Reliability Analysis of Switch Placement in Radial Distribution Network Considering Failure Probability

Abstract

A comprehensive reliability assessment of radial distribution networks (RDN) by examining the operational impact and failure probability of protective devices such as isolators, fuses, and remote-controlled switches (RCS). The study starts with analytical evaluation of the 4-bus RDN and demonstrates the absence of protection causes complete feeder outages for any interruption. Reliability is significantly improved when fuses and isolators are added, as they enable selective isolation and faster service restoration. The work further investigates the practical scenario in which protective devices may fail, and results show notable deterioration in reliability indices when considering switch failure probability. To address this, a genetic algorithm (GA)-based optimization model is proposed for the optimal placement of isolators and RCS while explicitly incorporating their failure rates. The proposed method aims to minimize total system cost, including investment and customer interruption cost. The proposed method is tested on a modified IEEE 34-bus network confirms that 17 protective devices provide the optimal trade-off between economic investment, interruption reduction, and overall system reliability, whereas additional devices offer negligible improvement. The findings highlight the critical importance of incorporating realistic switch reliability during planning, ensuring accurate estimation of network performance and enhancing distribution system resilience.