Reliability Analysis and Improvement of Electric Power Distribution System Using Network –Reconfiguration: A Case Study of Debre Berhan Power Distribution System.

Abstract

A stable and reliable electric power supply system is an inevitable pre-requisite for the technological and economic growth of any nation. Due to this, utilities must strive and ensure that the customers are getting the reliable power supply. In this thesis the reliability of Debre Berhan Distribution System was done on both 15 and 33kV system to assess the performance of the existing system. Moreover predictive reliability analysis for the future system considering optimal placement of switches have been analyzed. For predictive reliability analysis fuzzy logic based optimization was selected and applied which delivers optimal number and placement of sectionalizer switches. The installation of sectionalizer switches in strategic places reduces the outage time in case of abnormal conditions and improves the reliability of the network. This alternative which gives low system average interruption duration index (SAIDI), system average interruption frequency index (SAIFI) and customer average interruption duration index (CAIDI) are being assessed and considered. The reliability analysis indicated that of 15kV of Sheno feeder could be further improved by installation of optimal placement of switches and ETAP software simulation has also been used for both initial optimal network configurations. As the result of the optimal placement of switches the number and location of sectionalize switches SAIFI and SAIDI are reduced from 145.2115faiure / cust.yr, 322.0554 hr./cust.yr to 132.7942failure / cust.yr & 266.8047 hr./cust.yr. From the test results, the proposed technique presents better interruption cost in comparison with that of the existing system 64,806.06 $/yr. to 57,346.57 $ / yr. (11.5 %) reduction along with improvement in reliability indices. The method is implemented and tested on Sheno feeder of Debre Berhan town distribution network. Results of both initial and optimal configuration of expected energy not supplied (EENS) was improved from 1788.014 MWh. /yr. to 1533.75 MWh. /yr.