SOLVING 
THE UNDER VOLTAGE PROBLEM IN 
SRI LANKAN NATIONAL GRID 
 
 
 
 
Nandike Pathirage 
SUPERVISED BY: DR. JAHAN C. PEIRIS 
 
A dissertation submitted in the partial fulfillment of the requirements for the degree of 
Master of Engineering 
 
 
Department of Electrical Engineering 
University Of Moratuwa 
Sri Lanka 
August 2001 
 
 
74482 
 CONTENTS 
Forward 
Preface and acknowledgements 
1 . Objectives & methodologies 
2. Introduction 
3. Basic concepts of voltage stability 
4. Voltage collapse in a transmission system 
5. Sri Lankan electrical power system 
6. Modeling approach.  
7. Results to show the existing problem 
8. Proposals to improve the voltage level 
9. Cost comparison of available options 
10. Implementation of proposals and results. 
11 . Conclusion 
12. References ... 
13. Appendices 
a. Collected Data 
b. Modeled Circuit Diagram 
 
Forward
To My Parents and My Wife
ii
PREFACE 
This dissertation includes the individual project details/results which has 
been completed as a part of Master of Engineering Program at 
Department of Electrical Engineering in University of Moratuwa, Sri Lanka 
in 2001 . 
In completion of this individual research project it was selected the " 
Electrical Power Transmission Network" in Sri Lanka as the area of study. 
This research is a attempt to model the existing system, as possible and 
' 
simulate the existing under voltage condition and.;to find the various 
remedial actions for this voltage collapse. 
How close is a system to voltage instability, may be measured in terms of 
physical quantities, such as load level, active power flow through a critical 
interface, and reactive power reserve. Considerations were given to 
possible contingencies such as; loss of reactive power sources, generating 
units and loss of critical lines. 
... 
In order to have a proper model and to find better solutions EMTDC/PCAD 
ver 3.0.0 personnel edition was used. This is a time-domain simulator and 
with that it was possible to have a better dynamic model which is very 
much closer to the existing one. 011< line plotting of time varying quantities, 
gave a great ease of modeling & checking the proposals. 
Ill 
ACKNOWLEDGEMENTS 
In completion of this research project many thanks go to Dr. Jahan Peiris 
Senior Lecturer ,Dept of Electrical Engineering in University of Moratuwa, 
who gave me his fullest support as my Project Supervisor. 
A big thank goes to Prof Rohan Lucas ; Head of the Department Dept of 
Electrical Engineering in University of Moratuwa and Dr. Ranjith Perera 
;senior lecturer of Department of Electrical Engineering in University of 
Moratuwa, who encouraged me much as the coordinator of this "Post 
Graduate Diploma I Master of Engineering Program". .1 
I would like to pay my sincere thanks to Ceylon Electricity Board and the 
people of it, who helped me in collecting data , and sharing their views and 
experiences with me during this approach. 
Also I would like to remind specially and pay my sincere to my beloved 
parents, my wife - Mrs. Devi Pathirage and.. her parents and our family 
members who gave me the fullest support in so many ways in completion of 
this research project. 
IV 
OBJECnvES AND ME1HOOOlOGIES 
1. OBJECTIVES AND METHODOLOGIES 
The main objective of this research study is to find a low cost solution for the 
existing under voltage situation in Sri Lankan power transmission system. 
In completion of this objective the following methodologies were used; 
a. Study the existing Sri Lankan Power transmission network with 
generator busses and load busses. 
b. Model this transmission syst~m in a comp~'r using computer 
aided software and have a dynamic model. 
c. Testing and tuning of the model with existing values. 
d. Implementation of proposals and produce the results . 
....