Assessing the impact of substation-related outages on the network reliability

This paper presents a modern probabilistic reliability assessment method that includes the modeling of substation configurations and simulation of breaker and switching operations in response to equipment failures in the evaluation of transmission grid reliability. Such features are not generally available in conventional power flow analysis tools. The method has been applied to study two 500 kV substations in the East China power system as part of the development of along-term transmission expansion plan for the EHV power grid. The first stage of the analysis is to assess the impact of the substation layouts on transmission component outages. Reliability models for the substations, including detailed bus-breaker arrangements, are developed. Failures of substation components, such as in-coming and out-going transmission lines, transformers, bus sections, circuit breakers and disconnect switches, are represented by their respective outage statistics. A failure mode and effect analysis of each substation is then performed and reliability indices consisting of frequencies and durations of events leading to outages of multiple transmission lines are calculated. Next, the substation-related transmission line outages are input to a power flow model for assessing their impact on,the reliability of the overall grid. This paper contributes to the area of transmission planning studies using probabilistic reliability methods.