**EE2404 POWER SYSTEM SIMULATION LABORATORY L T P C**

**0 0 3 2**

**AIM**

To acquire software development skills and experience in
the usage of standard packages

necessary for analysis and simulation of power system
required for its planning, operation and

control.

**OBJECTIVES**

i. To develop simple C programs for the following basic
requirements:

a) Formation of bus admittance and impedance matrices and
network solution.

b) Power flow solution of small systems using simple
method, Gauss-Seidel P.F.

method.

c) Unit Commitment and Economic Dispatch.

II. To acquire experience in the usage of standard
packages for the following

analysis / simulation / control functions.

d) Steady-state analysis of large system using NRPF and
FDPF methods.

e) Quasi steady-state (Fault) analysis for balanced and
unbalanced faults.

f) Transient stability simulation of multimachine power
system.

g) Simulation of Load-Frequency Dynamics and control of
power system.

1. Computation of Parameters and Modelling of
Transmission Lines

2. Formation of Bus Admittance and Impedance Matrices and
Solution of Networks.

3. Load Flow Analysis - I : Solution of Load Flow And
Related Problems Using

Gauss-Seidel Method

81

4. Load Flow Analysis - II: Solution of Load Flow and
Related Problems Using Newton-

Raphson and Fast-Decoupled Methods

5. Fault Analysis

6. Transient and Small Signal Stability Analysis:
Single-Machine Infinite Bus System

7. Transient Stability Analysis of Multimachine Power
Systems

8. Electromagnetic Transients in Power Systems

9. Load – Frequency Dynamics of Single- Area and Two-Area
Power Systems

10. Economic Dispatch in Power Systems.

**TOTAL : 45 PERIODS**

**DETAILED SYLLABUS**

**1. COMPUTATION OF PARAMETERS AND MODELLING OF TRANSMISSION**

**LINES**

**Aim**

(i) To determine the positive sequence line parameters L
and C per phase per kilometer of a

three phase single and double circuit transmission lines
for different conductor

arrangements.

(ii) To understand modelling and performance of short,
medium and long lines.

**Exercises**

Computation of series inductance and shunt capacitance
per phase per km of a three phase line

with flat horizontal spacing for single stranded and
bundle conductor configuration.

Computation of series inductance and shunt capacitance
per phase per km of a three phase

double circuit transmission line with vertical conductor
arrangement with bundle conductor.

Computation of voltage, current, power factor, regulation
and efficiency at the receiving end of a

three phase
Transmission line when the voltage and power at the sending end are given. Use ÐŸ

model.

Computation of receiving end voltage of a long
transmission for a given sending end voltage and

when the line is open circuited at receiving. Also
compute the shunt reactor compensation to

limit the no load receiving end voltage to specified
value.

Determination of the voltage profile along the long
transmission line for the following cases of

loading at receiving end (i) no load (ii) rated load
(iii) surge impedance loading and (iv) receiving

end short circuited.

**2. FORMATION OF BUS ADMITTANCE AND IMPEDANCE MATRICES AND SOLUTION OF**

**NETWORKS**

**AIM**

To understand the formation of network matrices, the bus
admittance matrix

**Y**and the bus
impedance matrix

**Z**of a power network, to effect certain required changes on these matrices and to
obtain network solution using these matrices.

82

**Exercises**

**2.1**Write a program in C language for formation of bus admittance matrix

**Y**of a power network

using the “Two-Rule Method”, given the data pertaining to
the transmission lines, transformers

and shunt elements. Run the program for a sample 6 bus
system and compare the results with

that obtained using a standard software.

