ABSTRACT
A single line contingency analysis and generator(s) outages were carried out on 330kV, 27-Bus
power network using MATPOWER 4.1 embedded in MATLAB to carry out fast decoupled load
flow studies in order to identify the voltage violation at various buses, determine power losses at
the transmission lines and to compute the performance indices. The performance indices were
further ranked in accordance with their severity index. Voltages less than 0.95pu were assumed
to be low voltages and voltages greater than 1.05pu were also assumed to be high voltages. We
also assumed that power losses greater than 5% are unacceptable. So a base case comparative
analysis of the load flow studies using three conventional methods showed that Gauss Seidel
could not converge in 0.93seconds and 1000 iterations, Newton Raphson converged in
0.15seconds and 6 iterations. However, Fast Decoupled Load Flow converged in 0.01second and
28 iterations. Hence, owing to its time for numerical iteration, its capacity to hold as many data
as possible and its merit of having a matrix alteration formula that can be incorporated and used
to simulate problem of contingencies involving power system equipment outages without
involving the inversion of the Jacobian matrix for all iteration, then FDLF is considered
extensively in the research work. Thereafter, outages of one and two generators are considered to
investigate their effect on the voltage drop and power loss. Further, N-1 secure was also carried
out on the transmission lines to investigate the performance indices of the lines which were later
ranked in accordance with their severity. The outcome of the simulations showed that at a time
when there was an outage of Kainji-GS, low voltages were found at Kano, Jos, Gombe, Kaduna,
Katampe, Oshogbo, Ajaokuta, New Haven, Aiyede, Ikeja-West, Onitsha, and Akangba buses.
And there were also power losses greater than 5% at Ikeja-West to Egbin, Ikeja-West to Benin,
Oshogbo to Benin, Kaduna to Shiroro, Kano to Kaduna, Jos to Kaduna and Jos to Gombe.
Moreso, it is pertinent to mention that the outage of Kainji GS and the outage of Calabar and
Sapele GS showed low voltages at the same buses. The single line contingency evaluation
carried out shows that transmission lines from Kaduna to Shiroro have the highest performance
indices and ranked number one. The ranking continued until the line with the least severity index
which was found to be Jebba GS to Jebba TS.
TABLE OF CONTENTS
Title page i
Approval page ii
Certification page iii
Dedication iv
Acknowledgment v
Abstract vii
Table of contents viii
List of tables x
List of figures xi
List of abbreviations xii
CHAPTER ONE
1.1 Introduction 1
1.2 Statement of research problem 1
1.3 The aim and objective of the study 2
1.4 Significance of the Study 2
1.5 Scope and Limitation 3
1.6 Project Arrangement 3
CHAPTER TWO
2.0. Literature review 5
2.10 Power System Stability 10
2.11 Overview of Contingency Analysis 10
2.12 Operating States of a Power System 13
2.13 States of Security Analysis 15
2.14 Power Flow Studies 18
2.15 Bus Classification in Power System 19
2.16 Power Flow Studies in System Design And Operation 21
2.17 Power System Outages 22
2.18 Line Loadability 22
ix
2.19 Types of Violations 23
2.20 Contingency Analysis Methods. 24
2.21 Contingency analysis by Sensitivity Factor. 24
2.22 The System Line Overload Index (SLOI) 25
2.23 Mathematical Model of Two-Bus System Transmission Line 25
2.24 Modeling of the Network 30
2.25 A.C Load Flow methods 31
2.26 Newton-Raphson’s Method Applied to P.F Problem 33
CHAPTER THREE
3.0 Data Collection and Methodology 41
3.1 Methodology 41
3.2 Mathematical Modeling of Fast Decoupled Load method 43
CHAPTER FOUR
4.0 Simulation And Results 58
4.1 Preparing Case Input Data 58
4.2 Solving The Case 58
4.3 Accessing The Results 58
4.4 Computing The Performance Indices 72
CHAPTER FIVE
5.0 Conclusion 75
5.1 Recommendation 75
5.2 Suggestion for further work 76
References 77
Appendix I 81
Appendix II 81
Appendix III 91
Appendix IV 96
x
CHAPTER ONE
1.1 INTRODUCTION
Contingency evaluation involves the study of the outage of components such as
transmission lines, generators, and investigation of the resulting effects on line power flows and
bus voltages of the remaining system [1]. Power system security evaluation is of paramount
importance in developing ways to maintain system operation when one or more components fail.
