shown below. The CT ratio is 5:400. The CT burden is 0.15 Ohms in series with 0.8mH. Plot the secondary current and the flux density. IL1 Burden resistance 1 and 0.1 Ohms
T1.10 Increase the burden resistance to 4 Ohms and observe the results. Note the half cycle saturation effects due to the dc offset in the primary current. T1.11 The reactor is protected by a differential relay scheme. Use the 2-CT model in PSCAD to connect one phase of the reactor protection scheme. Ir11 Ir21
T1.12 Verify the burden current in the differential CT connection for faults at A and B. T1.13 Does the impedance of the connection leads have an effect on the results.? How is this impedance accounted for.? T1.14 Open the case ftdiff.psc. Check the performance of the differential relay during transformer energization.
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Faults and Current Transformers and relays - Tutorial 2 Objective: Getting familiar with models in the ‘Relay’ section of the master library. T2.1 Create a new case by using either the Menu or Toolbar. A new case should appear in the Workspace settings entitled noname [psc]. Right-click on this Workspace settings entry and select Save As… and give the case a name. NOTE: Do not use any spaces in the name! Create a folder called c:……/PscadTraining/Faults. Save the case as case02.psc T2.2 Open the main page of your new case. Construct the simple two area system shown in the diagram. The voltage sources are set to 230 kV. The inputs to the page module ‘Relay’ are all real data inputs. 0.1
0.1
I1 E
8.0
0.08
2.0
ABC->G
0.02
Timed Fault Logic
Ic
I1
1
2 Ia
Ic
3 Ib
Ic
Ib Ib
E
Ia
1 Ea
Ia
Relay
Expand this page to view the relay components
Ea Ea
T2.3 Use the modules in the ‘relay’ section of the master library to construct a simple distance relay. The different modules are shown below.
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FFTto extract the fundamental
FFT Ea F = 60.0 [Hz]
FFT Ia F = 60.0 [Hz] Ia B
FFT
+ IbD
+
+ F Ic
F = 60.0 [Hz]
Mag (7) 1
Impedance calculation
Ph (7) 1
EaM
dc
EaP
Mag (7) 1 Ph (7) 1
IaM
dc
IaP
VM EaM VP EaP IM IaM IP IaP I0M I0M I0P I0P
Va Ia+ kI0
R X R N X 376.99
N/D D
Mag (7) 1 Ph (7) 1
I0M
dc
I0P
R X
Ia Ib
R
21
X Mho Characteistics
Ic Ea
T2.4 Identify the function of each module. T2.5 Verify the operation of the relay.
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Power Quality
Electric Arc Furnace Model
Prepared by: Wang Pei Date: February 2007 Revision: Date:
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Electric arc furnace model The developed EAF model is based on the non-linear differential equations as outlined in [1], which models the non-linear characteristics of the electric arc as pictured in Fig. 1a. The equations representing the arc voltage (v) to arc current (i) are shown below, where r is the arc radius: dr n k 2 k 1 r k 2 r dt r m32 i v
k r
3 m 2
i
The parameters ki, r and n characterize the arc under a given operating condition. In reality, this V-I characteristic shows much more “noise” due to the unpredictable and chaotic nature of the load. Fig. 1b shows a more realistic EAF V-I characteristic.
(a) Ideal
(b) Actual
Fig. 1 Ideal and actual V-I characteristic of an EAF Arc Data Setting: Parameters k1 to k3 can be selected to obtain the EAF settings, such as active power, reactive power and power factor close to what were measured in the practical system. As the EAF model is sensitive to the system connected, parameters k1 to k3 may need to be re-tuned if the system configuration changes. The EAF model is designed to be able to take the inputs parameters as variables so the optimization routines of PSCAD can be used to expedite the process. Modulation Type setting: The randomness feature of the EAF model is simulated by adding certain sinusoidal and Gaussian noise. The magnitude/frequency of sinusoidal modulation and the standard
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deviation of Gaussian function can be specified. Each phase can be independently controlled.
