Frequency and duration method for reliability evaluation of large-scale hydrothermal generating systems

The authors present a general frequency and duration (F&D) method that is especially adequate for predominantly hydro generating systems. The method is based on the property that not only the probabilities of reserve states can be evaluated recursively by discrete convolution but also their frequencies. Therefore, appropriate truncation and rounding techniques can be introduced allowing an efficient computation of frequency and duration indices for large-scale generating systems. The performance of the proposed F&D algorithm is analysed with two test systems. The IEEE Reliability Test System is used to measure the impact of the truncation and rounding techniques. The characteristic behaviour of frequency and duration indices in hydro systems is illustrated by a case study with the Brazilian South/Southeastern generating system