Research on Stability of Multi-Parallel Inverters with Different Control Methods in Islanded Microgrid

摘要

Aiming at the stability problem of multi-parallel inverters for various distributed generators (DGs) in the islanded microgrid, firstly, the system model of parallel inverters is established and the system is equivalent to a dual-input single-output system, and Nyquist criterion is used to judge its stability. Unstable reason of parallel inverters with different control methods is further analyzed. Then, the impedance of voltage-controlled inverter is reconstructed to solve the resonance problem for the parallel inverters, and a strategy of the virtual harmonic negative impedance at the resonance frequency is proposed. Finally, the simulation results verify the correctness of theoretical analysis and the feasibility of the proposed strategy.