DISTRIBUTION SYSTEM RELIABILITY ENHANCEMENT BY ASSET MANAGEMENT STRATEGIES FOR NETWORK RECONFIGURATION (ACASE STUDY OF NEKEMTE CITY DISTRIBUTION NETWORK

Abstract

Assets aging, corrosion, deterioration and slow replacement rate causes derating of the distribution system reliability and frequently damage and burn for the assets. They cause system power outage in radial distribution system in which a single power supplies the whole system. Thus, the objective of the study is to enhance the distribution system reliability by asset management strategies for network reconfiguration. Nekemte city is located in western Ethiopia, Oromia Region, East Wollaga Zone at latitude 9°5′N, and longitude of 36°33′E . Nekemte city distribution network is selected as a case study area in order to collect and analysis asset management strategy (in appendix (A) and reliability data (Appendix (B). The study is limited to circuit breakers (15Kv), transformers (15/0.4Kv) and OH lines (15Kv) assets. Age and health condition data’s of assets are collected to evaluate each asset’s health index. Health index is used to decide the proper maintenance and replacement strategy for present and future. As the result of asset management strategy, two (2)circuit breakers, seventy seven(77) transformers and forty point one (40.1) km of distribution overhead line requires replacement strategy and five (5) transformers and point seven(0.7) Km of distribution overhead line requires preventive maintenances. The placement and populations of automatic reclosers, sectionalizing switches and automation switches are optimized using Genetic Algorithm (GA) and Particle Swarm Optimization (PSO) for network reconfiguration. Since, GA is better for local optima solution and PSO is better for Global Optima solution, it is better if the results of both compared. In this thesis using PSO is better result than GA result. GA and (PSO) are developed in MATLAB R2016a software as shown in Appendix (C) and Appendix (D) respectively. PSO results five (5) sectionalizing switches, seven (7) Automations switches and eighteen (18) reclosers and their respective position in distribution line. DIgSILENT Power Factory 15.1.7 software is used to demonstrate and simulate distribution system to assess reliability Index. Using Asset management strategy for network reconfiguration the distribution system, SAIFI is improve by 84.56 percentage from 87.2 to 13.461 per customer year, SAIDI is improved by 98.27 percentages from 5889.86 to 101.565 hours per customer year. ENS improved by 98.24 percentages from 119.407 to 3.913MWh per year, and EIC improved by 98.24 percentages from 11.942 to 0.21 and save 11.732 M$ in a year. These work have Payback period of 1.742, therefore it is economically feasible if implemented