It is important to note that it is impossible to get a simulation case to match the observed results perfectly due to the nature of the problem. The important thing is to capture the essential features and the trends of a practical arc furnace. Reference: [1] “A Harmonic Domain Computational Package for Non-Linear Problems and its Application to Electric Arcs,” E. Acha, A. Semlyen, N. Rajakovic. IEEE Transactions on Power Delivery,Vol 5, No.3, July 1990.
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FACTS DEVICES
Active Filters Instantaneous Reactive Power Method Synchronous Reference Frame Method
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Facts Devices - Tutorial - l Objective: Getting familiar with power electronic firing models Getting familiar with control system building block models Active filter theory
T14.1 Open the two PSCAD cases provided with the course material. The two cases are: Activefilter_SRF.psc Activefilter_IRP.psc They are located in the folder named ‘Active_filter’ T14.2 The main loads on both these case produce significant harmonics. Study the different models used in the control circuit for the variable speed drive in Activefilter_IRP.psc. T14.3 Study the control technique used in both IRP and SRF methods. T14.4 Study how the current reference PWM is implemented to in the active filter bridge. What is the function of the interpolated firing pulse module?
0.002 1 2 3 4 5 6
(1) H_on
6
H (2)
2
2
G11
G21
ON 6
H_off
6
6
L
(3)
H (4) OFF L
(5)
(6)
2
2
2
2
G31
G41
G51
G61
Fig.1. Integrated firing pulse module T14.5 Change the parameters of the filters in the control circuit of the active filter and see the change in response. Can we use FFT to extract the frequencies of interest?
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PSCAD BASIC TRAINING
Synchronous Machines Exercises 1 - 2
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Dharshana Muthumuni August 2005 2 Feb 16, 2007 47 / 72
Exercise 1 One machine infinite bus case E1.1 Open the case case_01_startup.psc. Timer
3 Phase RMS
LRR Timer S2M
IF
V
EF
A
B
Iffb
B
C
Iffc
C
60.0
Ph
Tm
Iffa
A
Te
A
B
HydroGener
F
0.01
C
Ef0 Ef If
17.32
w Tm Tm0 W
TM
0.495
E1.2 How do you start the machine as a ‘voltage source’. How do you switch from a ‘voltage source’ to a machine rotating at a fixed speed? How do you enable the rotational dynamics of the machine ?
E1.3 What are the functions of signals Ef0 and Tm0 of the synchronous machine model.
E1.4 Set the machine initial voltage magnitude to 1.04 pu and the phase to 0.75 rad.
E1.5 Run the case and note the Power and Reactive Power levels at steady state. Also measure the input torque Tm and the field voltage Ef at steady state.
E1.6 Start the machine in the normal ‘machine’ mode and observe the results.
E1.7 Use the steady state Tm and Ef values in E5.5 as inputs to Tm and Ef. Start the machine in the ‘machine’ mode. Observe results.
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Exercise 2 Initializing the machine to a load flow E2.1 Open the case Gen_Pqini_startmetds_01.psc. S/H in out hold
S2M
Vref0 Vref
3 Phase RMS
Exciter_(AC1A) VT Ef0 IT 3 Ef If
IF
EF
0.01
A
B
Iffb
B
C
Iffc
C
Te Tm
A
Iffa
B
C
Ef0 Ef If VT 3 IT A HydroGener
w Tm Tm0
TM
W
w
z
Hydro Gov 1 z0 Wref
Tmstdy
z
w
Tm
Hydro Tur 1 zi Wref
1.0
E2.2 Make sure the machine is rated at 150 MVA, 17.32 kV. It should be connected to an infinite bus rated at the same voltage through a transmission line of inductance 0.01 H. E2.3 Calculate the machine terminal voltage in PU and the phase angle in radians, if the steady state power and reactive power flow is 54 MW and 27 MVar respectively. E2.4 Set the machine initial conditions so that the simulation will give the correct steady state P and Q flow. E2.5 How are the governor, turbine and the exciter initialized? E2.6 Start the machine as a source and simulate the case. E2.7 Start the simulation with the machine in the normal ‘machine’ mode. What additional initial conditions are to be supplied to the machine?
