PSCAD Course Notes

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Introduction to PSCAD and

Applications

Training Course Presented by the Manitoba

HVDC Research Centre

Course Date:

Location:

Lead Instructor:

Manitoba HVDC Research Centre Inc.

244 Cree Crescent

Winnipeg, Manitoba, Canada R3J 3W1

T 204 989 1240 F 204 989 1277 [email protected] www.hvdc.ca

F A X

Page 1 of 10

Urgent For Review Please Comment Please Reply Please Recycle

The information contained in this

facsimile is strictly for the personal

attention of the addressee.

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.

2 / 72

PSCAD GETTING-STARTED

TUTORIALS

Getting Started and Basic Features

Prepared by: Dharshana Muthumuni

Date: August 2005

Revision: 3

Date: March12, 2007

3 / 72

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.

BRK

TimedBreaker

LogicOpen@t0

Ia

66 kV,60 Hz Source

Z+ = 3.9Ohms / 75.58 deg

Z0 = 14.95 Ohms / 80.46 deg

Y-Y Transformer

7.5 MVA

Z = 6.14 %

Full load loss = 0.3%

No load loss = 0.5%

No load current 1 %

#1

#2

BR

K

1e

6

E_66

66 kV BUS

RL

RR

L

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.

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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.

BRK

Main ...

BRK_Control

1

C O

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.

Capacitor

800 KVars per phase

40.94 [uF]

B_

mo

t

EN484Feeder

81m U/G

54m OH

PI

CO

UP

LE

D

SE

CT

ION

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

0.0

0.0

TIN

X2

W*

0.8 TIN

Em

ot

Mechanical Torque

This block models the mechanical

characteristics of a typical load.

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

B_mot

TimedBreaker

LogicOpen@t0

42.5 [uH]

Etrv

S TL

N

I M

W

0.001

Ib

R_C1R_C1

Main ...

R_C1

1

C O

12.47 kV BUS

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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28.0 wTm

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

X2

W*

0.8 TIN

Mechanical Torque

This block models the mechanical

characteristics of a typical load.

Capacitor leg

Capacitor

800 KVars per phase

40.94 [uF]42.5 [uH]R_C1

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PSCAD ESSENTIAL TRAINING

Tutorials 1 6

1. Initializing a simulation 2. Switching study 3. Transformers and inrush 4. Transmission lines 5. Power electronic switching 6. Induction machine dynamics 7. Synchronous Machines and controls 8. Wind farms and doubly fed machines


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.

RL

RR

L

RL

RR

L

P1

Q1

P2

Q2 Q2

0.0740.14

100 MVA Transformer

33/230 kV, Z = 0.1 pu

55 km line

230 kV

230 kV Eq. source

Station AWind Farm

Z_positive = 10 Ohms at 88

deg.

Z_zero = 7 Ohms at 82 deg.

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 re-compiled. (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.

R

LR

RL

P2

Q2 Q2

0.0740.14

Wind

Farma

Fig.2 Main page

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RL

RR

L

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 R

L

VF

Ph

RR

L

60.0

Main : Controls

250

220

V230

230

90

-90

0

10987654321

FTYPE

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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RL

VF

Ph

RR

LP2

Q2 Q2

0.074 [H]0.14 [H]

Wind

Farma

BRK1

TimedBreakerLogic

Closed@t0

BRK1

BRK2

TimedBreakerLogic

Closed@t0

BRK2

TimedFaultLogic

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

E1

I1

I1

E1 E1

BRK3

BRK3

TimedBreaker

LogicClosed@t0

60.0

Fault inception - 0.4 s and at 0.404 s

V

A

Main : Controls

250

220

V230

230

90

-90

Ph230

0

10987654321

FTYPE

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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I1

I1

I1

1 1 1

XA

XB

XC

Ph+

Ph-

Ph0

Mag+ Mag- Mag0

(31)

(31)

(31)

(31) (31) (31)

dcA dcB dcC

F F T

F = 60.0 [Hz]

2

1

2

3

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.

RL

VF

Ph

RR

L

60.0

230 kV

Voltage support

Cap. Bank

GT230

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

1.00E-06

1.00E-06

1.00E-06

1.00E-06

1 3 5 7 9 11 13 15 17 19

Series1

Save the case!


