Multi-stage underfrequency load shedding for islanded microgrid with equivalent inertia constant analysis

This letter addresses a multi-stage underfrequency load shedding (UFLS) approach to restore the frequency for islanded microgrid. Depending on the magnitude estimation of power deficiency, the multi-stage UFLS approach for islanded microgrid is put forward. The proposed approach takes the load stages into consideration, which can achieve frequency restoration mainly by adjustable loads shedding and ensure uninterruptible power supply of the most important loads. Based on the established microgrid, the method to obtain the equivalent inertia constant of islanded microgrid is simulated and demonstrated. And time domain simulation results show that the proposed UFLS approach can restore the frequency stability of islanded microgrid effectively considering the multiple stages of loads.

► The existence of the total equivalent inertia constant of microgrid is proved.
► The approach to estimate the magnitude of active power deficiency is proposed.
► A multi-stage UFLS approach based on the equivalent inertia constant analysis is proposed.