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PSCAD ESSENTIAL TUTORIALS
Synchronous Machine Application Studies
Prepared by: Date: Revision: Date:
Dharshana Muthumuni August 2005 2 Feb 16, 2007
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Two area power system: Twoarea_system.psc This case shows two hydro generators connected through a tie line. When the system load changes, the tie line power is determined by the governor droop settings. Check if the machine inertia affects the results. Changes the droop settings to see the effects. Small signal stability: Ex_Smallsignal.psc Ex_Smallsignal_exciter.psc (The machine parameters and the system parameters are as given in the book, Power System Stability and Control by Prabha Kundur. The steady state P and Q values are 0.9 and 0.3 respectively. The oscillation frequency, upon a small disturbance is around 1 Hz and agrees with the Eigen Value calculation.)
These cases illustrate the oscillations in a system when a small disturbance is applied. The oscillation frequencies are in agreement with frequency domain Eigan value calculations. Does machine parameters affect the oscillation frequency? Does the machine inertia affect the oscillation frequency? Does the load flow condition effect the oscillation frequency?
Critical clearing time for faults: Ex_fault_exciter.psc Critical clearing time for this fault is 0.1 if the regulator gain is over 400. For values less than 400, the system becomes unstable. Try different fault clearing times and exciter gains to see how they are related. Power System Stabilizer: Ex_pss_tune.psc The system shown in this case is unstable if run without a power system stabilizer. Run the case with a constant field voltage and see if the system is stable. This will verify that the instability is due to the exciter action. Can we make the system stable by reducing the exciter gain? Design a power system stabilizer (PSS) to minimize the speed change upon a disturbance. Use the optimization method of PSCAD to design the PSS parameters.
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CONVERSION OF LOAD FLOW DATA FILES Direct Conversion of PSS/E Files for PSCAD Model Building
Prepared by: Pei Wang Date: Feb. 2006 Revision:
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Conversion of load flow dats files – Tutorial -1 Direct conversion of PSS/E files
Objectives: Getting familiar with building large systems in PSCAD Using E-TRAN to convert PSS/E data files Guidelines to determine detailed network for EMT study Validation of developed model
T1.1 Create two cases with E-TRAN for the IEEE 39 bus systems: one using only the .raw file and the other including the dynamic data .dyr file. - Practice with the selection of zone/area/bus/proximity/ - Network equivalences - Manual modifications required for EMT study purpose
Fig. 1.Single line diagram of IEEE 39 bus system
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T1.2 E-TRAN Runtime Library for PSCAD and custom substitution libraries - Series components (Tline/Transformer) and shunt components (generator) - Use of the sample substitution library EnabExc VREF VCT Enab Vref IEEET1
0.0 VS Ef0
Exciter VREF is loadflow terminal voltage... E VREF
0.9972 Volts(pu) 4.1825 Angle(deg) 632.0 / 1.0 Pout(MW) 109.911 / 1.0 Qout(MVAR)
VS
3 EF0 E VT EF IF 3IT G Ef If 1 + sT Ef0 A Ef If V E TE Te
1 VT
Vm G 1 + sT
E
GENROU Tm w Tm E Wpu TM
Initial Conditions from Loadflow
Tm0
G 1 + sT
TM0
W
TM TM0 IEEEG1
EnabGov
1.0
Enab E Wref WRef
Fig. 2: Detailed machine mode in the substitution library for EMT study T1.3 Method to determine the kept system (frequency scan)
Fig. 3 Frequency scan results at interested bus T1.4 Model verification. - Comparison of P, Q, V - Short circuit data 54 / 72