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. Re-strike 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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0.0

03

17

Outrush

Reactors

R1 R2

R2

R1

-79

.82

[MV

AR

]0

.08

01

3 [M

W]

R2

-3.9

88

e-0

05

[MV

AR

]0

.05

63

5 [M

W]

R3

-79

.7 [M

VA

R]

0.0

92

02

[MW

]

TimedBreakerLogic

Closed@t0

R3

-3.9

88

e-0

05

[MV

AR

]0

.05

63

5 [M

W]

R4

R4

TimedBreakerLogic

Closed@t0

MOV

kJoules

Imo

v

MOV

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. Use the frequency dependent phase model to represent the line.

30 [m]

10 [m]

C1

C2

C3

10 [m]

Ground_Wires: 1/2"HighStrengthSteel

Conductors: chukar

Tower: 3H5

10 [m]

0 [m]

5 [m]

G1 G2

Fig.1. 230 kV Transmission tower.

19 / 72

RL

VF

Ph

RR

L

P2

Q2 Q2

Wind

Farma BRK1A

BRK2

TimedBreakerLogic

Open@t0

BRK2

E1

I1

I1

E1 E1

BRK3

60.0

3 PhaseRMS

Three Phase

RMS Voltage Meter

Fault inception - 0.4 s and at 0.404 s

230 kV

Voltage support

Cap. Bank

GT230

TimedFaultLogic

BRK3

TimedBreaker

LogicOpen@t0

#1 #2

Line_01

Line_01

Line_01

I2

E2

BRK1C

TimedBreakerLogic

Open@t0BRK1B

TimedBreakerLogic

Open@t0

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!


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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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VF

Ph

BRK2

TimedBreakerLogic

Closed@t0

BRK2 E1

I1BRK3

60.0

3 PhaseRMS

Three Phase

RMS Voltage Meter

230 kV

Voltage support

Cap. Bank

GT230

BRK3

TimedBreaker

LogicClosed@t0

Line_01E2

T lines

Line_01Line_02

Line_03

Line_02

E4

I4BRK4

Line_03

#1 #2RL RRL

Zpos = 0.01 Ohms at 89 deg.

Zzero = 0.011Ohms and 80 deg.

11/230 kV, 500MVA

Z=0.08 PU

Station C

TimedFaultLogic

Fig.4. Three area system

Line_01

Line_01

Line_02

Line_02

1

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.

a

1.0WIN

S

TL

I M

W

Rrotor

Rro

tor

+R

roto

r

+

Rro

tor

+

A

B

Ctrl

Ctrl = 1-0.8

DIST

TIN

External rotor

resistance

Wind...

10

0

Rrotor

0

ohm

TIMEDIST

StoT

-0.5

Po

we

r AB

PQ

Iabc

P1Q1

StoT

34

0 [u

F]

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!


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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.

BRKA

TimedBreakerLogic

Open@t0

T

2

T

2

T

2

T

2

T

2

T

2

Ec

FP1

FP2

FP3

FP4

FP5

FP6

1

BRK_SW

BRK_SW

BRK_SW

Ea

Eb

BRKA

BRK_SWTIME 1

[Windfarm] ANG ANG

A

B

Ctrl

Ctrl = 1

ANG1

ANG

180.0

BRKA

NA NB

Fig.2. Soft Starter.

24 / 72

THYRISTOR FIRING PULSE

CONTROL CIRCUIT

FP1

FP2

ANG_1

L

H

2

L

H

2

18

0.0

D+

F

+

Va

Vb

Vc

PLLtheta

Ea

Eb

Ec

Va

Vb

Vc

PLLtheta

Eb

Ec

Ea

Va

Vb

Vc

PLLtheta

Ec

Ea

Eb

ANG_1

ANG_1

ANG_2 ANG_3

FP3

FP4

L

H

2

L

H

2

18

0.0

D+

F

+

ANG_2

ANG_2

FP5

FP6

L

H

2

L

H

2

18

0.0

D+

F

+

ANG_3

ANG_3

ANG1

ANG1 ANG1

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.

