Uncertainty consideration in power system well-being assessment using fuzzy set approach

With increased energy demand, less new transmission, and open access, the power system is experiencing a much greater level of power transfer. These new requirements push the system to its limits for maximum economic benefit, while maintaining sufficient security margins that require network analysis. A practical interconnected system can collapse due to a number of different limits being exceeded such as thermal and operating reserve. Usually probabilistic methods are used in the conventional reliability assessment. The large amount of uncertainty is implicit in the estimate of system reliability because of insufficient failure data and variation in environmental conditions. In practice, limits are imposed by the operators on power system parameters, like line flows and bus voltages are crisps when dealing the deterministic technique, but in real, these limits are no longer of a crisp nature and are considered as soft constraints. The reliability parameters such as failure and repair rates used in the probabilistic models basically come from historical operation records, and leads to considerable data uncertainty. In this paper an approach to assess the health of the bulk power system by incorporating the fuzzy sets is suggested. To deal with the issue of large number of contingencies, a fuzzy logic based ranking of outages is also illustrated. This paper provides an approach to extend the conventional probabilistic reliability analysis by including fuzzy set for the assessment of wellbeing of a composite power system in the adequacy domain.