Converting a Solved PSS/E Case to PSCAD for Transient Simulations Many utilities have their power systems modeled in load flow programs. A great deal of effort is required to re-enter network data for transient simulation studies in Electromagnetic Transient (EMT) type programs. This application note describes the use a new tool that allows for an automated setup of PSCAD simulation cases by directly importing data from solved PSS/E load flow cases, thus maximizing the simulation engineer productivity. Some helpful tips are also provided on how to ensure the validity of the transient study by effectively selecting the size of the subsystem to be simulated in PSCAD. Some key points addressed here are:
Direct conversion of the PSS/E file: Basic steps
E-TRAN Runtime Library for PSCAD and E-TRAN custom substitution libraries
Network equivalences
Guidelines to determine the extent of the network to be modeled in detail
Model validation
Importing dynamic data from the PSS/E *.dyr file
The IEEE 39-bus system (see Figure 1) is used as the base case to illustrate the PSS/E to PSCAD conversion process. The IEEE 39-bus system is a standard system used for testing new power systems simulation methodologies. It was created based on a simplified model of the New England power system. The 39-bus system has 10 generators, 19 loads, 36 transmission lines and 12 transformers. The conversion of the system into PSCAD is achieved through E-TRAN, a program developed by Electranix Corporation. In addition to converting PSS/E data into PSCAD cases, this program offers many powerful features that could be manipulated by the simulation engineer to reduce the time spent on a study. The software’s most relevant features are outlined in this document.
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BUS29 T E_26_29_1
A V
GEN 6
BUS24
T E_16_24_1
VBUS27 100.0 P,Q 25.0 E Load
VBUS35
T E_16_19_1
VBUS17
BUS17
100.0 P,Q 25.0 E Load
VBUS15
P = 535.2 Q = 164.5 V = 1.018
A V
P = 662.4 Q = 133.8 V = 1.007
VBUS34
BUS13
E
E
T-Line Line1
T-Line Line1
VBUS13
VBUS31 BUS10
VBUS10 230.0 : 230.0 1 E BUS32
Slack Bus
VBUS32 A V
GEN 2
P = 697.9 Q = 226.8 V = 0.9918
P = 529.7 Q = 235.7 V = 0.9961
GEN 7
A V
A V
230.0 : 230.0 1 E
230.0 : 230.0 1
BUS31
BUS36
VBUS36
GEN 5
BUS11
VBUS11
100.0 P,Q 25.0 E Load
BUS9
E
T E_8_9_1
100.0 P,Q 25.0 E Load
T E_9_39_1
100.0 P,Q 25.0 E Load
100.0 P,Q 25.0 E Load
BUS8
230.0 : 230.0 1 E
T E_6_11_1
BUS7
VBUS8
100.0 P,Q 25.0 E Load
VBUS12
GEN 4
230.0 : 230.0 1 E
E
BUS12
T E_6_7_1
T E_7_8_1
230.0 : 230.0 1
T-Line Line1
BUS6
VBUS33
VBUS23
BUS34
T E_13_14_1
VBUS6 T E_5_8_1
VBUS9
BUS33
VBUS20
E
VBUS5
100.0 P,Q 25.0 E Load
BUS20
Load E 25.0 P,Q 100.0
BUS5
VBUS1
E
VBUS14 T E_4_5_1
BUS23
230.0 : 230.0 1
E
BUS14
T E_22_23_1
100.0 P,Q 25.0 E Load
VBUS19
T E_4_14_1
VBUS39
T E_21_22_1
BUS19
T E_14_15_1
100.0 P,Q 25.0 E Load
BUS39
BUS22
VBUS21
230.0 : 230.0 1
100.0 P,Q 25.0 E Load
VBUS3
VBUS22 BUS21
BUS15
T E_3_4_1
VBUS4
T E_1_39_1
T E_16_21_1
T E_15_16_1 T E_16_17_1
BUS4
BUS1
100.0 P,Q 25.0 E Load
A V
VBUS16
E
T E_3_18_1
BUS3
T E_1_2_1
T E_17_27_1
T E_17_18_1
230.0 : 230.0 1
100.0 P,Q 25.0 E Load
T E_2_3_1
P = 743.8 Q = 114.2 V = 1.029
BUS35
BUS16
VBUS2
GEN 1
VBUS24
A V
E
BUS27
VBUS18 BUS18
100.0 P,Q 25.0 E Load
T E_2_25_1
230.0 : 230.0 1
BUS2
GEN 9 T E_23_24_1
100.0 P,Q 25.0 E Load VBUS28
A V
T E_26_27_1
100.0 P,Q 25.0 E Load
VBUS26
P = 681.8 Q = 235.6 V = 1.059
A V
T E_25_26_1
100.0 P,Q 25.0 E Load
E BUS25
VBUS37
VBUS25
VBUS38
VBUS29
P = 573.7 Q = 101.5 V = 0.06819
P = 551.2 Q = 22.96 V = 1.04
100.0 P,Q 25.0 E Load
BUS26
230.0 : 230.0 1
P = 253.9 Q = 163.6 V = 1.052
BUS38 T E_28_29_1
BUS30
VBUS30
A V
BUS28 T E_26_28_1
BUS37
GEN 10
P = 975.2 Q = 54.56 V = 1.026
230.0 : 230.0 1 E
GEN 8
GEN 3
