Short-Term Reliability Assessment for Islanded Microgrid Based on Time-Varying Probability Ordered Tree Screening Algorithm

As the penetration rate of intermittent renewable energy continues to increase in a microgrid, the operational model of interconnected microgrid changes faster and more frequently. To maintain the stability and security of the microgrid, short-term reliability assessment is necessary and must be adapted to the time-varying characteristics of the islanded microgrid. In view of this, this paper proposes a new short-term reliability assessment method based on the time-varying probability ordered tree screening algorithm. First, a screening algorithm based on the time-varying probability ordered tree is proposed, and the number of system states is reduced by screening the system state with high probability at each time. Then, according to the different impact ranges, two event types of load point power supply interruption is defined, and the formulas are given for calculating the time-varying probability. On this basis, the loss of load probability (LOLP) index and the expected demand not supplied (EDNS) index are defined to assess the short-term reliability of the islanded microgrid. Finally, the proposed method is modeled by MATLAB, and a case study is performed on the European low-voltage microgrid system to verify its correctness and effectiveness.