8/12/2019 6.Chapter03

1/22

8/12/2019 6.Chapter03

2/22

The general steps that would %e re/uired to create a new power system model,

perform a simulation, analy0e results and %riefly description of each module is shown

as following1

- ile Manager1 This module allows the user organi0e many pro2ects and cases

which ultimately will %e created into the data%ase

- Draft1 This module allows the user to graphically s#etch power system circuit

to %e simulated nd all parameters associated with the particular component are

entered into the special menu associated with the component3s icon

- T-line4Ca%le1 Two special modules ha"e %een written to handle the comple$

computations which is re/uired to generate data for the o"erhead transmission line

modules and ca%le modules

- 5un Time1 This module allows the user to monitor and interact with the power

system simulation %y two way, one is the EMTDC simulation that runs until

simulation finish time is reached and the other one is real time digital simulator

( 5TD') 'imulation runs until the operator decides to stop it 6raphical icons of

meters, sliders and also the simulation %y initiating a fault se/uence through a push

%uttons are used on interface The run time co"er the operation of EMTDC with on

line graphical output displays under run time &hen the data input file and the

D'D78 and D'9:T su%routines ha"e %een assem%led automatically %y Draft or

manually %y the user, 5un time will compile and lin# D'D78 and D'9:T

su%routines to EMTDC, run, display output, allow for '8P';9T files to %e written,

ena%le restarts from '8P'9T files and pro"ides for on line ad2ustment for

parameters during the run with graphical icons of potentiometers, push %uttons and

switches - Multi Plot1 This module is used to plot and directly analy0e (%y ourier

analysis, rms "alues, harmonic distortion etc) the data generated %y the EMTDC

simulation and allows multiple graphs to %e com%ined and displayed on a common

page +.

3.1.1 Typi!al Stdies "sing PSCAD/EMTDC

EMTDC is software %ased electromagnetic transient simulation tool which can

%e accessed through P'CD The user is a%le to assem%le "irtually and concei"e

power system %y using %uilding %loc#s a"aila%le from supplied li%raries, or from user

*

8/12/2019 6.Chapter03

3/22

generated components 9ne of EMTDC3s strengths lines is its a%ility to model

comple$ power systems which may include ;=DC transmission schemes and their

associated controls with relati"e ease The simulation of studies routinely conducted

using EMTDC include *->.1

+ 6eneral power system electromagnetic transient studies

DC transmission configuration and controls

* Effect of CT' de"ises

> 'ynchronous and induction machine torsion effects and self e$citation

? 'tatic compensators

@ 8on-linear control systems

.1

5esistors (5), inductors () and capacitors (C)

Mutually coupled windings such as transformer

Distri%uted fre/uency dependent transmission lines and ca%les

Current and "oltage sources

'witches and %rea#ers

Diodes, thyristors and 6T93s

*A

8/12/2019 6.Chapter03

4/22

nalogue and digital control functions

C machines, e$citers, go"ernors, sta%ili0ers and inertial models

Meters and measuring functions

6eneric DC and C controls

;=DC, '=C, and other CT' de"ices

The power of EMTDC is tremendously increased %y its state of the art P'CD

graphical user interface P'CD allows the user to assem%le the circuit, run the

simulation, analy0e the results, and manage the data in a completely integrated

graphical en"ironment Together, P'CD4EMTDC is a "ery efficient tool for

electromagnetic transient simulation of power systems

3.# E&ipments Modeling in PSCAD/EMTDC Program

3.#.1 Transmission 'ine Modeling

There are three %asic transmission line modeling techni/ues in EMTDC1 P!

sections, the ergeron Model, and re/uency-Dependent ine Models The

re/uirements of the study will determine which of the three models is suita%le

simple Pi section model will gi"e the correct fundamental impedance, %ut

cannot accurately represent other fre/uencies unless many sections are used (which is

inefficient) !t also cannot accurately represent the fre/uency dependent parameters of

a line (such as s#in effect) !t is suita%le for "ery short lines where the tra"eling wa"e

models cannot %e used

The ergeron model represents the and C elements of a Pi section in a

distri%uted manner (not using lumped parameters li#e Pi sections) !t is roughly

e/ui"alent to use an infinite num%er of Pi sections e$cept that the resistance is lumped

(+4 in the middle of the line, F at each end) i#e Pi sections, it also accurately

represents the fundamental fre/uency !t also represents impedances at other

fre/uencies, e$cept that the losses do not change This model is suita%le for studies

where the fundamental fre/uency load-flow is most important (ie relay studies)