Figure 1 Single line diagram of the IEEE 39 bus system in PSCAD Converting the base PSS/E Case to PSCAD When converting a case from the PSS/E load flow data file (*.raw) and dynamic data file (*.dyr), E-TRAN allows for several options that provide enhanced flexibility to the final user. To convert the *.raw/*.dyr files, start the E-TRAN program. The pop-up dialog will prompt the user through the conversion steps (see ¡Error! No se encuentra el origen de la referencia.). The user will have to specify the location of the *.raw/*dyr data files and the target *.psc file. In the next dialog, the user will specify if the entire network is to be ‘kept’ or if only a specific part is kept and the rest equivalenced. In most transient studies there is no added benefit in modeling the details of the network beyond a few buses away from the location of main interest. E-TRAN allows for the system to be partially or fully converted (all its nodes) into PSCAD. .
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Figure 2 E-TRAN dialog boxes
The conversion process will generate a PSCAD (*.psc) file in the specified location. The network equivalent sources will have their magnitudes and phase angles automatically set for the same power flow as in the original PSS/E file.
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E-TRAN Runtime Library for PSCAD The E-TRAN Runtime Substitution Library (see Figure 3) contains a series of models specially developed for PSS/E-PSCAD conversions that translates PSS/E component information into equivalent PSCAD component information. The E-TRAN Runtime Substitution Library is provided with the program and contains the models that will appear in the converted PSCAD case. To run the converted PSCAD case:
Open PSCAD
Load the E-TRAN Runtime substitution library
Load the PSCAD case
Verify the load flow results
Figure 3 E-TRAN Runtime library for PSCAD
Custom Substitution Libraries and data entry Load flow programs represent the power system network using simplified models consisting of resistances, inductances and capacitances. When converted to a PSCAD case, these components can be replaced by more detailed models to represent the respective unit. Therefore, depending on the user needs, some of the models automatically substituted from the E-TRAN substitution library may require additional data or may have to be replaced by more complex models from the PSCAD master
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library. Fortunately, E-TRAN allows the user to create a user substitution library where any additional information will have to be entered by the users only once, when the component is used the first time. An example that calls for the use of the custom substitution library could be a transmission line, where the PI section or the Bergeron models used to represent it may have to be replaced by a more accurate frequency dependant model, which will require specific information on the tower, conductor and right of way dimensions. In the custom substitution library the user can predefine the substitution of a specific system component to be done with a pre-filled out PSCAD master library component (or a user built component) by referencing to the bus number they are connected to (see Figure 4) E
~
Source1 Syncronous machine at bus 159
T B_456_ B_822_T1
A detailed frequency dependant TLine From bus 456 to bus 822, Circuit T1
Figure 4 Examples of ‘custom substitution library’ components “You can save detailed device data in this library, and E-TRAN will use this data (substituting it for the simple load flow data) every time a region of the network is converted into PSCAD. The goal is to eventually have all detailed model data entered into this library. Once this is achieved, this library can be used to generate PSCAD cases for any location of your system. The models in the Substitution Library can also be custom written components, or even page components. A page component can also have as many layers of sub-pages as required. Each page can also contain sliders, plots, graphs, control-panels etc... When E-TRAN copies the data from your Substitution Library, it will also replace initial condition information. For example, E-TRAN will modify synchronous machine data to replace the data for the terminal voltage, angle, P and Q.”
