Optimal Fractional Order Control of Virtual Inertia Emulator for a Microgrid with High Renewable Energy Penetration

A microgrid with high renewable energy penetration and low inertia is vulnerable to transients in the frequency response due to the sudden mismatch of generation and demand. The virtual inertia concept is used to minimize the rate of change of frequency (RoCoF) by supplying adequate power through an energy storage device during the mismatch of load and generation. In this research, a tilt-integral-derivative (TID) controller was used to control the virtual inertia (VI) emulator in a microgrid with high renewable energy penetration comprising thermal, wind, and solar power generation units. A PEO-GA algorithm combining some salient features of the population extremal optimization (PEO) and the genetic algorithm (GA) was used to optimize the gains of the TID controller by minimizing the integral of the absolute error (IAE) criterion. The VI emulator used in this work incorporates the RoCoF as well as the proportional frequency deviation. Therefore, both transient and steady-state frequency response is improved. The proposed PEO-GA-TID control offers 72.8% and 9.6% less IAE of the frequency response than the GA-PID and GA-TID controllers respectively.