OPTIMAL PLACEMENT OF AUTOMATED SWITCH IN DISTRIBUTION NETWORK WITH CUSTOMER INTERRUPTION COST (CASE STUDY: HAWASSA DISTRIBUTION)

Abstract

Power system is to provide an adequate and secure electrical supply to its customers as economically as possible with reasonable level of reliability. In distribution system, reliability and cost of Energy not supply (power loss) are the major issues for the consumers and utility. Hawassa distribution feeder has repeated power interruption difficulties. The main causes of interruptions are earth fault (EF) and short circuit (SC). The intended outage such as operation and maintenance purpose of the distribution system is another causes of distribution planned outage. The feeder’s System Average Interruption Frequency Index (SAIFI), System Average Interruption Duration Index (SAIDI), Energy not supply (ENS) and power loss are 123.9 interruptions per customer per year, 136.8 hours per customer per year, 1843.2 MWhr/yr. and 409.2 Kw, respectively. The feeder is not reliable by the standard of Ethiopian Electric Agency (EEA) which has set SAIFI as equal to 20 interruptions per customer per year and SAIDI which is around 25 hours per customer per year. Optimal placement of automated switches (auto recloser) can significantly improve reliability of the system, reduce Energy not supply (power losses) and decrease Expected Interruption Cost (ECOST) of the system. Therefore, the main aim of the study is to improve the reliability of the distribution system by optimal placement of automated switch (auto recloser). The economic impact of power interruption in both the utility and customers is significant, thus makes placement of auto recloser on selected feeder, improve distribution system reliability and reduce cost of energy not supply (power loss). Optimal placement of auto recloser is determined by the Grasshopper optimization Algorithm (GOA) technique using MATLAB code and the reliability indices evaluated by using etap 16.0.0 and compared with PSO (particle swarm optimization).The reliability of distribution system has improved by employing optimal placement of auto recloser. Therefore, the overall reliability of Hawassa city distribution feeder 12 indices SAIFI by 88.9 %,SAIDI by 76.3% , EENS by 76.5 % , power loss by 70.5 % and ECOST by 55%; had improved as compared with the base case system.