Improving Transient Stability of an Islanded Microgrid Using PV Based Virtual Synchronous Machines

Renewable energy integration is rapidly increased in this decade to achieve clean energy production targets. Inverters are commonly used to integrate renewable energy sources, such as wind and solar to the power system. Conventional power generation such as Coal, Nuclear, Hydro are based on synchronous generators. Due to the large integration of renewable power plants, the power system is moving towards an inverter dominant power system. This can make a significant impact on the system inertia response. Inertia is given from the rotating mass of the conventional generators but, inverters cannot contribute to system inertia as there are no rotating masses. Lack of inertia will weaken the stability of the system under disturbances. As a result, system frequency will fluctuate beyond its limits. This limits the integration of renewable sources to grids. However, inverters can emulate inertia response because of the fast response and the high controllability. This paper presents two novel controllers that can be used to emulate the inertia response. One controller is for the virtual inertia controlling and the other controller is for energy management. Results are obtained and analyzed in a simulated PV-Hydro microgrid under supply-demand mismatch.