It represents an important tool to study the effect of component outages in power system security
during operation and planning. Contingencies may cause sudden and large changes in both the
configuration and the state of the system. It may result in severe violations of the operating
constraints.
Consequently, planning for contingencies forms an important aspect of secure operation
and contingency analysis allows the system to be operated defensively. Many of the problems
which occur in the power system can cause serious troubles within a short time if the operator
could not take fast corrective action. Therefore, modern computers are equipped with
contingency analysis programs which model the power system and are used to study outage
events and alert operators of potential overloads and voltage violations [1].
1.2 STATEMENT OF THE PROBLEM
The security of a power grid has become a focus owing to the vandalisation of the power
equipment which has affected the stability of Nigerian power system. Security appraisal is very
essential as it brings to lime light the state of the power system in the event of contingency. As a
matter of fact, the Nigeria power system has continued to suffer from inadequate generation and
transmission capacity despite the huge amount of money that has been invested into the sector.
2
The power demand is much higher than the generated power, and this has resulted to constant
load shedding and erratic power supply [2]. The transmission network is mostly radial and is not
sufficient to transfer additional power injected to the grid by the new power plants. Typical
steady-state system security demands the following: (i) No loss of load, (ii) bus voltages within
power quality bands, (iii) power flows in transmission line within thermal limits and (iv) system
operation at a safe margin from static voltage collapse.
1.3 THE AIM AND OBJECTIVES OF THE STUDY
The aim of the thesis is to carry out contingency analysis at the various buses and transmission
lines of Nigerian 330kV transmission grid.
The objectives of the study are as follow:
Ø Calculating the voltage magnitude in the network.
Ø Determining if the voltage variations are undesirable and not within the stipulated regulatory
limit of ±5% of the declared voltage at the each of the buses of the transmission network.
Ø Determining the performance indices of transmission lines outage so that network
weaknesses can be identified.
Ø Ranking the contingency according to its severity for priority attention of the
System Engineer.
Ø Determining the effect of loss of one or more generators on the power system.
Ø Identifying the effect of loss of transmission lines on the performance of the power system.
3
1.4 SIGNIFICANCE OF THE STUDY
Contingency evaluation is used as a study tool for the off-line analysis of contingency
events, and as a tool to show operators what would be the effects of any failure or outage. This
will in no small measure help the system planners with the best location for new transmission
lines. Steady state power system insecurity such as transmission lines being overloaded causes
transmission line components outages which may lead to complete blackout. The power system
operator must know the system state at any instant. The contingency analysis is helpful in
predicting the contingencies that make system violations and rank the contingencies according to
their relative severity. Contingency evaluation is useful in the network design stages and for
programmed maintenance or network expansion works to detect network weaknesses. However,
in a risk-prone and beleaguered nation such as ours, a routine contingency evaluation of the
power network is of paramount importance in order to mitigate the undesirable effect of the
vandalisation of the power equipment occasioned by the crisis in the country. It will help to alert
the power systems operators and planners about the danger that lies ahead on the outage of a
transmission line and generator(s).
1.5 SCOPE OF THE STUDY
The thesis is limited to the study of contingency evaluation of 330kV transmission grid, 27- bus
of the Nigerian network.
1.5 PROJECT ARRANGEMENT
The work carried out in this thesis is arranged in five chapters. Chapter one introduces the
topic and briefly looked at the: statement of the problem, the aim and objectives of study, scope
of the study and the significance of the study.
4
Chapter two dwells on the review of literature by different authors that have worked on similar
topic. It goes further to look at the : Power system stability, contingency analysis overview,
operating states of a power system, security analysis states, power flow studies, bus classification
in power system, power flow studies in system design and operation, power system outages, line
loadability, types of violations, contingency analysis methods, contingency analysis by
sensitivity factor, the system line overload index(SLOI) , mathematical model of two-bus system
transmission line, modeling of the network and AC load flow methods.
Chapter three elucidates data collection and methodology and chapter four looks at simulation
and discussion of results. Finally, chapter five concludes the thesis with recommendations and
suggestions for future work.
Do you need help? Talk to us right now: (+234) 08060082010, 08107932631 (Call/WhatsApp). Email: [email protected].
IF YOU CAN'T FIND YOUR TOPIC, CLICK HERE TO HIRE A WRITER»
