Reliability Evaluation of Active Distribution Systems Including Microgrids

This paper proposes a new method for reliability evaluation of active distribution systems with multiple microgrids based on a Monte Carlo simulation. Multi-state models are developed on the basis of generalized capacity outage tables (GCOTs) to better represent various types of distributed generators in reliability evaluation. Then, the virtual power plant (VPP) is introduced to model microgrids with intermittent sources. Furthermore, the reliability behavior of VPP is efficiently characterized by an equivalent GCOT. The nonsequential Monte Carlo method is then adopted to evaluate the reliability of active distribution systems considering different operation modes under single or multiple contingencies. Some techniques—such as two-step state sampling, zone partitioning and minimal path search—are proposed to facilitate the state evaluation process and improve the Monte Carlo simulation speed. The effectiveness and efficiency of the proposed method are validated through extensive numerical tests on an IEEE test system and a real-life active distribution network.