The impact of protection systems on power system reliability

Abstract

This report is a collection of memos written to describe the methodology for quantifying the impact of protection systems on power system reliability. Including the effect of protection system response scenarios on a transmission system is vital for a realistic appraisal of the reliability attributes of electricity supply. This is usually accomplished by resorting to Markov models. As a viable alternative, a new procedure based on approximate methods of system reliability evaluation is proposed in this work. This is used in conjunction with the OPAL methodology for reliability analysis of power systems. The overall reliability model is thus based on minimal cutsets for each delivery point, which are obtained from an analytical contingency enumeration approach. The results are first demonstrated on the four bus OPAL test network. Additional dependent failure considerations in the modeling are then illustrated on a Modified OPAL (MOPAL) test network. Further, the impact of substation configuration arrangement (breaker-and-a-half scheme) has been investigated, on the transmission protection system failure dependency propagation and the consequent effect on reliability of supply. The results are presented for the MOPAL test network.