RELIABILITY IMPROVEMENT IN MEDIUM VOLTAGE DISTRIBUTION SYSTEM A dissertation submitted to the Department of Electrical Engineering, University of Moratuwa In partial fulfilment of the requirements for the Degree of Master of Engineering By S. BOGAHA WATTE Supervised By: Prof. Ranjit Perera Department of Electrical Engineering University of Moratuwa, Sri Lanka 2006 86329 Abstract The reliability study in Electricity network in Sri Lanka is seldom carried out. Moreover in areas where this is carried out, it is limited to calculate SAIFI; SADI by means of using the failure data collected from the consumer service centres. This is not enough to evaluate and improve the reliability levels of the network. The failures of Medium Voltage lines and equipment result in revenue losses to the utilities as well as to consumers. In Sri Lanka the utilities are concerned about collection of revenue but not much about reliability issues. This study focuses on the following: 1. Introduction of Reliability concepts to utilities in Sri Lanka 2. Development of a computer based model to calculate reliability levels 3. Proposing methods to improve the reliability such as better maintenance practiced and policies, augmentation of lines and switching arrangements. The methodology in this project was developed using the MS Excel Programme for Medium Voltage Network of Consumer Service Centre (CSC) Area, Boralesgamuwa and tested for that of Fulleorton CSC Area, Kalutara. This methodology could be used for any part of the Medium Voltage Netwerk and extended to Localised Low Voltage Systems for evaluation and improvement of reliability. DECLARATION The work submitted in this dissertation is the result of my own investigation, except where otherwise stated. It has not already been accepted for any degree, and is also not being concurrently submitted for any other degree. i s.~watte Date: 30.1 1.2005 I endorse the declaration by the candidate. Pro~ .. ,. " . .;" ..... . :. ~ .. "' ~ / ACKNOWLEDGEMENT First I thank very much Prof. Rangit Perera without whose guidance, suppot1 and encouragement, beyond his role of project supervisor this achievement would not be end with this final dissertation successfully. I take this opportunity to extend my sincere thanks to Mr. Maxwell Tissera fom1er AGM Distribution and Consumer Services, Mrs. Badra Jayaweera AGM (Distribution Operations-Rl ), Mr. Nihal Wickramasooriya AGM (Distribution Operations-R4) of . t Ceylon Electricity Board (CEB) and Dr. Jihan Pieris former Course Coordinator for encouraging me to follow this course. I also thank Engineers in the Distribution Planning Branch Region 01 for facilitating me with software packages etc. of reliability and System Planning Engineer and two Electrical Superintends of System Planning Unit and the DGM of Western Province South 0 I and two Area Engineers and Electrical Superintends of Ratmalana and Kalutara of CEB for providing me the facilities and petmission to use details and data of area break down and distribution Network. ..~ " It is a great pleasure to remember the kind cooperation of all the colleagues in Post ' ; ' Graduate program and all family members for backing me from start to end of this course. ~ -;.~ ... .,., _,.~ .... iii Declaration Abstract Acknowledgement Contents Chapters 1. Introduction 1.1 Background Contents 1.2 Distribution System Reliability 1.3 Motivation 1.4 Goal 2. Problem Statement 3. Proposed Solution 3.1 Features of Solution Approach 3.2 Algorithm for reliability Improvement model 4. Theoretical Developments I II 111 IV 01 01 05 06 07 10 13 4.1 Importance of Reliability Evaluation 16 4.2 The Method used in Power System Reliability Evaluation 16 4.3 The reliability Indices 17 4.4 System Performance 21 4.5 Modelling a feeder for evaluation reliability 22 5. Application of the Proposed Method 5.1 Sample System for reliability evaluation 27 5.2 Collection of Data 29 6. Results and Analysis 6.1 Developing the Methodology 6.2 Testing of the Model Developed 7. Conclusion 7.1 Conclusions, Remarks and Discussion 7.2 Recommendations for Future Research References Appendix 6A Appendix 68 Appendix 6C Appendix 60 A~ " 34 39 41 _.; 44 . 47~ --ยท- v 48 55 57 66 ,r"' I\