Load modelling for generating capacity reliability evaluation using the frequency and duration method

This method makes it possible to determine all major reliability indices: probability and frequency of system deficiency states and the expected energy not supplied to the consumers. Simple two-level daily load models have been suggested. The higher load level is taken to match with the estimated daily load peak and the lower level is usually assumed to be equal to mean value for different days. To investigate the applicability of two-level load models for assessing generation system reliability for planning purposes, a series of comparative analyses of the IEEE Reliability Test System has been performed, applying the exact and various two-level load models. The applicability of two-level models in estimating the absolute and relative system reliability indices is analysed for various generation system structures and load diagram shapes. It has been shown that the two-level load approximation offers a very good estimation of the relative values of all main reliability indices