The re/uency-Dependent ine Model represents the fre/uency dependence of

all parameters This model ta#es longer to run than the ergeron model, %ut is

necessary for studies re/uiring a "ery detailed representation of the line o"er a wide

*B

8/12/2019 6.Chapter03

5/22

fre/uency range re/uency dependent models can %e sol"ed using modal techni/ues

or using the more ad"anced phase domain techni/ues

The most accurate of these is the fre/uency dependent model, which represents

all fre/uency dependent effects of a transmission line, and should %e used whene"er

in dou%t &hen using ergeron model, impedance4admittance data can also %e

entered directly to define the transmission corridor, for fre/uency dependent models

detailed conductor information (ie line geometry, conductor radius) must %e gi"en

This thesis ha"e %een chosen the fre/uency dependent model for the modeling

of ? #= transmission system 8am Theun 5oi Et , the description of this

model shown in chapter section > ->.

3.#.1.1 The (re&en!y Dependent 'ine Model

The re/uency Dependent ine Model is %ased on the theory de"eloped in

B. !n order to arri"e at the time domain formation of the line e/uations, it is

con"enient to first wor# in the fre/uency domain, where an e$act solution for a gi"en

fre/uency is possi%le

Consider the following circuit of a transmission line as seen from the

terminations1 as show in igure *

igure * The tra"eling wa"e fre/uency dependent line model .

or a gi"en fre/uency, the "oltage and currents at one end of the line may %e

represented in terms of the "oltage and current at other end %y 1

( ) cosh ( ) . ( ) ( )sinh ( ) . ( )k m c mV L V Z L i = , (*+)

sinh ( ) .( ) ( ) cosh ( ) . ( )( )

k m m

c

Li V L iZ

= , (*)

>

8/12/2019 6.Chapter03

6/22

where1

( ) ( ) ( )Y Z = 1 Propagation constant

( ) ( ) 4 ( )cZ Z Y = 1 'urge impedance

( )Y G j C = + 1 'hunt admittance of the line

( )Z R j L = + 1 'eries impedance of the line

6 1 'hunt conductance of the line

C 1 Capacitance of the line

y introducing the forward and %ac# ward tra"eling wa"e functions kF and kB

in the node kfrom igure **

( ) ( ) ( ) ( )k k C k F V Z i = + , (**)

( ) ( ) ( ) ( )k k C k B V Z i = , (*>)

and similarly at node m

( ) ( ) ( ) ( )m m c mF V Z i = + , (*?)

( ) ( ) ( ) ( )k m c mB V Z i = (*@)

'u%stituting e/uation (*>) into e/uation (**) gi"es1

( )( ) ( )k k kF V B = , (*+

8/12/2019 6.Chapter03

7/22

igure ** re/uency Dependent e/ui"alent line model .

E/uation ( *B ) and ( *+ ) relate the source ( )kB with the m side /uantities

( )mV and ( )mB

!ntroducing in node k

( ) ( ) ( ) ( ).k m mB A V B = , ( *+ )

nd similarly in node m

( ) ( ) ( ) ( ).m k kB A V B = , ( *+* )

E/uation ( *++ ) and ( * +* ) are represented in igure ** in the time domain

The pro%lem howe"er, is the multiplication in e/uation ( *+* ) multiplication of

fre/uency domain %ecomes con"olution in the time domain

( ) ( ) ( ) ( )

t

m mA B A u B t u du

( *+> )

The e/uation (*+>) is tra"eling time (t) %ecause an impulse on one end of line

will not reach the other end until G second The tra"eling time is calculated using the

imaginary term of the propagation constant This e/uation is still in a "ery

incon"enient form for a time domain solution %ecause with each time step, more and

more terms of the con"olution integral must %e e"aluated ortunately, the

con"olution can %e computed in a recursi"e form suita%le for time domain solution

&ith the reference to the P'CD4EMTDC line model, the selected transmission

line models are transposed fre/uency dependent phase model %ased on tra"eling time

and characteristic impedance of the line The ? #= dou%le circuit lines %etween

8am Theun (8T8) to 5oi Et (5E) su%stations with *>? #m length of the line

is di"ided into two parts The +*? #m line from 8T8 '=H with

8/12/2019 6.Chapter03

8/22

MCM C'5 of conductor is di"ided into +* sections !t is illustrated in ppendi$ ,

igure - *

The input data re/uired %y each section for e$ampleI section length, phase

transformation data, tower configuration and ground conducti"ity are shown in ta%le1

*+

Ta%le1 *+Data input for transmission line model

Tower configuration

- 5elati"e J position of tower center on right of way

- 'hunt conductance

- 8um%er of conductors

- 'how graphic of conductor sag

- !s this circuit ideal transpose

- ;ow many ground wires

- Estimate ground wires

'ym%ol

( m )

