Tutorial_PSCAD

PSCAD : POWER SYSTEM

SIMULATOR

Copyright 2005

1

WELCOME TO THE PSCAD

INTRODUCTORY TRAINING COURSE

I General Features

II First steps with PSCAD III Introduction on control systems IV Breakers & Faults

SUMMARY

2

V Switching & Interpolation VI Transformers in PSCAD VII Rotating Machines in PSCAD VIII Transmission Lines & PSCAD IX User Component

X Organizing the Worksheet XI Matlab Interface

I General Features

I General Features

PSCAD: General Features

Load Flow / Transient Stability

z Each solution based on phasor calculations z Sequential time domain

calculations

Electro-Magnetic Transients = PSCAD z Direct time domain solution of

Differential Equations z Trapezoidal integration 4 calculations R L II V

( )

[

]

Selection of

Simulation Tools

Stability/Load Flow Tools

(Phasor Solutions) z Valid only for Steady State

and Low Frequency Swings

Transients Tools (PSCAD)

(Time Solutions) z Valid Over a Wide

Frequency Range z Detailed Analog and Digital

5 z Simplified Controls

(approximated as S functions)

z Steady State Equations for HVDC

z Efficient for Large Systems

z Detailed Analog and Digital Controls

z Detailed Switching of Thyristors, Diodes, GTO’s z Harmonics

z Transient Overvoltages, Lightning Impulses z Machine Dynamics

Transient vs Steady State

z Transient solution

‹Harmonics ‹Non-linearities ‹Frequency dependent

effects

z Steady state solution

Typical studies

z Find the over voltages in a power system due to a fault or a breaker operation

z Over voltages due to lightening strikes

z Find the harmonics generated by Power electronic devices (SVC,HVDC link, STATCOM, Machine drives)

7 z Tune and design control systems for maximum performance z Investigate sub synchronous resonance (SSR)

z Study the interaction between the SVC,HVDC links and other non linear devices.

z Variable speed drives z Industrial systems

Typical studies- Power Quality

• Grounding methods

• Over-voltages due to switching

• Voltage sags

• Iron saturation – inrush

• Performance of FACTS devices

8

• Ferro resonance

• Active and passive filters

• Distributed generation

• Flicker

• Variable speed drives and related harmonics

• Industrial systems

PSCAD: Simulation Theory

Based on Dommel’s representation of power system components

Admittance matrix based

[i] = [Y] [v]

PSCAD: Simulation Theory

Example: How an inductance is modelled ?

10

Integration of components

to form the system

z Compiles the circuit draft to form the FORTRAN file z Defines the Y matrix (map file)

z Subroutines are called to compute R and I of models at a given time step

11 z EMTDC :

♦Solves for node voltage based on Y and I values ♦Increments the time step

z FILES :

♦PSCAD shematics: *.psc file

♦directory *.emt : contains data file, map file, line.* files, output files

PSCAD: Specifications

PSCAD needs a Fortran Compiler to run:

z Compaq Visual Fortran V5 or V6 (Intel Fortran Compiler v9)

Th f GNU F77 il i d li d ith PSCAD

z The free GNU F77 compiler is delivered with PSCAD: Limitations

PSCAD: Limits

FORTRAN F77 Compaq Visual FORTRAN ( V5 ou V6)

Electrical Nodes 200 Unlimited Electrical branches 2000 Unlimited Sub-pages 25 Unlimited

13 Sub pages 25 Unlimited

T-Lines/Cables 50 Unlimited Transformers 70 Unlimited Educational edition Electrical Nodes 200 Electrical branches 2000 Sub-pages 25

II First steps with PSCAD

14

II First steps with PSCAD

Menu « Edit - Workspace

Settings »

z Fortran:

Select your FORTRAN compiler

z Matlab:

Choose your MATLAB version

16 and the corresponding libraries

z License:

Licensing info and installation

z Preferences:….