**2.2**Modify the program developed in 2.1 for the following:

(i) To obtain modified

**Y**matrix for the outage of a transmission line, a
Transformer and a shunt element.

(ii) To obtain network solution

**V**given the current injection vector**I**
(iii) To obtain full

**Z**matrix or certain specified columns of**Z**matrix.
Verify the correctness of the modified program using 6
bus sample system

*

**2.3**Write a program in C language for forming bus impedance matrix**Z**using
the “Building Algorithm”.

* Optional (not mandatory)

**EXPERIMENT 3**

**LOAD FLOW ANALYSIS - I : SOLUTION OF LOAD FLOW AND RELATED PROBLEMS USING**

**GAUSS-SEIDEL METHOD**

**Aim**

(i) To understand, the basic aspects of steady state
analysis of power systems that are

required for effective planning and operation of power
systems.

(ii)To understand, in particular, the mathematical
formulation of load flow model in complex form

and a simple method of solving load flow problems of
small sized system using Gauss-Seidel

iterative algorithm

**Exercises**

**3.1**Write a program in c language for iteratively solving load flow equations using

Gauss-Seidel method with provision for acceleration
factor and for dealing

with P-V buses. Run the program for a sample 6 bus system
(Base case)

and compare the results with that obtained using a
standard software.

**3.2**Solve the “Base case” in 3.1 for different values of acceleration factor, draw the convergence

characteristics “Iteration taken for convergence versus
acceleration factor” and determine the

best acceleration factor for the system under study.

**3.3**Solve the “Base Case” in 3.1 for the following changed conditions and comment on the results

obtained, namely voltage magnitude of the load buses and
transmission losses:

(i) Dropping all shunt capacitors connected to network

(ii) Changing the voltage setting of generators Vgi over the range 1.00 to 1.05

(iii) Changing the tap setting of the transformers, ai, over the range 0.85 to 1.1

**3.4**Resolve the base case in 3.1 after shifting generation from one generator bus to another

generator bus and comment on the MW loading of lines and
transformers.

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**4. LOAD FLOW ANALYSIS – I: SOLUTION OF LOAD FLOW AND RELATED**

**PROBLEMS USING NEWTON-RAPHSON AND FAST DECOUPLED**

**METHODS**

**Aim**

(i) To understand the following for medium and large
scale power systems:

(a) Mathematical formulation of the load flow problem in
real variable form

(b) Newton-Raphson method of load flow (NRLF) solution

(c) Fast Decoupled method of load flow (FDLF) solution

(ii) To become proficient in the usage of software for
practical problem solving in the areas of

power system planning and operation.

(iii) To become proficient in the usage of the software
in solving problems using Newton-

Raphson and Fast Decoupled load flow methods.

**Exercises**

**4.1**Solve the load flow problem (Base case) of a sample 6 bus system using Gauss-Seidel, Fast

Decoupled and Newton-Raphson Load Flow programs for a
mismatch convergence tolerance of

0.01 MW, plot the convergence characteristics and compare
the convergence rate of the three

methods.

**4.2**Obtain an optimal (minimum transmission loss) load flow solution for the Base case loading of 6

bus sample system by trial and error approach through repeated
load flow solutions using Fast

Decoupled Load Flow package for different combinations of
generator voltage settings,

transformer tap settings, and reactive power of shunt
elements.

**4.3**Carry out contingency analysis on the optimal state obtained in 4.2 for outage of a transmission

line using FDLF or NRLF package.

**4.4**Obtain load flow solutions using FDLF or NRLF package on the optimal state obtained in 4.2 but

with reduced power factor (increased Q load) load and
comment on the system voltage profile

and transmission loss.

**4.5**Determine the maximum loadability of a 2 bus system using analytical solution as well as

numerical solution using FDLF package. Draw the P-V curve
of the system.

**4.6**For the base case operating state of the 6 bus system in 4.1 draw the P-V curve for the weakest

load bus. Also obtain the voltage Stability Margin (MW
Index) at different operating states of the

system.

**4.7**For the optimal operating state of 6 bus system obtained in 4.2 determine the

Available Transfer Capability (ATC) between a given
“source bus” and a given “s

**4. FAULT ANALYSIS**

**AIM**

To become familiar with modelling and analysis of power
systems under faulted condition and to

compute the fault level, post-fault voltages and currents
for different types of faults, both

symmetric and unsymmetric.