( s4m)

( 7es48o)

( 7es48o)

( 7es48o)

( 7es48o)

Conductors data

- Conductor radius

- Conductor DC resistance

- 'ag of all conductor

- 8um%er of su%-conductors in a %undle

- undle configuration ( 'ymmetrical or non symmetrical )

- 'how %undle graphics

- ;ori0ontal coordinate and height distance

- Phase48ode connection information

( m )

( 4#m)

( m)

( 7es48o)

( 7es48o)

( J47)

6round wires data

- 8um%er of ground wires

- 6round wires radius- 6round wires DC resistance

- 'ag of all ground wires

- ;ori0ontal coordinate and height distance

(m)( 4#m)

( m )

( J47)

9ther data

- ength of line

-Tline interface componentand Tline info Component

- 'teady state fre/uency

- 6round resisti"ity

(#m)

(;0)

()

>*

8/12/2019 6.Chapter03

9/22

The data preparation and input data in the selected transmission model can %e

e$plained or the ? #= dou%le circuits from 8am Theun su%station to

'a"anna#het 2unction (8T8 '=H), the representation is shown in igure *? with

the following step

- 'elect the Tline !nterface Component and Tline!nfo Component from

Master i%rary

- 8ame the circuit as 8T8-'=H for %oth Tline !nterface Component and

Tline!nfo Component

- ssign the line parameter for Tline!nfo Component and tower

configuration according to the e$isting of ? #= transmission line 8am

Theun 'a"anna#het 2unction (8T8 5E )

Tline !nterface Component at the sending end and the recei"ing end of the ? #=transmission line 8am Theun 'a"anna#het 2unction

>>

8/12/2019 6.Chapter03

10/22

8/12/2019 6.Chapter03

11/22

Edit parameter for Tline !nfo '=H-5E

igure *?Tline !nterface and Tline !nfo Component for 'a"anna#het Hunction 5oi

Et model

3.#.# Transformer modeling

The thesis there is two selected transformer models The single phase

model is used for single phase step up power transformer at 8am Theun su%station

and step up power from generator +A #= connecting with single phase step up power

transformer +A4 ?? #= The three phases model is used for three phases step down

power autotransformer at 5oi Et su%station and step down power from line ?? #=

- > #=- #= "ia the 5oi Et su%station

Transformer models as shown in igure *@ are represented in detail with the

following information re/uired for the P'CD4 EMTDC transformer components1

- Transformer M= rating

- &inding configuration and winding "oltage

- Transformer tap change range and normal setting

>@

8/12/2019 6.Chapter03

12/22

- ea#age reactance %etween windings (this information can %e o%tained from

the load flow data used in system operating studies, if not readily a"aila%le

from the name plate data )

- Knee point of transformer core saturation characteristic in per unit of rate flu$

or "oltage

- Estimated saturated air core reactance of transformer and winding it is %ased

on

- ased operation fre/uency

igure *@ 'ingle and three phases transformer model in P'CD4EMTDC

3.#.3 )enerator modeling

The generator can %e represented %y the infinite source series with

su%transient impedance matri$ The su%transient matri$ can %e %uilt %y the same

procedure as the three phases transformer as following1

- Positi"e se/uence impedance (J+)

- 8egati"e se/uence impedance (J)

- Lero se/uence impedance (Jo)

- ase M= (three phases)

- ase "oltage (- rms)

- 'ource impedance type

>

8/12/2019 6.Chapter03

13/22

8/12/2019 6.Chapter03

14/22

'urge arrester is characteri0ed with a nonlinear "oltage "ersus resistance

characteristic The model will %e presented %y entering points on the =-!

characteristic, or the default characteristic may %e applied !t is suita%le for designing

switching surge, temporary o"er"oltage protection as shown in igure *A

igure *A 'urge arrester model in P'CD4EMTDC

3.#., Cir!it -reaer Modeling

The circuit %rea#ers are modeled as simple time controlled switches in the

P'CD4EMTDC program as shown in igure *B The program allows "arious

options to "ary the closing time ranging from one-shot deterministic closings to

>B

8/12/2019 6.Chapter03

15/22

multiple shot statistical closings or the statistical switching simulations, the

characteristics of the mechanical operating parts are modeled %y a random pole

spreading with a standard de"iation for the three phase %rea#er operating times

5andomly generated switch closing times "arying are also used to account for random

operation at any point on the power fre/uency wa"eform

The component allows simulation of single phase circuit %rea#er operation The

9penN and CloseN resistance of the %rea#er is specified along with its initial state !f

the input is , the %rea#er will close !f the input +, the %rea#er will open The %rea#er

current may %e la%eled and monitored "ia an output channel if desired pre-insertion

and post-insertion resistor may %e represented if re/uired The data input for circuit

