Introduction to power system analysis

INTRODUCTION TO POWER SYSTEM
ANALYSIS
Contents:
 Overview
 Function of power system analysis
 Need for Power System Analysis
Kongunadu College of Engineering & Technology Introduction to Power System Analysis Prepared by,
Mrs.S.Revathi 1

Overview of Power System Analysis
 A power system consists of generation, transmission and
distribution system.
 The components of the power systems are generators,
transformers, transmission lines, distribution lines, loads
and compensating devices like shunt, series, and static VAR
compensators.
 In order to maintain power system, the bulk power has to
be transmitted through transmission and distribution lines
to the consumers safely and economically.
 The evaluation of power system is called power system
analysis
 In monitoring power system analysis, we are mainly
dealing with power or load flow analysis, short circuit
analysis and stability analysis.
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The functions of power system analysis are:
To monitor the voltage at various buses, real and
reactive power flow between buses.
To design the circuit breakers.
To plan future expansion of the existing system.
To analyze the system under different fault
conditions (3 fault-G, L-L,L-L-G faults).
To study the ability of the system for larger
disturbances (sudden application of large load).
To study the ability of the system for small
disturbances (routine or small load changes).
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 The most important characteristic of the power
system is that it can neither store energy nor is it
the ultimate source of energy.
 The system only converts the energy available
from natural sources in to the electrical form and
then handles it in an efficient manner.
 The natural sources of energy are the following:
Coal, Water flow, Uranium and thorium( fissible
materials) , Fossil fuel(oil, natural gas), Wind,
Tidal, Solar, Biogas etc.
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Mrs.S.Revathi

Need For System Analysis in planning and
operation of power system
 Operational planning covers the whole period ranging from
the incremental stage of system development.
 The system operation engineers at various points like area,
space, regional and national load despatch deals with the
despatch of power.
 Power balance equation is
𝑃 𝐷 = 𝑃𝐺𝑖
𝑁
𝑖=1 , i=1,2,3,…N
Total demand=Sum of the real power generation
i.e., the generation should be such a way that to meet out the
required demand.
 When this relation is satisfied, it gives good economy and
security.
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Mrs.S.Revathi

 The operation of power system must be reliable and
uninterrupted.
 The reliability of power system implies more than
availability of power.
 The loads must be fed at constant voltage and
frequency.
 Electrical areas are large in size. So planning for
future expansion of a power system is essential.
 More network data must be collected for planning a
power system network.
 For planning of power system; power system
engineers use computer programming.
 Importance of power system planning and operational
analysis covers the maintenance of generation,
transmission and distribution facilities.
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Mrs.S.Revathi

Steps to be followed:
 Planning of power system
 Implementation of the plans
 Monitoring the system
 Compare with the results
 If no undesirable deviation occurs, then directly go to planning of
system
 If undesirable deviation occurs, then take corrective action (i.e.,
increase or decrease) and then go to the planning of the system.
 For planning and operation of power system, the following
analyses are more important.
Load flow analysis
Short circuit analysis
Transient analysis
 To identify the potential deficiencies of the proposed system, the
cause of the equipment failure and malfunction can be
determined through a system study.
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Load Flow Analysis:
 Normally, electrical power systems operate in their steady
state mode and the basic calculation required to determine
the characteristics of this state is called as load flow.
 Power flow studies are used to determine the voltage,
current, active and reactive power flows in a given power
system.
 These conditions may cause equipment overloads or
unacceptable voltage levels.
 The study results can be used to determine the optimum size
and location of the capacitors for power factor improvement.
 The results of the power flow analysis are the starting point
for stability analysis.
 This is also needed to evaluate the effect of different loading
conditions of an existing system.
9Kongunadu College of Engineering & Technology Introduction to Power System Analysis Prepared by,
Mrs.S.Revathi

Short Circuit Studies
 Short circuit in any part of a power system causes as
manifold increase in current and creates an abnormal or
faulty condition in the system.
 The short circuit studies are performed to determine the
magnitude of the current flowing throughout the power
system at various time intervals after a fault.
 The magnitude of current flowing through the power
system after a fault varies with time until it reaches a
steady state conditions.
 The objective of short circuit analysis is to precisely
determine the currents and voltages at different locations
of the system corresponding to different types of faults,
such as three phase to ground fault, line to ground fault,
line to line fault, double line to ground fault and open
conductor fault.
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Transient Stability Analysis
 The ability of the power system consisting of two or
more generators to continue to operate after a change
occurs on the system is a measure of the stability.
 In power system, the stability depends on the power
flow pattern, generator characteristics, system
loading level and line parameters etc.
 There are two forms of instability in the power
system such as the loss of synchronism between
synchronous machines and stalling of asynchronous
loads.
 The stability may be divided in to steady state and
transient stability.
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 The steady state stability is defined as the ability of the power
system to remain in synchronism following relatively slow load
change or continual changes in generation and the switching
out of lines.
 Transient stability is defined as the ability of the power system
to remain in synchronism under large disturbance conditions,
such as fault and switch operations. The maximum power
transfer limit is less than that of the steady state condition.
 Transient stability studies are conducted when new generating
and transmitting facilities are planned. The studies are helpful
in determining the nature of relay system needed, critical
clearing time of circuit breakers, voltage level and transfer
capability between systems etc.
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Conclusion:
 The various steps involved in power system planning
and operation in listed clearly.
References:
1. Hadi Saadat, ‘Power System Analysis’, Tata McGraw Hill Education Pvt. Ltd., New Delhi,
21st reprint, 2010.
2. Kundur P., ‘Power System Stability and Control, Tata McGraw Hill Education Pvt. Ltd., New
Delhi, 10th reprint, 2010.
3. Pai M A, ‘Computer Techniques in Power System Analysis’, Tata Mc Graw-Hill Publishing
Company Ltd., New Delhi, Second Edition, 2007.
4. J. Duncan Glover, Mulukutla S. Sarma, Thomas J. Overbye, ‘ Power System Analysis &
Design’, Cengage Learning, Fifth Edition, 2012.
5. Olle. I. Elgerd, ‘Electric Energy Systems Theory – An Introduction’, Tata McGraw Hill
Publishing Company Limited, New Delhi, Second Edition, 2012.
6. C.A.Gross, “Power System Analysis,” Wiley India, 2011.
7. M.Jeraldin Ahila “Power System Analysis”, Lakshmi Publications, Chennai, Eleventh
Edition 2017.
8. Other web sources
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Introduction to power system analysis

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