84

**Exercises**

**5.1**Calculate the fault current, post fault voltage and fault current through the branches for a three

phase to ground fault in a small power system and also
study the effect of neighbouring system.

Check the results using available software.

**5.2**Obtain the fault current, fault MVA, Post-fault bus voltages and fault current distribution for single

line to ground fault, line-to-line fault and double line
to ground fault for a small power system,

using the available software. Also check the fault
current and fault MVA by hand calculation.

**5.3**Carryout fault analysis for a sample power system for LLLG, LG, LL and LLG faults and prepare

the report.

**6. TRANSIENT AND SMALL-SIGNAL STABILITY ANALYSIS: SINGLE**

**MACHINE-INFINITE BUS SYSTEM**

**Aim**

To become familiar with various aspects of the transient
and small signal stability analysis of Single-

Machine Infinite Bus (SMIB) system.

**Exercises**

For a typical power system comprising a generating,
step-up transformer, double-circuit transmission

line connected to infinite bus:

**Transient Stability Analysis**

**6.1**Hand calculation of the initial conditions necessary for the classical model of the

synchronous machine.

**6.2**Hand computation of critical clearing angle and time for the fault using equal area

criterion.

**6.3**Simulation of typical disturbance sequence: fault application, fault clearance by opening of one

circuit using the software available and checking
stability by plotting the swing curve.

**6.4**Determination of critical clearing angle and time for the above fault sequence through trial and

error method using the software and checking with the
hand computed value.

**6.5**Repetition of the above for different fault locations and assessing the fault severity with respect

to the location of fault

**6.6**Determination of the steady-state and transient stability margins.

**Small-signal Stability Analysis:**

**6.7**Familiarity with linearised swing equation and characteristic equation and its roots,

damped frequency of oscillation in Hz, damping ratio and
undamped natural

frequency.

**6.8**Force-free time response for an initial condition using the available software.

**6.9**Effect of positive, negative and zero damping.

85

**7. TRANSIENT STABILITY ANALYSIS OF MULTIMACHINE POWER SYSTEMS**

**AIM**

To become familiar with modelling aspects of synchronous
machines and network, state-of-the-art

algorithm for simplified transient stability simulation,
system behaviour when subjected to large

disturbances in the presence of synchronous machine
controllers and to become proficient in the

usage of the software to tackle real life problems
encountered in the areas of power system planning

and operation.

**EXERCISES**

For typical multi-machine power system:

**7.1**Simulation of typical disturbance sequence: fault application, fault clearance by opening of a

line using the software available and assessing stability
with and without controllers.

**7.2**Determination of critical clearing angle and time for the above fault sequence through trial

and error method using the software.

**7.3**Determination of transient stability margins.

**7.4**Simulation of full load rejection with and without governor.

**7.5**Simulation of loss of generation with and without governor.

**7.6**Simulation of loss of excitation (optional).

**7.7**Simulation of under frequency load shedding scheme (optional).

**8. ELECTROMAGNETIC TRANSIENTS IN POWER SYSTEMS**

**Aim**:

To study and understand the electromagnetic transient
phenomena in power systems caused due to

switching and faults by using Electromagnetic Transients
Program (EMTP) and to become proficient

in the usage of EMTP to address problems in the areas of
over voltage protection and mitigation

and insulation coordination of EHV systems.

**Exercises**

Using the EMTP software or equivalent

Simulation of single-phase energisation of the load
through single-phase pi-model of a transmission

line and understanding the effect of source inductance.

**8.1**Simulation of three-phase energisation of the load through three-phase pi-model of a

transmission line and understanding the effect of pole
discrepancy of a circuit breaker.

**8.2**Simulation of energisation of an open-ended single-phase distributed parameter transmission

line and understanding the travelling wave effects.

