RELIABILITY ASSESSMENT AND ENHANCEMENT OF POWER DISTRIBUTION NETWORK BY OPTIMAL PLACEMENT OF SECTIONALIZERS (CASE:-STUDY ON ALABA DISTRIBUTION SUBSTATION

Abstract

Electrical power distribution unreliability reduces user power consumption and seriously affects day today activities. This thesis tries to assess reliability and mitigation strategy of the Alaba distribution substation which has faced frequent power interruption problem. 15kv Durame distribution feeder, according to the last three years consecutive data, has high interruption problem among the four feeders of Alaba distribution substation. The interruptions mainly caused by the earth fault and short circuit. There are also planned outages for operation and maintenance purpose. The feeder‟s System Average Interruption Frequency Index (SAIFI) and System Average Interruption Duration Index (SAIDI) are 167.79 interruptions per customer per year and 218.93 hours per customer per year, respectively calculated by Monte Carlo simulation. The Feeder is not reliable compared with Ethiopia Electric Agency (EEA) standard which has set SAIFI as equal to 20 interruptions per customer per year and SAIDI which is around 25 hours per customer per year. It is required to find best solution for enhancement of reliability. Therefore, the objective of the study is to enhancement the reliability of the distribution system by determination and optimal placement of sectionalizer switches by using whale optimization algorithm techniques and compared with particle swarm optimization. The historical outage interruption data of years 2019 to 2021G.C has been used as a base year. The reliability indices calculated by Monte Carlo simulation Algorithm techniques have been done with the help of Matlab 2016a software. Electrical Transient Analysis programs (ETAPS 16.0.0) software has been used for modeling existing system. The reliability of distribution system has improved by optimal placement sectionalizer switches. Therefore, the overall reliability of Durame city feeder indices SAIFI by 85.98% (Decrease from 167.79 to 23.52 interruption per customer per year), SAIDI by 80.93% (Decrease from 218.93 to 41.73 hours per customers per year) EENS by 67 % (Decrease from 2,224.79 to 734.199 Megawatt hours per year), and Cost of EENS by 66.44% (Decrease From 4,449,590.4 to 1,468,398 Birr per year) has been improved as compared with the existing system. The economic analysis indicates that the selected solution results in a cost saving of 2,981,192.4 ETB per year from the unsold energy of one feeder only with 0.79 year payback period investment.