The construction of the custom library will require a significant investment of time for large networks. However, once it is completed, you can convert any part of your network without having to do any manual data entry. This was identified as a key time saving feature by large utilities and consultants who are required to work on different parts of large networks when undertaking different projects.
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Deciding on the Part of the Network to be Kept A transient study would require the detailed modeling of a small part of the network around the main point of interest. Typically, this would be about 2 or 3 buses away from this point. E-TRAN allows the users to efficiently decide and check if the ‘kept’ network details are adequate for a given study. The following steps are recommended. This makes use of the ‘network frequency scan’ component of PSCAD (see Figure 5).
Convert the PSS/E file to PSCAD, keeping the details 2 or 3 buses away from the main point of interest and equivalencing the rest.
Use the frequency scan component of PSCAD to plot the impedance vs. frequency characteristic of this system at the bus concerned.
Reconvert the PSS/E file, this time, keeping the details of one more bus away than in the earlier step.
Plot the impedance vs. frequency characteristics of this system at the bus concerned and compare with the first plot.
Repeat the process until the differences in frequency characteristics are minor in the frequency range of interest. Adding more details of the network beyond this point is unlikely to improve results. Z(f)
0.0 2000 [Hz]
Figure 5 PSCAD Frequency Scan component
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Figure 6 Frequency scans 2, 3, … 6 buses away at bus No. 15 for the system under study
Figure 6 shows the use of the frequency scan feature. Here different network equivalents were constructed using E-TRAN for the IEEE 39 bus system at bus No. 15 for 2, 3, … 6 buses away (with 6 buses away comprising the whole network). These network equivalents were created using the load flow data file only (*.raw). It can be observed that the frequency spectrums of the equivalent networks start providing a good approximation for the whole network starting at ‘4 buses away’. Validation A quick method to validate the simplified equivalent system provided by E-TRAN is to compare the values calculated by PSCAD for node voltages, transmission line load flows or P, Q flows at generation busses with the ones previously calculated by PSS/E. For such purpose, use the multi-meter to display the voltage at the node of concern and the P and Q flows in the respective transmission line. Then, display the same information for such node in the PSS/E load flow utility. The converted PSCAD case will have auto generated labels that display the P, Q flows at generation buses. Figure 7 shows the PSS/E and PSCAD results for the voltage magnitude and angle at node 15 as well as the P and Q flows for the nodes 15 to 16 transmission line.
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PSS/E Load Flow output BUS
15
LBUS15
345
AREA
CKT 1
TO
16
LBUS16
345
1
1
MW
MVAR
MVA
%I
1.0154PU -7.75 DEG 350.31KV
-314.7 -151.7
349.3
P1 : ...
V15 Angle
V15_Ang
Z(f)
0.0 2000 [Hz]
LBUS15 N15
P = -314.7 Q = -151.7 V = 1.015 A V
-7.74857 T E_15_16_1
Figure 7 Comparison of load flow results between PSCAD and PSS/E
Short-circuit level calculation at certain buses for the converted PSCAD case is also recommended. The short-circuit results can be compared to those from the PSS/E study or utility system data for validation purpose. Once the PSCAD system has been validated, it is ready to be used for transient studies. Importing Dynamic Data from the .dyr File During the conversion process the user can specify to import dynamic data from the PSS/E *dyr file. If this option is selected, all generators in the ‘kept’ part of the network will be replaced by detailed machine models (see Figure 8). The machine controls and related models (exciter, governor, PSS, turbine) will also be included in the PSCAD model. All information necessary to initialize these models will either be imported from the *raw/*dyr files or be computed by E-TRAN. Thus, the simulation will automatically come to the specific steady state after a few cycles of simulation time.
