Presentation of an Economical Centralized Combinational Load Shedding Scheme for Self-healing of Power System

In recent years, several catastrophic power blackouts have occurred worldwide. The blackout has become a common concern in many power systems. To prevent widespread blackouts, various load shedding schemes have been suggested in the literature. Among these schemes, combinational voltage-frequency load shedding schemes have better technical performance against severe and combinational events, since in such events the voltage stability and frequency stability of the system are usually jeopardized simultaneously. On the other hand, the cost-effectiveness is one of the most important performance measures of any industrial scheme. Therefore, in this paper an adaptive combinational centralized load shedding algorithm is proposed for self-healing of the power systems in which the economic cost of load shedding and the amount of load shed power are minimized while the voltage and frequency stability of the system are kept. In this algorithm, two criteria are developed for selection of appropriate loads for load shedding based on the combination of the online voltage stability indices of busbars and the load prices. The simulation results obtained for the standard New England 39-bus test system show that the proposed algorithm reduces the economical cost of the load shedding and improves the steady state system frequency as well as the voltage stability margin of the buses compared to the previously proposed load shedding methods.