A new passive islanding detection approach considering the dynamic behavior of load in microgrid

In this paper, a new passive detection approach is proposed to solve the islanding problem of microgrid which consists of synchronous and inverter-based distributed generators. The test system for islanding detection is introduced first, and then derivative of the equivalent resistance with respect to time for test system is utilized as the islanding detection index. Under the islanding condition, the index approaches zero. However, the result of grid-connected condition is opposite. In addition, most of islanding detection methods focus on the steady-state behavior of parallel RLC load where the active power of load is directly proportional to the square of voltage. However, in fact, the active power of load would vary with change in voltage and grid frequency, which also significantly impacts islanding detection. Therefore, a new passive islanding detection method considering the dynamic behavior of load is proposed, at the same time, the threshold is obtained. The performance of proposed method has been studied in comparison with other passive islanding detection methods. Simulation results verify that the proposed method has good reliability under islanding and system disturbance conditions.