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EnabExc VREF VCT Enab Vref IEEET1
0.0 VS Ef0
Exciter VREF is loadflow terminal voltage... E 0.9972 Volts(pu) 4.1825 Angle(deg) 632.0 / 1.0 Pout(MW) 109.911 / 1.0 Qout(MVAR)
VREF
VS
3 EF0 E VT EF IF 3IT G Ef If 1 + sT Ef0 A Ef If V E TE Te
1 VT
Vm G 1 + sT
E
GENROU Tm w Tm E Wpu TM
Initial Conditions from Loadflow
Tm0
G 1 + sT
TM0
W
TM TM0 IEEEG1
EnabGov
1.0
Enab E Wref WRef
Figure 8 Detailed synchronous machine model automatically generated by E-TRAN with parameters taken from the PSS/E *.dyr and *.raw files
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LBUS01 N1
T E_1_2_1
LBUS02 N2
T E_2_3_1
LBUS03 N3
T E_3_4_1
LBUS04 N4
500.0 P,Q 184.0 E Load
322.0 P,Q E Load 2.4 T E_3_18_1
T E_2_25_1
LBUS25 N25
T E_25_26_1
LBUS18 N18 LBUS26 N26
158.0 P,Q E Load 30.0 139.0 P,Q E Load 17.0
224.0 P,Q E Load 47.2 345.0 : 22.0 1 E 345.0 : 22.0 1 E T E_1_39_1
GBUS39 N39
T E_9_39_1
GBUS30 N30 VN30 LBUS09 N9
VN39
E 250.0 146.154
GBUS37 N37 VN37
~
E_30_0_1 LBUS08 T N8
E_8_9_1
540.0 0.445
E
~ E_37_0_1
P = 522 Q = 176 522.0 P,Q A 176.0 E Load V
1104.0 P,Q 250.0 E Load 1000.0 E 88.281
~
E_39_0_1
Figure 9 IEEE 39 bus system converted to PSCAD for bus No. 1 (3 nodes away) A subsequent validation document will discuss the conversion process in more detail. This will include a discussion on importing dynamic devices, saturation and comparison of low frequency transients with transient stability results. References [1] Electranix Corporation “E-TRAN V1.1: Electrical Translation Program for Power Systems. User’s Manual” February 2003 Prepared by: Juan Carlos Garcia Dharshana Muthumuni Pei Wang
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PSCAD ADVANCE TRAINING
Tutorial on Creating Custom Components
Prepared by: Date: Revision: Date:
Dharshana Muthumuni August 2005 2 Feb 16, 2007
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PSCAD Advanced Training - Tutorial 1 Adder Purpose: To get familiar with the Component Workshop (or the design editor). Create input/output nodes. Get familiar with the graphic, Parameters and the script sections of the editor.
Create a library file. Use the component workshop to create a simple control block to do the following computation.
K1 A K 2 B C A and B - External inputs K1 and K2 – Internal parameters C – Output Include the component in a case and verify its accuracy Modify the component so that K1 and K2 can be entered as variables. Verify the modified component.
A Adder
C
B
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PSCAD Advanced Training - Tutorial 2 Integrator Purpose: Calling external subroutines. Storing data for computations in following (future) time steps. The block should perform the following function y xdt
x – input y – output To keep things simple, use ‘rectangular integration’. y(t ) y(t t ) x(t ) t
This will require the storage of ‘past’ value of y. Allow for the input of initial value of y. Use an external FORTRAN Subroutine to do the calculations.