PSCAD: Step by step

1) Create or load a project

2) Select the components from the library

3) Define the components and connect them with wires 4) If d d d i t l d i

17 4) If needed, prepare dynamic control devices

5) Prepare plotting and metering tools 6) Parameterize the simulation => time step,

parameters...

Create Projects

z To create a new case: [File][New][Case] or :

z To load an existing project: [File] [Load Project] or :

Activate Projects

zTo activate a project: Click on the project name then [Set as active]: The project name becomes blue

‹Only one project is active

Only an active project can be run and saved

19 ‹Only an active project can be run and saved

Access to the Master Library

zAll the PSCAD components are saved in the MASTER LIBRARY

20

Define components

On Line Help

z[Help][Table of Contents]

22

zOr directly click on the [Help] button from the dialog box of a component

On Line Help

Measurement

z In component parameters window, define a name to measure internal variables: (eg: Output voltage of 3 phase voltage source)

z «Multimeter » component to measure: v,i,P,Q,Vrms,theta…. anywhere in the model

Plotting Devices

Plotting Curves/Metering

Plotting Curves/Metering

Plotting Curves

28

Plotting Curves

29

Metering

•Steps 1 & 2are the same: Prepare the output Channel •Step 3 :Select the « Control Panel » component

Metering

Step 4:[Input/Output Reference] from the output channel

31 Then [Paste] on the control Panel

Plotting Curves/Metering

characteristics for the display of the measured value : (Title, Scale Factor, Unit,etc...

32

Project Settings Menu

zDuration of the Simulation

zSolver Time Step

How to export results ?

1) Copy results from one graph to Excel or text files

34

How to export results ?

zIn the project settings menu « Save Channels to disk »:

2) Save directly all the measured quantities in output files:

35

zOutput files (text files) will be created in the *.emt directory

zAssociated *.inf files can be directly opened in Livewire (offline PSCAD post processor)

Dynamic Control Devices

•Possibility to change dynamically (during the simulation) the values of parameters owing to several dynamic control devices:

•Slider: •Switch: •Push Button: •Dial:

Dynamic Control Devices

•Step 1 : Select your control devices

Operating Mode: example with a slider

37

Dynamic Control Devices

38

Dynamic Control Devices

Dynamic Control Devices

40 Then [Paste] on the control Panel

Snapshot

A Snapshotallows to launch a simulation having initial conditions given by a previous simulation

1) Run a first initialization simulation until to reach the steady

41 1) Run a first initialization simulation until to reach the steady

state and save results in a snapshot file

2) Launch transient simulations starting from snapshot files

Snapshot : Operating mode

2) Define the snapshot time & File and run the initialisation simulation

Multiple run Simulations

parameters

z To find the best parameter values or the « worst case » (fault study) z Insert the following component directly in your project:

43

Parameters of the project which are monitored in the multiple solution Measured values

which will be recorded in the multiple run output file *.out

Multiple run : Operating mode

Specify the parameters variation law of themonitored parameters

44 Type of variation: list,sequential or random Boolean, Real or Integer ? List of values

Multiple run : Operating mode

Specify the recordedquantities

N b f d d

Number of recorded

quantity Recorded quantity:integer, real or boolean ?

III Introduction on control

systems

46

systems

Variable parameters

zVariable parameters in PSCAD:

♦Control signals for Power electronic devices

♦Control signals for Breakers and Faults

♦Electrical quantities externally controlled

47 ( eg: Voltage Source Magnitude, RLC values,…)

z Possibilities to design control systems with:

♦mathematical function blocks

♦sequencers

♦user interactive control tools

Control Blocks

zControl system is defined by connecting:

♦Constants and Time inputs

♦Sinusoidal functions ♦Comparators ♦Transfer functions ♦Min, max… ♦Look up table ♦Filters

Control Blocks

zExample:

49

Sequencers

zState graph form:

50

Breaker model

Single phase breaker: 1 model - 2 display

Low voltage display High Voltage display

52 Three phase breaker: 1 model - 3 display

o o tage d sp ay g o tage d sp ay

Low voltage display High Voltage display (single line)

Breaker: Parameters

Name, Roff, Ron

53 Possibility to define pre and post insertion resistances

Single pole operation: possibility to operate each phase separately

Breakers Control

zPredefine the initial state and operation time in the « Timed Breaker Logic » component:

z Link the breaker with a user interactive control tool:

Fault model

Single phase fault:

55 Three phase fault:

Three phase view Single line view

= 2 state switching resistors RON,ROFF

Fault control

zDefine the fault duration ant the time to apply fault in the « Timed Fault Logic » component:

56

z Dynamic control tools

z Sequencers:

zControl blocks ( 0: fault removed ; 1 :fault applied)

Fault control

If the option «external»control is selected, the fault type can also be externally monitored:

V Switching & Interpolation

58

g

p

Semi-Conductors Models

Available Semi-conductors models in the PSCAD Master

Library : 59 Library :

Semi-Conductors Models

Diode characteristic

Parameters:

z Ron/Roff values F d V lt D V l

61

z Forward Voltage Drop Value

z Snubber Circuit Resistance & Capacitance

Note: The reverse recovery time of the diode is assumed zero

Thyristor characteristic

z Ron/Roff values

z Forward Voltage Drop Value z The Forward Break-Over Voltage: Device will be forced into conduction if this

62

voltage is exceeded (with or without a gate pulse) [kV] z The Reverse Withstand Voltage:

Device will be forced into conduction in the reverse direction if this voltage is exceeded [kV]

z The minimum extinction Time (min of δt between Roff and Ron) z Snubber Circuit Resistance & Capacitance

GTO/IGBT characteristic

z Same characteristics as for the thyristor TURN OFF i l t b it d

Power Electronic Switching

& Time step

zPSCAD has a fixed Time Step

64 zControl system need a small time step to switch at exact

instant :

=> « Interpolation method »

Interpolation Method

Current crosses zero

t1 y1 y 1−y2 dt y 1 t 1 := y 65 t- dt t y2

Current crossing time t1 can be estimated

Interpolation Method

4 – OFF (new G matrix) 5 – dt ahead from 4

Interpolation Method

Advantages of this method:

z Accuracy:Switching is made at the ‘exact’ instant F t C b t l ti t d i t i

67 z Fast:Can be run at a larger time step and maintain

accurate results

VI Transformers in PSCAD

68

PSCAD & Transformers

zTwo different models for power Voltage Transformer:

‹«Classical» models: single and 3phase ‹«UMEC» models: single and 3 phase

Available in the PSCAD Master Library:

Classical Models

Classical models:

zSingle phase: 2 or 3 windings

z3 phase: 2,3 or 4 windings, autotransformers

70

p , g ,

zNo mutual coupling between the 3 phases => equivalent to 3 single phase units

Representing transformers as coupled coils

z Mutual inductance: Flux linkage

z Self inductance: Leakage inductance & Magnetizing inductance

Classical Models

71

UMEC models

Unified Magnetic Equivalent Circuit:

zTake the geometry of the core into account (ly,lw,Ay,Aw)

zMutual coupling between the

Equivalent to classical models but the inductances are dependent of the core dimensions: Lij(ly,lw,Ay,Aw)

zMutual coupling between the different phases are considered

UMEC models

z Single Phase Models: 2,3 or 4 windings

73

z Three Phase models: 2 windings/phase with 3 or 5 limbs

Equivalent Circuit

74 L1,L2: Positive Sequence Leakage reactance

L12 : Magnetizing Inductance R1,R2: Copper Losses

Iron Losses : Shunt resistance with L12

Parameters

zVoltages levels at the primary and secondary side

( not only a ratio ! Important for p.u computations) zApparent Power (MVA)