Vbeta

Vsmag

Vc

Va

Isc

C-

D+

Isb

VbC

-D

+

phisy

phisx

X

YY

r to p

X

mag

phiphsmag

GsT

1 + sT

ValfaG

sT1 + sT

1sT

1sT

phis

A

B

C

3 to 2 Transform

alfa

beta

*0.037Isa

C-

D+

*0.037

*0.037

Stator flux vector

Iraa

Irbb

Ircc

Ira_ref

Irb_ref

Irc_ref

slpang

to Stator

D

Q

Rotor

alfa

beta

A

B

C

2 to 3Transform

alfa

beta

Rotor reference currents

27 / 72

Transient Recovery Voltage Across

Breaker Poles

(TRV)


Date: August 2005

Revision: 2

Date: Feb 16, 2007

28 / 72

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.

Fig.1. Breaker TRV and the IEEE TRV limits

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

0.0200 0.0220 0.0240 0.0260 0.0280 0.0300 0.0320 0.0340 ...

...

...

-30

-20

-10

0

10

20 TRV_ENV(+) TRV_ENV(-) Ea

29 / 72

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?

30 / 72

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


Date: August 2005

Revision: 2

Date: Feb 16, 2007

31 / 72

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.

#1 #2Is

BRK 0.001

13.8 kV,2.2 kA motor

50.19 MVA, Inertia(J)= 2.2 pu BRK

*W

W

TIN

TIN

0.0

0.0

S

TL

I M

W

Po

we

r

A B

P Q

Pmot Qmot

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.

32 / 72

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

T

2T

2

T

2T

2

T

2

Ec

FP1

FP2

FP3

FP4

FP5

FP6

1

BRK_SW

BRK_SW

BRK_SW

Ea

Eb

C

B

A

BRK

a2

b2

c2

a1

b1

c1

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.

33 / 72

Fast Front Studies

Lightening Strike

Objectives:

Representing stray capacitances

Representing arresters

Representing Bus-bars

Representing long lines

Positioning of Arresters


Date: August 2005

Revision: 2

Date: Feb 16, 2007

34 / 72

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.

TA1

1

TA1

1

TA1

35

0.0

35

0.0

35

0.0

Lightning Current

eBx

eBx

TIME

B

-

F

+

Simple Lightning Surge 1.2*50 Usec:

I = 1.02*I1 * [ EXP(-13000 * t) - EXP(-4.4E6 * t) ]

bYC1

1

bYC1

1

bYC1

bYC2

1

bYC2

1

bYC2

0.0

02

7

0.0

02

7

0.0

02

7

Steep FrontSurge

Arrester

P

N

Winding Capacitance for

220 kV Autotransformer

(approximate)

*

ABB EXLIM Surge

Arrester 192 kV

0.5

Va Vtf

*1.02

10 m Station Bus90 m Station Bus

1 km Transmission Line

Approximate surge

impedance

line termination

0.0

00

3

0.0

00

3

0.0

00

3

0.0

00

6

0.0

00

6

0.0

00

6

Stray capacitance

of equipment

Stray capacitance

of equipment

To account for the fundamental

frequency voltage component,

the dc source is set to peak

ac volts.

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?

35 / 72

Ferro-Resonance Investigation

Objectives:

Transformer parameters

Saturation

Selection of the simulation time step


Date: August 2005

Revision: 2

Date: Feb 16, 2007

36 / 72

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.

2.5

1

2.5

1

2.5

1

BR

KC

VbusA

LINEA

LINEB

LINEC

BR

KB

BR

KA

VbusC

VbusBLINEA

LINEB

3 Phase

z1 and z0

A

B

C

Eq. Sourcewith

LINEC

System Equivalent

Source Representation

0.0

01

5

0.0

01

5

0.0

01

5

VSecA

VSecB

VSecC

VPriA

VPriB

VPriC

TimedBreaker

LogicClosed@t0

30MVA Distribution Transformer

230kV/13.2kV, Delta/Wye-Gnd

Ztx=7.65%

TimedBreaker

LogicClosed@t0

A

B

C

A

B

C

SECTIONPI

COUPLED

230 kV, 20 mile Transmission Line

A

B

C

A

B

C13.2

#2#1

230.0

30 [MVA]

Timing for Line Breaker

Phase A: Closed (stuck)

Phase B: Opens at 100mSec

Phase C: Closed (stuck)

TimedBreaker

LogicClosed@t0

50 MVAr @ 230kV

1.5mH Outrush Reactor

Output Voltages

Secondary Load

0.350 [MW]

Disable saturation

and re run

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?

