Fuzzy logic and probability based real time contingency ranking

A combined fuzzy logic and probability based approach is suggested for ranking of contingencies for power system real time steady-state security evaluation. A contingency is ranked, by taking into account the probability of occurrence, the severity of caused violation of system voltage and thermal rating limits and the amount of curtailed load. The impacts are also evaluated by the number of buses, network branches and load points unfavorably affected by contingencies. All the aforementioned impact types are measured by associated membership grades to the sets of heavy impacts built based upon the past experience of the system operators.