Wi di t ( Y )

zWinding types ( Y or )

zPossibility to modify dynamically the turns ratio during simulation as a « Tap changer »

Parameters

z Positive sequence leakage reactance (pu): L1+L2 (from short-circuit test)

z Magnetizing Current (pu): % of rated current => L12 (from open-circuit test)

76

( p )

z No load losses (pu): Core losses

z Copper losses (pu): resistance of windings : R1+R2 All parameters of the equivalent circuit are defined in per unit

(i.e / Zbase) :

Zbase=V1*V2 / Sn

« Ideal Model »

User can select an « ideal » model or not for the transformer: 'Ideal' means that the

magnetizing branch has been eliminated in the equivalent circuit:

77 equivalent circuit:

1) Very small magnetizing current ( << 1%)

=> numerically more efficient and stable to neglect the magnetizing inductance in the equivalent circuit

Why choosing Ideal Model ?

2) To consider non linearities in the core, useful for:

‹Harmonic distorsion studies

Representing saturation

In PSCAD, saturation is represented with a compensating current source injection across the selected winding

The magnetizing branch is replaced by a non linear magnetizing current source

79

Flux linkage

Mag. Current

λ

Im1 Im2

User define parameters for the curve V (Is):

z Knee voltage (generally 1.15 to 1.25 pu)

z Slope: Air core reactance (generally 2*leakage reactance)

z Dynamic parameters (Time constants)

Saturation in Classical

approach

80

y a c pa a ete s( e co sta ts)

Introduction to Electric

Machines

• 2 models: Squirell Cage and Wound Rotor • DC Machine:2 winding models

• Synchronous Machine :2 models available: Wound rotor or Permanent

82

Synchronous Machine : 2 models available: Wound rotor or Permanent Magnet model

• Full model of exciters and power system stabilizers can be associated to synchronous machine

• Turbine and Governors ( Steam, Hydro, Wind) models can be connected to the machine :

• To compute precisely the mechanical effects • Multi-mass Model: to model Shaft Torsional effect

Electric Machine Simulation

Represented as a system of coupled coils

zeg: Salient pole synchronous machine – 6 coils

83 Inductance Matrix [L] with rotor position dependent inductances

Electric Machine Simulation

The solution is based on admittance matrix:

[i] = [Y] [v]

=> Requires that [L] be inverted at each time step => Slow and computational inefficiency

The inductance matrix is converted from the ‘a-b-c phase reference frame’ to d-q-0 frame: Park Transformation

zMathematical transformation

zSymmetrical windings and linearity assumed

Electric Machine Simulation

Machine data for simulation:

zObtained from tests or given by manufacturer

zIn a form suitable to be used in d-q based models:

‹“Generator data format”: Classical parameters :

85

‹ Generator data format : Classical parameters : Reactances and Time constants:

‹D axis: Xd,X’d,X’’d,T’d0,T’’d0

‹Qaxis: Xq,X’q,X’’q,T’q0,T’’q0

‹“Equivalent circuit data format”: Reactances and Resistancesfor d-axis and q-axis equivalent circuit

Shaft Torsional effect modelling

zInteraction of the electrical and mechanical systems

=> Multimass model connected to Synchronous generator

86 T12−Te J1 tw1 d d ⋅ +D1⋅w1+D12⋅

(

)

(

)

(

)

Synchronous machine

initialization process

• To quickly and smoothly reach the steady state at a desired working point, user can :

♦Start the machine in « normal mode » but user has to set the proper inital conditions: P0,Q0,Ef0,Tm0

♦Or use the initialization process implemented in PSCAD: 1) Start the machine as a voltage source:

VIII Transmission Lines & PSCAD

88

Transmission Lines

Selection of a suitable model:

zAvailable data: Geometric data or Parameters

zSpeed of simulation: Time step

Li l th F l t t h d d f K

89 zLine length: From several meters to hundred of Kms

zType of study: Fast transient, Low transient, RMS

zAccuracy

Representing

Transmission Lines

Equivalent circuit model:

Equivalent circuit model

R,L and mutual inductances between wires R,L

91 Lumped parameters model

Travel time became small (compared to time step) up to several Kms To use for very short lines

Travelling Waves model

Travelling wave models:

zPropagation delay between sending end and receiving end

zFrom several to hundred of Kms

zBergeron Model:Accurate at a single frequency

92 => for Rms or low transient studies (fault analysis)

zFrequency dependent models:

accounts for the changes in line parameters due to frequency -Phase model : Most accurate model available

- Mode model: Older model (available for PSCAD V2 compatibility)

Travelling wave models

User represents:

zThe geometry of the corridor

zSag, ground wires

zConductor resistivityCo ducto es st ty

Travelling wave models

Before the global simulation of the system, the parameters of the lines are computed : Line Constans Programs

zCompute equivalent Shunt admittance Y and Series impedance Z

zReduced to Nth order Transfer functions

Curve Fitting for the frequency spectrum chosen by user

94 For Bergeron model,

Manual entry is possible:

zCurve Fitting for the frequency spectrum chosen by user

IX User Component

95

p

EMTDC:

Simplified Solving Process

Master DYNamics Subroutine DSDYN Network Solution t0 OUTput Subroutine t1 =t0+δt Network Solution DSOUT

DSDYN: Solves control systemswhich will be used for the electrical network drive at the same time step

Network Solution: Solves electrical systems: [i] = [Y] [v]

EMTDC:

Simplified Solving Process

97 DSOUT: Same structure as DSDYN but specific use:

zSolves control systemswhich will be used for the electrical network drive at the following time step

zComputes quantities to be displayed in Meters & Graphs

Main advantages of EMTDC

structure

1) Possibility to solve cases even if there is no electrical circuits (only control blocks): only DSDYN& DSOUT subroutines are used

2) U d di tl i t d i DSDYN DSOUT ti

98 2) User code directly inserted in DSDYN or DSOUT sections:

possibility to use all the existing EMTDC subroutines in order to design custom components easier

3) With the judicious use of DSDYN or DSOUT, user can decide to calculate control dynamics using pre or post solution quantities and avoid unnecessary time step delays

Create a component:

General Steps

1) Create a library

2) Define the interface of the component 3) Parameterize your component 4) Define the Code

Create your own Library

First, you can preparate your own library:

100 Then save it, open the file and create your components

Create the component

The component wizard is opening:

101 Indicate:

zThe name of the component

zThe number of connections

Create the component

Indicate:

zThe connection name

zThe type of the connection: Electrical or C t l tit (i t Control quantity (input or output)

zThe type of the data: Logical, Real, Integer

Create the component

Confirm...

103 ... then you obtain something like this:

Parametrize your component

You access to a new window:

104 the « component workshop »,

then select the tab « parameters

Select « New Category »

Define « New control »

Parametrize your component

106 Then, choose the type of variable that the user will have the possibility to enter:

z Text

z Input Field (one value)

z Choice Box

Specify:

zThe elements to be displayed in the parameter

Parametrize your component

107 box (size, title, default

value…..)

zThe data type

Parametrize your component

If several parameters are created, it is possible to edit or modify each ones in selecting the corresponding name in the drop list

Define the Code

In the component workshopwindow, select the tab « Script »

The code is organized in different sections called «segment»:

109 Each segment has its proper syntax

(based on Fortran & PSCAD script)

Segments

z Fortran:Design code or call subroutines defined in external *.f files z Branch:To design electrical branches containing R,L or C

z Computations:for precomputations (compiled only at the first time step) z DSDYN:Fortran code forced in the DSDYN sections,

DSDOUTF t d f d i th DSDOUT ti

110 z DSDOUT:Fortran code forced in the DSDOUT sections

z Transformers:Syntax adapted to simply design mutual impedance matrix

z Checks:

z T-Lines: z etc….