37 / 72

Faults and Current Transformers and

Relays


Date: August 2005

Revision: 2

Date: Feb 16, 2007

38 / 72

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


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

Station 13.8 kV

bus

RL RRL

0.0125

Short line

EL

IL

Ea

Ir1Ir2

0.0125 AB

REACTORS

0.005 0.1

#1 #2

115 kV,50 Hz Source

Z+ = 1.1Ohms / 88 deg

Z0 = 2 Ohms / 86 degY-D Transformer

Z = 8%

Full load loss = 0.3%

No load loss = 0.5%

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.

39 / 72

TimedFaultLogic

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.

Ir1

Ir2

1

1

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.

40 / 72

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


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

8.0 0.08 2.0 0.02

ABC->G

TimedFaultLogic

I1

E

0.1

Relay

Ea

Ia

Ib

Ic

Ic

Ib

Ia

Ea

I1

E

1 2 3

1

Ia Ib Ic

Ea

Expand this page to view the

relay components

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.

41 / 72

VM

IM

I0M

VP

IP

I0P

R

X

Va

Ia+ kI

0

Mag

Ph

dc

(7)

(7)

F F T

F = 60.0 [Hz]

Mag

Ph

dc

(7)

(7)

F F T

F = 60.0 [Hz]

Mag

Ph

dc

(7)

(7)

F F T

F = 60.0 [Hz]

Ia

Ea

B

+

D+

F

+

Ic

Ib

Ia

1

1

1

1

1

1

EaM

EaP

IaM

IaP

I0M

I0P

EaM

EaP

IaM

IaP

I0M

I0P

N

D

N/D

376.99

R

X

R

X

R

X

21

Ia

Ib

Ic

Ea

Impedance calculation

Mho

Characteistics

FFTto extract the

fundamental

T2.4 Identify the function of each module.

T2.5 Verify the operation of the relay.

42 / 72

Power Quality

Electric Arc Furnace Model

Prepared by: Wang Pei

Date: February 2007

Revision:

Date:

43 / 72

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:

ik

krkrdt

drr

m

n 23

21 2

iv

r

km

2

3

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.

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

(b) Actual (a) Ideal

Fig. 1 Ideal and actual V-I characteristic of an EAF

44 / 72

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.

45 / 72

FACTS DEVICES

Active Filters

Instantaneous Reactive Power Method

Synchronous Reference Frame Method


Date: August 2005

Revision: 2

Date: Feb 16, 2007

46 / 72

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?

6

6

6

6

L

H

H

ON

OFF

L

(1)

(4)

(5)

(6)

2

2

2

(2)

(3)

2

2

2

0.002

1

2

3

4

5

6H_on

H_off

G11

G21

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?

47 / 72

PSCAD BASIC TRAINING

Synchronous Machines

Exercises 1 - 2


Date: August 2005

Revision: 2

Date: Feb 16, 2007

48 / 72

Exercise 1

One machine infinite bus case

E1.1 Open the case case_01_startup.psc.

A

B

C

EF

3 PhaseRMS

TM

LRR

S2M

Iffa

Iffb

Iffc

0.0

1

ABC

VF

Ph

HydroGener

w

Te

A

B

C

IfEfEf0 Ef If

Tm0Tm

Tm

17.32

60.0

Timer

Timer

IF

W

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.

49 / 72

Exercise 2

Initializing the machine to a load flow

E2.1 Open the case Gen_Pqini_startmetds_01.psc.

A

B

C

W

EF IF

3 PhaseRMS

TM

Tmstdy

1.0

S / Hinhold

out

S2M

VTIT 3

IfEfEf0

Vref

Exciter_(AC1A)

Vref0

w Tm

Wref

z

zi

Hydro Tur 1

w

Wrefz0

z

Hydro Gov 1

Iffa

Iffb

Iffc

0.0

1

ABC

HydroGener

VTIT

3

w

Te

A

B

C

IfEfEf0 Ef If

Tm0Tm

Tm

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?

50 / 72

PSCAD ESSENTIAL TUTORIALS

Synchronous Machine Application Studies


Date: August 2005

Revision: 2

Date: Feb 16, 2007

51 / 72

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.

