Optimum load shedding strategies in distribution systems

This paper investigates the impact of load shedding strategies on distribution system reliability cost indices, due to capacity deficiency conditions caused by unscheduled outages in the bulk-generation and transmission (G&T)-system. First, an integrated adequacy evaluation, including generation, transmission and distribution, is performed in order to provide detailed information on the interruptions experienced by the distribution customers. The G&T system is represented by a fictitious equivalent network, whose parameters are obtained by Monte Carlo nonsequential simulation. The equivalent G&T network is then connected with the distribution network and analyzed using minimal cut-set theory. The next step is the assessment of the reliability performance of the distribution system considering different load shedding priorities among feeders. The best strategy should account not only for the interruption costs but also for the traditional distribution indices (e.g. SAIFI, CAIDI etc.) imposed to the companies by the regulatory legislation. The proposed methodology is applied to a hybrid system created from two standard test systems. The results and their potential applications in the new power system competitive environment are discussed