Integrator x
y
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PSCAD Advanced Training - Tutorial 3 Electrical Component – Transformer (coupled wires) Purpose: Design an ‘electrical’ component. Using ‘branch’ and ‘transformer’ sections of the ‘script’
Design a model of two magnetically coupled wires. The model is to be interfaced with other electrical components in the master library. The inductances and resistances are the inputs. va La Mab d ia Ra o ia vb Mab Lb dt ib o Rb ib
Use the ‘transformers’ section to enter the L and R values. Connect the model to a source and verify the model. a1
a2
b1
b2
Two coupled wires with capacitance
Use the ‘Branch’ section to add ‘stray capacitance’ between the wires on the input side.
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PSCAD Advanced Training - Tutorial 4 Electrical Component – A simple DC Machine Purpose: Interface an electric component as a voltage source. (Branch based interface)
Design a simple model of a DC machine. Field circuit - Series L and R Armature circuit – A series branch of L, R and a voltage source of magnitude Eb. Eb k _ w w speed 150 k _ 1 e if / kf 188 .5 if – Field current kf – Input parameter (constant) The inductances and resistances are the other inputs. f1
f2
a1 a2
Simple DC Machine w
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FORTRAN CODES Integrator: ! SUBROUTINE INTEGRATOR(x,y,YINI) ! ! Purpose - integration of a real signal ! Language - Fortran 77/90 ! Date ! Author ! ! Include Files ! ------------INCLUDE 'nd.h' INCLUDE 's1.h' INCLUDE 'emtstor.h' ! ! Variable Declarations ! --------------------REAL x,y,YINI REAL YOLD INTEGER ISTORF ! ! Program begins ! -------------! ISTORF = NSTORF NSTORF = NSTORF + 1 ! it is good to assign NSTORF to ISTORF and ! have all the user assigned STORx locations at the ! top, then you can even use the other functions ! available in EMTDC in your code without worrying ! about which STORx locations are ! used by them YOLD = STORF(ISTORF) ! here NSTORF points to the first STORF location ! used in the routine, in the old method in V2, NEXC ! pointed to the last STOR location in the previously ! called subroutine/function. Y = x*DELT + YOLD ! output at time zero IF (TIMEZERO) THEN Y = YINI ENDIF ! save the data for next time step STORF(ISTORF) = y ! RETURN END
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Simple DC Machine:
! !
SUBROUTINE SIMPLEDC(Kf,w,A1A2,F1F2,SS) ! Dharshana : 04 Aug 2002 INCLUDE 'nd.h' INCLUDE 's0.h' INCLUDE 's1.h' INCLUDE 's2.h' INCLUDE 'branches.h'
REAL Kf,Ifld,w,k_pi INTEGER A1A2,F1F2,SS
!
! !
Activate the source on branch A1A2 SOURCE(A1A2,SS)=.TRUE.
Read the field current and the armature current during the previous time step Ifld=CBR(F1F2,SS)*1000
! ! !
Define the noload excitation charactersitics for the machine k_pi = (150/188.5)*(1 -EXP(-Ifld/Kf))
! EBR(A1A2,SS)=-k_pi*w/1000 ! RETURN END !
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FAX Page 72 of 10
Urgent For Review Please Comment That concludes the Introduction to PSCAD and Applications course. Thank Please Reply you for your attention and participation. As you work with PSCAD in thePlease Recycle
future, please remember we are available to provide assistance with any simulation or modeling difficulties you may encounter. Please do not The information contained in this facsimile is strictly for the personal hesitate to contact us at: attention of the addressee.
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The Manitoba HVDC Research Centre Inc. accepts no responsibility for consequences arising from receipt of this facsimile by a party other than the addressee. If you have received this facsimile in error, please notify us immediately. Thank you.
As well, additional training courses are available, please refer to www.pscad.com for more information. We are also able to offer customized courses to suit your specific requirements. Please do not hesitate to contact us for more information at:
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