52 / 72

CONVERSION OF LOAD FLOW

DATA FILES

Direct Conversion of PSS/E Files for PSCAD

Model Building

Prepared by: Pei Wang

Date: Feb. 2006

Revision:

53 / 72

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

54 / 72

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

Angle(deg)

Pout(MW)

Qout(MVAR)

4.1825

632.0

109.911

Initial Conditions from Loadflow

E

Volts(pu)0.9972

/ 1.0

/ 1.0

TE

Ef

Ef0

If

E

TM0TM

1 VmVT

Wpu

G1 + sT

G1 + sT

G1 + sT

E

Te

3

AV

Tm

Tm0

Ef0

Tmw

Ef If

E

GENROU

E

Enab

VTIT

3

IFEF

EF0

Vref

VSIEEET1

VCT

VREF

EnabExc

Exciter VREF

is loadflow terminal voltage...

VREF

0.0VS

E

TM0

Enab

W

Wref

TM

IEEEG1EnabGov

WRef1.0

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

55 / 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 softwares most relevant features are outlined in this document.

56 / 72

GEN10

GEN1

GEN2

GEN4

GEN5

GEN6

GEN7

8GEN

GE

N9

BUS30

BUS2

BUS37

BUS25

BUS31

BUS6

BUS34

BUS20 BUS33

BUS19

BUS35

BUS22

BUS38

BUS36

BUS23

BUS39

BUS1

BUS9

BUS8

BUS7

BUS5

BUS4

BUS3

BUS18

BUS26

BUS28

BUS17

BUS27

GEN3

BUS32

BUS10

BUS11

BUS12

BUS13

BUS16

BUS24

BUS21

BUS15

BUS14

BUS29

VBUS5

VBUS26

VBUS28

VBUS15

VB

US

17

VBUS16

VBUS14

VBUS21

VBUS24

VBUS1

VBUS9

VBUS8

VBUS31

VBUS30

VBUS2

VBUS37

VBUS25

VBUS6

VBUS39

VBUS12

VBUS11

VBUS13

VBUS32

VBUS34

VBUS33VBUS20

VBUS19

VBUS38

VBUS10

VBUS29

VBUS4

VBUS3

VBUS27

VBUS36

VBUS23

VBUS35

VBUS22

VBUS18

Slack Bus

E_1_2_1T

E_2_3_1T

E_3_4_1T

E_4_5_1T

E_6_7_1T

E_7_8_1T

E_8_9_1T

E_9_39_1T

E_1_39_1T

E_2_25_1T

E_25_26_1T

E_26_27_1T

E_26_28_1T

E_28_29_1T

E_26_29_1T

E_17_27_1T

E_16_17_1T

E_15_16_1T

E_16_19_1T

E_16_21_1T

E_16_24_1T

E_14_15_1T

E_4_14_1T

E_17_18_1T

E_3_18_1T

E_6_11_1T

E_13_14_1T

E_21_22_1T

E_22_23_1T

E_23_24_1T

E_5_8_1T

P =

74

3.8

Q =

11

4.2

V =

1.0

29

VA

P =

52

9.7

Q =

23

5.7

V =

0.9

96

1

VA

P =

69

7.9

Q =

22

6.8

V =

0.9

91

8

VA

P =

53

5.2

Q =

16

4.5

V =

1.0

18

VA

P =

66

2.4

Q =

13

3.8

V =

1.0

07

VA

P =

57

3.7

Q =

10

1.5

V =

0.0

68

19

VA

P =

55

1.2

Q =

22

.96

V =

1.0

4

VA

P =

25

3.9

Q =

16

3.6

V =

1.0

52

VA

P = 975.2Q = 54.56V = 1.026

V

A

P =

68

1.8

Q =

23

5.6

V =

1.0

59

VA

P,Q

Lo

ad

10

0.0

E2

5.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,QLoad

100.0E25.0

P,QLoad

100.0E 25.0

P,QLoad

100.0E25.0

P,QLoad

100.0E25.0 P,Q

Load100.0

E25.0

P,QLoad

100.0E25.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,QLoad

100.0E25.0

P,QLoad

100.0E25.0

P,QLoad

100.0E25.0

P,Q

Lo

ad

10

0.0

E2

5.0

P,QLoad

100.0E25.0

T

-Lin

e

Lin

e1

E

T

-Lin

e

Lin

e1

E

T

-Lin

e

Lin

e1

E

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

230.0230.0

E

:1

23

0.0

23

0.0

E :1

23

0.0

23

0.0

E :1

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.

.

57 / 72

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.