%rea#er model is shown in ta%le1 *

Ta%le1 * Parameter input for circuit %rea#er model

Configuration

- rea#er name ( the name should %e the same as the output signal

la%el of the %rea#er logic component

- 9pen possi%le if current flowing

- :se pr-insertion resistance

'ym%ol

( 7es48o)

( 7es48o)

rea#er main data

- rea#er close resistance

- rea#er open resistance (Enter large "alue than close resistance)

()

()

Pre-!nsertion data

- Pre-insertion resistance 1

- Time delay for closing %rea#er

- Time delay for %ypassing pre-insertion

(sec)

(sec)

?

8/12/2019 6.Chapter03

16/22

igure *BCircuit %rea#er models in P'CD4EMTDC

3.#. Shnt 0ea!tor Modeling

'hunt 5eactors in the studied ? #= system are modeled %y simple

lumped element The locations of shunt reactors are identified The neutral reactors

are installed in the neutral of the shunt reactors as presented in igure *+

igure *+Configuration of line connected shunt reactors with a neutral reactor

The shunt reactance "alue of **?? M"ar line shunt reactor at 8am Theun side

per circuit and *?? M"ar line shunt at 5oi Et side per circuit can %e calculated

from the rate capacity with %ased "oltage ?? #= as following e/uation *+B1

or shunt reactor rate of M"ar

5eactance

( .)

( r)

Voltage kVX

Base Mva= (*+B)

3.#. 'oad Modeling

?+

8/12/2019 6.Chapter03

17/22

The e$ternal grid connecting with autotransformer ??4>4 #= at 5oi

Et su%station are considered in load model The e$ternal e/ui"alence networ# is

employed to reduced the rest of the 5oi Et su%station ?4* #= The complete

e$ternal networ# will %e reduced to a "oltage source %ehind a The"enin e/ui"alent

matri$ of Le/ The Le/is o%tained %y initiali0ing a three phases fault at the respecti"e

%us and o%taining the se/uence impedances at the faulted %us The e/ui"alent source

from ppendi$ B is used for this study The magnitude and phase angles of all

"oltage sources are found from a load flow program

3.3 Initial Condition of Program

There are generally two ways to start a simulation1 start from time t O with

no initial conditions or start with pre-calculated initial conditions imposed on some or

all elements !n this study, starting a simulation with initial conditions is achie"ed %y

using a 'napshot ile This can %e accomplished in program %y ta#ing a snapshot at a

time 2ust pre"ious to the switch opening 'u%se/uent runs could %e started from this

snapshot file, which would ha"e stored, among other "alues, the current flowing in the

inductor at the time of the snapshot ll studied cases start at steady state condition %y

the used of snapshot feature

3.+ The A!!ra!y of the Models

To analysis of the studied system with the simulation, the models must %e

"erified ll these sophistications in the simulation techni/ues increase considera%ly

the comple$ity and potential "alue of the studies, %ut this of little practical use

without accurate inputN data related to the transient %eha"ior of actual system

elements Therefore, the caution of the model is "ery important and in this thesis, the

accuracy of the model is chec#ed for "alidity with the following cases1- Comparison with T8 case study for line energi0ing of the Mae Moh to Tha

Ta Ko circuit + @., A.

2 Comparison with line energi0ation o"er"oltage study report of E6T on the

? #= transmission line 8am Theun to 5oi Et pro2ect .

3.+.1 Comparison with TA !ase stdy for line energi4ing of the Mae Moh

to Tha Ta 5o !ir!it 1

The switching o"er"oltage of ? #= Mae Moh (MM *) to Tha Ta Ko

(TTK) circuit + in case of line energi0ation was ta#en from T8 case study to

?

