Adaptive virtual inertia control of distributed generator for dynamic frequency support in microgrid

The distributed generator based on power electronic converters has no inherent inertial response like that from the rotating mass of the conventional synchronous generator. The control scheme of Virtual Synchronous Generator (VSG) is anticipated to improve the distributed generator system stability by imitating the behavior of the synchronous generator including the system inertia. Unlike a real synchronous generator, the equivalent inertia of the distributed generator using VSG can be controlled in a wide range with the system frequency variation. In order to explore this feature for providing a fast and smooth inertial response, a flexible virtual synchronous generator control (FVSG) strategy with adaptive inertia is proposed. By fully considering the relationship between system inertia and frequency fluctuation rate, a calculation method adopting a function of the frequency change rate to achieve an adaptive inertia coefficient is presented and introduced to the VSG control. A simulation system using Matlab/Simulink is implemented to validate the proposed FVSG control strategy on improving the system dynamic frequency performances.