58 / 72

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

59 / 72

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)

B_456_ B_822_T1

T

A detailed frequency dependant TLine

From bus 456 to bus 822, Circuit T1

~E

Source1

Syncronous machine

at bus 159

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.

60 / 72

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

61 / 72

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.

62 / 72

PSS/E Load Flow output

BUS 15 LBUS15 345 AREA CKT MW MVAR MVA %I 1.0154PU -7.75 DEG1 350.31KV

TO 16 LBUS16 345 1 1 -314.7 -151.7 349.3

LBUS15

N15E_15_16_1

TZ(f)

0.0 -

2000 [Hz]

V15_Ang

P = -314.7Q = -151.7V = 1.015

V

A

P1 : ...

V15 Angle

-7.74857

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.

63 / 72

Angle(deg)

Pout(MW)

Qout(MVAR)

4.1825

632.0

109.911

Initial Conditions from Loadflow

E

Volts(pu)0.9972

/ 1.0

/ 1.0

TE

Ef

Ef0

If

E

TM0TM

1 VmVT

Wpu

G1 + sT

G1 + sT

G1 + sT

E

Te

3

AV

Tm

Tm0

Ef0

Tmw

Ef If

E

GENROU

E

Enab

VTIT

3

IFEF

EF0

Vref

VSIEEET1

VCT

VREF

EnabExc

Exciter VREF

is loadflow terminal voltage...

VREF

0.0VS

E

TM0

Enab

W

Wref

TM

IEEEG1EnabGov

WRef1.0

Figure 8 Detailed synchronous machine model automatically generated by E-TRAN with

parameters taken from the PSS/E *.dyr and *.raw files

64 / 72

LBUS01

N1E_1_2_1

TLBUS02

N2E_2_3_1

TLBUS03

N3E_3_4_1

TLBUS04

N4

P,QLoad

322.0E2.4

P,QLoad

500.0E184.0

E_3_18_1

TLBUS18

N18 P,QLoad

158.0E30.0

E_2_25_1

TLBUS25

N25E_25_26_1

TLBUS26

N26

P,QLoad

224.0E47.2

P,QLoad

139.0E17.0

22.0345.0

E

:1

GBUS37

N37

VN37~

E540.0

0.445E_37_0_1

22.0345.0

E

:1

GBUS30

N30

VN30~

E250.0

146.154E_30_0_1

E_1_39_1

TGBUS39

N39

VN39

E_9_39_1

TLBUS09

N9E_8_9_1

TLBUS08

N8

P,QLoad

1104.0E250.0

~E1000.0

88.281E_39_0_1

P,QLoad

522.0E176.0

P = 522Q = 176

V

A

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. Users Manual February 2003

Prepared by:

Juan Carlos Garcia

Dharshana Muthumuni

Pei Wang

65 / 72

PSCAD ADVANCE TRAINING

Tutorial on Creating Custom Components


Date: August 2005

Revision: 2

Date: Feb 16, 2007

66 / 72

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.

CBKAK 21

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.

B

C

AAdder

67 / 72


Integrator

Purpose:

Calling external subroutines.

Storing data for computations in following (future) time steps.

The block should perform the following function

xdty x input y output

To keep things simple, use rectangular integration.

ttxttyty )()()(

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.

x y

Integrator

68 / 72


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.

ib

ia

Rbo

oRa

ib

ia

dt

d

LbMab

MabLa

vb

va

Use the transformers section to enter the L and R values. Connect the model to a source and verify the model.

Two coupled

wires with capacitance

a1

b1

a2

b2

Use the Branch section to add stray capacitance between the wires on the input side.

69 / 72


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.

wkEb _

speedw

kfifek /15.188

150_

if Field current kf Input parameter (constant) The inductances and resistances are the other inputs.

f1

a1

a2

w

f2

Simple

DC Machine

70 / 72

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

71 / 72

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

!

72 / 72

That concludes the Introduction to PSCAD and Applications course. Thank

you for your attention and participation. As you work with PSCAD in the

future, please remember we are available to provide assistance with any

simulation or modeling difficulties you may encounter. Please do not

hesitate to contact us at:

[email protected]

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:

[email protected]

Manitoba HVDC Research Centre Inc.

244 Cree Crescent

Winnipeg, Manitoba, Canada R3J 3W1

T 204 989 1240 F 204 989 1277 [email protected] www.hvdc.ca

F A X

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