Phần 10 KHÓA ĐÀO TẠO TÍNH TOÁN ỔN ĐỊNH VÀ ỨNG DỤNG TRÊN PHẦN MỀM PSSE CHO KỸ SƯ HỆ THỐNG ĐIỆN (Ngồn ngữ mô hình hóa hệ thống điện trên Phần mềm PSSE)

Ngồn ngữ mô hình hóa hệ thống điện trên Phần mềm PSSE.NỘI DUNG CHÍNH PHẦN 10 (Assembly of System Models): 1. Reduced Power System. 2. NonStandard Models using FORTRAN. 3. Introduction to Graphical Model Builder (GMB).

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TRANSMISSION &

DISTRIBUTION

A Division of Global Power

POWER SYSTEM STABILITY CALCULATION TRAINING

D 6 A bl f S t M d l Day 6 - Assembly of System Models

November 22, 2013 Prepared by: Mohamed El Chehaly

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2

OUTLINE

• Reduced Power System

• Non-Standard Models using FORTRAN Non Standard Models using FORTRAN

• Introduction to GMB

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3

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4 REDUCED POWER SYSTEM

Equivalents

 Equivalents represent a reduced network

that contains few original buses and all

boundary buses

 Study system: Buses subject to detailed

study; all components are represented

explicitly

 External system: Buses and branches that

connect to and influence a study system

but do not need to be represented

 Boundary buses: buses in the study

system that connect to external systems

through branches

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Steps for Equivalent Network

1 Swing buses in the study system

1 Verify that in the study system there is at least

one swing bus

2 If there is at least one swing bus, skip this step

3 If no swing buses assign a generator bus (code

3 If no swing buses, assign a generator bus (code

2) in the study system to be a new swing bus (code 3)

4 Solve the load flow No changes to the power

levels should be observed

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2 Swing buses in the external system

1 Change all the swing buses (code 3) in the

external system to generator buses (code 2)

2 Add loads on the boundary buses corresponding

to the power flows of the tie lines that connect the

to the power flows of the tie lines that connect the boundary buses to the external system (DO NOT SOLVE)

3 Disconnect the tie lines that connect the

boundary buses to the external system

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3 Removal of External Buses

1 After disconnecting the tie lines, solve the load

flflow

2 The load flow could not be solve due to the large

number of islanded buses

3 The following message should appear:

Message for API FDNS

#### buses in island(s) without a swing bus

Use activity TREE

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4 Islanded buses

1 Write TREE in the CLI window

2 The following message should appear:

3 To disconnect the island, write ‘1’ in the CLI

4 Repeat until all islands are disconnected

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5 Short-circuit levels

1 Determine the short-circuit levels (three-phase

and single-line-to-ground) at the boundary buses

and single line to ground) at the boundary buses

in the original system both in physical output (MVA and A) and in per unit (pu) and in polar coordinates

2 Add a dummy generator at the boundary bus of

the modified system with zero power and a y pcalculated impedance to match the original short-circuit level

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3 Verify that the error difference between the

original and the new short-circuit levels does not exceed 5%

4 In the original system, disconnect all lines with

the boundary buses except for the ties with the y pexternal system and calculate the short-circuit level in MVA

5 In the reduced system change the rating of the

5 In the reduced system, change the rating of the

equivalent generator to the value found in step 4

6 Change the impedances of the generator to the g p g

new machine base

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6 Power flows in the study system

1 Verify that the power flows within the study

system match the original power flows

2 If there is a large difference, add loads that

compensate this difference

3 Check that the power flows should be within 5%

of the original ones found in the complete system

4 Voltages and angles at all buses in the equivalent

system should match the ones in the complete system

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7 Completed equivalent network

1 The equivalent network is now completed

2 The buses of the external systems can be

deleted

3 Dynamic simulation can now be carried out on y

the equivalent system

4 The behaviour of the external systems in the

dynamic simulation is neglected

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Vietnamese Power System

 Vietnamese Map

Pl ik

External System Pleiku

Study System

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1 Swing buses in the study system

 No swing buses were found in the study system

 The only swing bus connected to it is HBINH_H1

(bus 28610) located in the North

 A new generator bus is chosen to be an

additional swing bus: PMY_1_S4 (bus 52040)

 Solve the load flow

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2 Swing buses in the external system

 Change all the other swing buses to generator

buses

 Add loads at the boundary bus corresponding to

the flows in the tie lines

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3 Removal of External Buses

 Solve and the following message appears

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4 Islanded buses

 Repeat for all islands

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 The short-circuit level at the boundary bus

PLEIKU (bus 3300) in the original system is:

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 The short-circuit level at the boundary bus

PLEIKU (bus 3300) in the reduced system is:

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 In order to get the impedance of the equivalent

machine the following equations have to be

machine, the following equations have to be solved for all sequence impedances

1 1

X

pu X

04389 0

02525

0

02518

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 In order to get the impedance of the equivalent

machine the following equations have to be

machine, the following equations have to be solved for all sequence impedances

1 1

X

pu X

04389 0

02525

0

02518

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 In the original system, disconnect all ties

including transformers on the boundary bus

including transformers on the boundary bus Pleiku 500 kV except tie lines connected to the external system and find the new short-circuit

le el

 The chosen value for the equivalent machine

base is 4000 MVA This will represent the contribution of the external system

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 The new values of the machine impedances with

the new machine base (4000 MVA) are the

the new machine base (4000 MVA) are the following:

pu

X1  1 0072

B 4000 MVA

pu X

7556

1

0100

1

0 2 1



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 The load flow at Pleiku is shown below for both

cases

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 The load flow at Phu My is shown below for both

cases

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equipment to be modeled or given a block

diagram and/or the differential and

algebraic equations

 Sufficient calculus and block diagram

equation to the form required of a PSS®E

model

 Familiar with the PSS®E data arrays (CON,

ICON, VAR, STATE…)

