Effects and analysis of suppressing frequency fluctuations in microgrids using virtual synchronous generator control

When a greatly varying load is connected to a weak system, stability of the system becomes a problem. In these days, because the use of renewable energy is accelerating, not only the loads but also the distributed power sources can be critical factors in destabilizing the system. The virtual synchronous generator (VSG) control allows a static inverter to behave similar to a synchronous generator (SG). Using this VSG technology, we can decrease the introduction ratio of SGs with fossil fuels, and thus, we can combine various types of power sources. At the same time, if the combination of governor and rotor inertia is represented in a first-order lag element, the VSG can suppress the frequency fluctuations in microgrids. In this paper, we present a design guideline of a VSG. The simulation results by EMTP-RV confirmed that the parallel-connected VSG can suppress the frequency fluctuation. In addition, the results were almost consistent with the experimental test results.