The STORx arrays

The STORx arrays are storage vectors allowing to store variables at a precise location:

zSTORI,STORF,STORL,STORC for integer, real, logical or complex datap

zUseful if :

The STORx arrays

To use STORx arrays need to increment the corresponding NSTORx pointers:

zNSTORI, NSTORF, NSTORL, NSTORC

zExample:

Retrieve values from STORF:Xa = STORF(NSTORF)

112 Retrieve values from STORF: Xa STORF(NSTORF)

Save values in STORF : STORF(NSTORF) = Xb Increment the pointers:NSTORF = NSTORF + 1

X Organizing the Worksheet

113

g

g

Create sub_page

When the project becomes enough large, it is interesting to sudivide it into several pages organized in an arborescent structure: Main Page Main Page Subpage2 Subpage 1 Subpage 2_1 Subpage 2_2

Create sub_page

[Right Click] in the main page, the following menu appears:

115 Select « Create New

component »

Create sub_page

Indicate:

• the name of the sub-page

116 •The number of

connections between the sub_page and the main page

•Tick « Page Module

Create sub_page

Indicate:

•The connection name •The type of the connection: Electrical or Control quantity q y (input or output)

Create sub_page

Confirm and …….that ’s finished !!

118

Create sub_page

Links between pages : Electrical Nodes

The electrical connections between a sub_page and the

i li d ith th

119 main page are realized with the

following component called External Electrical Node :

Note : This electrical node must have the same name as the one declared during the sub_page creation

Create sub_page

the main page (declared as input during the connection d fi iti ) h t b i t d definition) has to be imported in the sub_page with the «IMPORT» component Notes:

XI MATLAB-Simulink interfacing

121

g

Matlab/Simulink Interfacing:

General features

•Cosimulation:Possibility to integrate Matlab files and all the functionnalities of Simulink toolboxes in a PSCAD project

•General organization:

122 •1) Call Matlab files (*.m) or Simulink files (*.mdl) from the PSCAD workshhet

•2) Need to define a user_component to interfacing PSCAD & Matlab/Simulink

•3) Both Matlab 5or 6 and a Digital Fortran 90 compiler should be installed on your PC

Matlab files Interfacing

Need to define a user_component to interface PSCAD & MATLAB :

Matlab files Interfacing:

Operating Mode

Step 1:Design the title & connections as any other user component with the PSCAD component Wizard

Step2 :Good Advice ! Parameterize the Name of the Matlab file and the corresponding path, then, the user component

124 p g p , , _ p will be more flexible & able to call other files

Matlab files Interfacing:

Operating Mode

1) Open the «DSDYN» segment

2) Allocate Memory : Exemple with a case with 2 real inputs A&B and 1 integer ouput C:

125 3)Transfer the input variable to STORF (real) / STORI (integer) arrays :

STORF(NSTORF) = $A STORF(NSTORF+1) = $B inputs A&B and 1 integer ouput C: #STORAGE REAL:2 INTEGER:1

Matlab files Interfacing:

Operating Mode

4) Call the Matlab Subroutine:

CALL MLAB_INT (« $Path », « $Name », « I R(31) », « R ») 5) Transfer Output variable from STORF/STORI arrays into the PSCAD output connection node:

the PSCAD output connection node: $C = STORI(NSTORI)

6) Increment the NSTORF & NSTORI index pointers: NSTORF = NSTORF + 2

Simulink files Interfacing

Need to define a user _component to interface PSCAD & SIMULINK :

127 Variable

defined in the PSCAD circuit

User_component: Send PSCAD data to a *.mdl file

Output of the *.mdl file, sent to the PSCAD project

Simulink files Interfacing:

Operating Mode

The same as for Matlab files excepted :

1) Call of the SIMULINK SUBROUTINE :

128 CALL SIMULINK_INT (« $Path », « $Name », « I R(31) », « R »)

2)You do not need to transfer Output variable from STORF/STORI arrays