The Enhancement of Protective System Reliability with Immune Algorithm

This paper is to derive the optimal planning of protective relay schemes for a transmission network by immune algorithm. The historical data of protective relay malfunction in Taipower has been used to determine the failure rate and repair rate of each type of protective relays in Taipower system. The Markov models of protective relays are determined and integrated with the transmission network to solve the customer service interruption due to protection relay malfunction for each substation. According to the load composition and service interruption cost of customers served, the outage cost of each substation is calculated- The objective function of system reliability cost is then formulated by considering the customer interruption cost of all substations and the investment cost of protective relay systems. By minimizing the system reliability cost with the proposed IA algorithm, the optimal planning of protective relay system is therefore obtained to achieve the best cost effectiveness of protection relay investment