 Knowledge of the FORTRAN language

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34 NON-STANDARD MODELS USING FORTRAN

Prerequisites

 Before attempting to write any model, the

user should first ensure that the modeling

library model

 Perhaps by setting a gain to one or a time

constant to zero in an existing model

reduces it to the required form

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Model Requirements

 Each model must make different types of

computations at different stages in the

dynamic simulation

 A set of scalar variables are used to

communicate between PSS®E activities

 MODE

 KPAUSE

 MSTATE

 MIDTRM

 ITER, IFLAG and IBDOCU

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MODE

 Most critical of the variables

 MODE = 1: The model must initialize all of its state

variables and algebraic variables

 MODE = 2: The model must make all

computations needed to place time derivatives into

the DSTATE array

 MODE = 3: Governor models must compute the

present value of PMECH, exciter models must

compute the present value of EFD, stabilizers

model must compute the present value of

VOTHSG

 MODE = 4: The model must update the PSS®E

variable NINTEG indicating the highest STATE

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MODE

 Most critical of the variables

 MODE = 5: The model is being called by activity

DOCU in its reporting mode and must write out the

model data report

DYDA and must write out the data record

DOCU in its data checking mode and most

perform constant data checks and exceptions

must be reported

 MODE = 8: The model is being called to return

description of each CON and ICON data used by

the model

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KPAUSE

 Indicates the type of time step calculation

 KPAUSE = 0: Models are being called to make

their normal time step calculation

 KPAUSE = 1: Models are being called for the

value of simulation TIME equal to TPAUSE- (just

before a pause)p )

 KPAUSE = 2: Models are being called at the first

time step following a pause (TIME equal to

TPAUSE+)

 Most user-written models need not be

sensitive to the variable KPAUSE

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MSTATE

 Indicates the type of simulation

 MSTATE = 0: Standard state space dynamic

 MSTATE = 0: Standard state-space dynamic

simulation via activities STRT and RUN

 MSTATE = 1: Excitation system response ratioy p

 MSTATE = 2: Excitations system open circuit step

response

 MSTATE = 3: Governor response test

 MSTATE = 4: Extended term dynamic simulation

 MSTATE = 5: Dynamics data is present but no

initialization activity has been successful

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MIDTRM ITER and IFLAG

MIDTRM, ITER and IFLAG

 MIDTRM indicates whether state-space or

extended simulation

 MIDTRM = FALSE.: State-space simulation

 MIDTRM = TRUE.: Extended term simulation

 ITER indicates the number of iterations

the present value of simulation time

 IFLAG is usually sensed by models called y y

from TBLCNT and CONET

 IFLAG = FALSE.: The solution has not converged

 IFLAG = TRUE.: The solution has converged

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IBDOCU and KTRIP

 IBDOCU indicates the mode of operation

of DOCU and DYDA

 IBDOCU = 0: Process all models called

 IBDOCU > 0 : External bus number; only process

models at bus IBDOCU

 KTRIP must be set by any equipment y y

model which imposes network switching

 KTRIP = 0: No dual time step calculation required

 KTRIP = 1: In activities RUN and MRUN, one or

more data changes requiring a dual time step

calculation without affecting the network

admittance matrix

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 KTRIP must be set by any equipment

model which imposes network switching

 KTRIP = -1: In activities STRT and MSTR, one or

more load models changed the value of the g

constant admittance component of a load In

activities RUN and MRUN, one or more data

changes affecting the admittance matrix have

been implemented (no zero impedance line

switching)

 KTRIP = -3: In activities RUN and MRUN, one or

more data changes affecting the admittance matrix

have been implemented (at least one zero

impedance line switching)

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Model Calling Sequence Rules

 The SUBROUTINE statements for

plant-related models must be of the form

 MC: is the internal PSS®E machine array index

for the machine at which the model is being called

 ISLOT: is the internal PSS®E array allocation

table index for this model call

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 At the completion of each activity DYRE,

the array allocation table entries for each

plant-related model reference are set as

f ll

follows:

 STRTIN(1,ISLOT): contains the index of the first of

NC CONs used by the model

NS STATEs used by the model

NV VARs used by the model

 STRTIN(4 ISLOT): contains the index of the first of

NI ICONs used by the model

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Writing the Basic Model

 The steps in writing a PSS®E model are:

1 Determine the block diagram and/or the

differential and algebraic equations

2 Identify the state variables associated with the

model and determine a procedure for computing their time derivatives

3 Identify those quantities needed as inputs to the

model

4 Allocate locations in the CON, STATE, VAR

and/or ICON arrays as required

5 Write the model subroutine in FORTRAN or

FLECS

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Simple Excitation System

 Consider the following simple excitation

system DEMOEX

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 The first transfer function block involves

 Cross multiplying and rearranging

STATE (K)

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 The second transfer function block

involves one state variable E

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