Frequency Control Method of Isolated Micro-grid With Virtual Synchronous Generator Mode Switching

In view of the problem that the adjustment effect of the traditional PI-based frequency control method is not efficient in the asymmetric operation state of the micro-grid, a frequency control method based on the mode switching of the virtual synchronous generator (VSG) is designed. Specifically, firstly, on the frequency regulation of PI controller in the asymmetric operating state, the influence mechanism of the double fundamental frequency component is analyzed. Secondly, the mode switching method is designed to judge the operating state of the power grid by the asymmetric degree matrix. Thirdly, aiming at the asymmetric operation state, the effective control of microgrid frequency is realized by introducing integral to eliminate the double fundamental frequency component to obtain new data of active power. Finally, under asymmetric operating conditions, comparative experiments, which verifies the feasibility and effectiveness of the proposed method, show that the proposed method has more advantages in reducing frequency deviation and frequency fluctuation.