Impact of Transmission and Subtransmission Failures on Distribution Reliability Indices

This paper presents a probabilistic approach to measure the impact of transmission and subtransmission equipment failures on the performance indices of electric distribution systems. The proposed approach includes the modeling of failures originated from the main substation equipment and transmission lines, based on Markovian models, as well as the effect of load transfers through the high and medium voltage network under contingency conditions, in order to reproduce the operational reality of the companies. The reliability indices are assessed through a non-sequential Monte Carlo simulation. The proposed methodology allows a ranking of regions with the greatest need for investments and quantifies the improvement in the reliability performance of reinforcements and operational strategies. The proposed method is applied to a large network, which is part of the Brazilian electrical system.