**8.3**Simulation of a three-phase load energisation through a three-phase distributed parameter

line with simultaneous and asynchronous closing of
circuit breaker and studying the effects.

**8.4**Study of transients due to single line-to-ground fault.

**8.5**Computation of transient recovery voltage.

86

**9. LOAD-FREQUENCY DYNAMICS OF SINGLE-AREA AND TWOAREA**

**POWER SYSTEMS**

**Aim**

To become familiar with the modelling and analysis of
load-frequency and tie-line flow dynamics of a

power system with load-frequency controller (LFC) under
different control modes and to design

improved controllers to obtain the best system response.

**Exercises**

**9.1**Given the data for a Single-Area power system, simulate the load-frequency dynamics (only

governor control) of this area for a step load
disturbance of small magnitude, plot the time

response of frequency deviation and the corresponding
change in turbine power. Check the

value of steady state frequency deviation obtained from
simulation with that obtained by hand

calculation.

**9.2**Carry out the simulation of load-frequency dynamics of the Single-Area power system in 9.1

with Load-frequency controller (Integral controller) for
different values of KI
(gain of the

controller) and choose the best value of KI to give an “optimal” response with
regard to peak

over shoot, settling time, steady-state error and
Mean-Sum-Squared-Error. [

**9.3**Given the data for a two-area (identical areas) power system, simulate the load-frequency

dynamics (only governor control) of this system for a
step load disturbance in one area and

plot time response of frequency deviation, turbine power
deviation and tie-line power deviation.

Compare the steady-state frequency deviation obtained
with that obtained in the case of

single-area system.

**9.4**Carry out the simulation of load-frequency dynamics of two-area system in 9.3 for the following

control modes:

(i) Flat tie-line control

(ii) Flat frequency control

(iii) Frequency bias tie-line control

and for the frequency bias Tie-line control mode,
determine the optimal values of

gain and frequency bias factor required to get the “best”
time response.

**9.5**Given the data for a two-area (unequal areas) power system, determine the best controller

parameters; gains and bias factors to give an optimal
response for frequency deviation and tieline

deviations with regard to peak overshoot, settling time,
steady-state error and Mean-

Sum-Squared-Error.

**10. ECONOMIC DISPATCH IN POWER SYSTEMS**

**Aim**

(i) To understand the basics of the problem of Economic
Dispatch (ED) of optimally

adjusting the generation schedules of thermal generating
units to meet the system

load which are required for unit commitment and economic
operation of power

systems.

(ii) To understand the development of coordination
equations (the mathematical model

for ED) without and with losses and operating constraints
and solution of these

equations using direct and iterative methods

87

**Exercises**

**10.1.**Write a program in ‘C’ language to solve economic dispatch problem of a power system

with only thermal units. Take production cost function as
quadratic and neglect

transmission loss.

**10.2.**Write a program in ‘C’ language to solve economic dispatch problem of a power system.

Take production cost as quadratic and include
transmission loss using loss co-efficient.

Use Î»-iteration algorithm for solving the
co-ordination equations.

**10.3.**Determine using the program developed in exercise 10.1 the economic generation

schedule of each unit and incremental cost of received
power for a sample power system,

for a given load cycle.

**10.4.**Determine using the program developed in exercise 10.2 the economic generation

schedule of each unit, incremental cost of received power
and transmission loss for a

sample system, for the given load levels.

**10.5.**Apply the software module developed in 10.1 to obtain an optimum unit commitment

schedule for a few load levels.

**REQUIREMENT FOR A BATCH OF 30 STUDENTS**

**S.No. Description of Equipment Quantity**

**required**

1. Personal computers (Pentium-IV, 80GB, 512

MBRAM)

25

2. Printer laser 1

3. Dotmatrix 1

4. Server (Pentium IV, 80GB, 1GBRAM) (High

Speed Processor)

1

5. Software: E.M.T.P/ETAP/CYME/MIPOWER

/any power system simulation software

5 licenses

6. Compliers: C, C++, VB, VC++ 25 users