Abstract
This paper describes a new practical methodology for studies on required generating capacity in powergeneration planning. In the process of evaluating electricity supply reliability, actual data of various changingfactors, such as demand variation due to the daily ambient temperature changes, reduction in capacity due to the forced outage of generating units and load forecast errors, are statistically treated and represented as probability distribution. In addition, this methodology takes into consideration other factors like the maintenance schedule of generating units and emergency operating measures in case of capacity shortage. They are practically important but they have rarely been handled so far. Examples of study results using the proposed methodology in the power system of Tokyo Electric Power Company are also presented.
