Fuzzy probability and power system safety

The paper proposes a fuzzy event-tree analysis of electric power protection system reliability. The elaborated analysis proposes a new algorithm used for fuzzy event-tree calculation. On this purpose a fuzzy logic system (FLS) was elaborated. The proposed SLF has got, as an output element, the electric-power protection system "Safety" instead of the usually "Risk" parameter, used in engineering applications (with, or without fuzzy logic elements). In the paper the FLS output is used for independent analyzing of an electric power protection system. But it is elaborated for a complex analysis including the power system connected with its protection system. An efficient software toll FETA ("Fuzzy Event-Tree Analysis"), for independent analyzing of an electric power protection system "Safety", was built. It is able to compute "General Safety" fuzzy conclusion about the analyzed system and also the General Safety Degree index.