Power system reliability evaluation considering substation interior under protection failure impact

In order to measure the impact of substation interior on power system reliability under protection influence, a hierarchical power system which consists of equipment level, substation level and power system level is established. A stratified-sampling Monte-Carlo method is proposed based on Markov state space and functional decomposition. Probabilities of substation equipment states are calculated with Markov Models. Functional decomposition is done according to the result of relay protection. The expected accident set of station is formed with the minimum cut set algorithm based on adjacency matrix. Substation equipments and protection functional groups are sampled respectively. The off outlet and inlet lines are recognized through comparing the expected accident set with the sample fault set. After that, reliability index can be figured out. The result certifies that the above-mentioned method can assess substation interior and power system as a whole and do quantitative analysis of the influence of substation equipments and substation structures with protection failure on power system reliability.