8/12/2019 6.Chapter03

18/22

compare with the result The purpose is to chec# the accuracy of the selected models

and the reference case (MM* TTK) is /uite similar to the studied system (8T8

5E) @-A. The networ# of MM* TTK circuit + is shown in igure *++

igure *++ 'ingle line diagram Mae Moh ThaTaKo circuit +

ll e/uipments are represented in ? #= transmission line Mae Moh * to

ThaTaKo circuit + with the following detail1

- 6enerator model is the %asic The"enin "oltage sources, three phases $ matri$

and short circuit impedance

- Transformers modeled1 or each transformer is represented in detail with thise$iting information1 M= rating &inding configuration and "oltage, tap

change ranges and normal setting, lea#age reactance %etween windings Knee

point of transformer core saturation is characteristic in per unit of rate flu$ or

"oltage, and estimated saturated air core reactance

- Transmission line model1 The selected transmission line models are distri%uted

parameter models %ased on the tra"eling time and characteristic impedance of

the line The section of ? #= line Mae Moh ThaTaKo are presented %y

untransposed fre/uency dependent line model

- Circuit %rea#er model1 the locations of the circuit %rea#ers that will %e

switched are identified on the studied system 9ther parameters of the circuit

%rea#er are determined

- rresters models1 the installed location and rating of surge arresters are

pro"ided The ma$imum ratings and particular the energy a%sorption

capa%ility is determined with these studies

?*

8/12/2019 6.Chapter03

19/22

- 'hunt reactors models1 the location of shunt reactors is identified This is

included whether They are line connected or %us connected

3.+.# 0eslts of the Stdies

The studied line energi0ation case ? #= transmission line Mae Moh to

Tha Ta Ko circuit + is shown in igure *++

Phase

igure *+ MM *-TTK circuit + wa"eform from P'CD4EMTDC () and T8 ()

The T8 result and P'CD4EMTDC result show relati"ely the similar

wa"eform with the same condition for %rea#er operation as shown in igure *+

3.+.3 Comparison with line energi4ation o6er6oltage stdy report of E)AT

on the ,77 8 transmission line am Then # to 0oi Et # pro9e!t

The EMTP study is conducted to in"estigate the switching o"er"oltage

occurring during switching of the line circuit %rea#er on each side of the ? #=transmission line %etween 8am theun pro2ect and E6T3s networ# at 5oi Et

Phase

Phase C

( ) ()

1.,7 p.

?>

8/12/2019 6.Chapter03

20/22

su%station The initial study is for E6T planning de"elopment %efore the pro2ect

starting . The Dig'!E8T software program was used for the study fter

confirmation of the selected model from the pre"ious section, the studied system is

represented with the e$isting parameter and information related to E6T studied

case The simulation is performed in three steps as follows1

Step 1 1 Prior to the switching action commencing , E6T3s system is in a

normal steady state operating condition ll circuit %rea#ers at %oth ends of

these two circuits are opened and all generators at 8am Theun Power Plant are

off line

Step # : ll generators of 8am Theun Power Plant are running at no load

synchronous speed while all line circuit %rea#ers at %oth ends of two circuits are

still open

Step 3 1 9ne set of line circuit %rea#ers on one circuit of the dou%le circuit lines

at 8am Theun end is closed

Ta%le1 ** 'imulation results from Dig'!E8T and P'CD4EMTDC program

Detail Dig'!E8T simulationof E6T

P'CD4EMTDCsimulation

Energi0ed from 8am Theun Power Plant

Ma$imum 9"er"oltage ( #=) -A+

8/12/2019 6.Chapter03

21/22

igure *+* The "oltage wa"eform of P'CD4EMTDC simulation

igure *+> The "oltage wa"eform of Dig '!E8T simulation

3., Con!lsion for the A!!ra!y of the Models

The accuracy of the P'CD4EMTDC modeling program of the system

components as well as lines, transformers, generators, circuit %rea#ers, shunt reactors,

surge arresters, loads are presented %y ta#ing into account the saturation of

transformer, shunt reactor and surge arresters The raw data has to %e con"erted to the

suita%le "alue %efore input to the program

The accuracy of the model with T8 case Mae Moh to Tha Ta Ko, the results

from simulation are similar This comparison is ta#ing the selected e/uipments model

and methodology of the studied for impro"ement of the selected model in case of

8am Theun to 5oi Et

The accuracy of the model with comparison of line energi0ation o"er"oltage

EMTP study report of E6T on the ? #= transmission line 8am Theun to 5oi Et

pro2ect, the simulation from P'CD4EMTDC and Dig'!E8T program are in good

agreement

!n case of the model "erification, it can %e concluded that the analysis of

transient o"er"oltage used P'CD4EMTDC program in case Mae Moh to Tha Ta Kothe ma$imum o"er"oltage are the same "alues and comparison with line energi0ation

?@

8/12/2019 6.Chapter03

22/22

study report of E6T on 8am Theun to 5oi Et The ma$imum o"er"oltages from

%oth are similarly The simulation had the identical system configuration as the

reference case The "oltage wa"eforms are almost identical, the comparisons gi"e

satisfactory results, further confirming the accuracy of the simulation model and used

parameters Therefore, the selected models in this thesis are accuracy and can %e used

for analysis of the proposed system

?