Virtual Inertia Based Inverters for Frequency Mitigation By Incorporating VIC and Multi-Power Level Controller In Grid Connected Renewable Energy

Abstract

The penetration of Renewable Energy Sources (RESs) into microgrids is gaining huge significance in recent times. RESs are integrated with conventional grid systems to meet the growing energy demand and to enhance the power quality. The increasing penetration of RES into the grid system affects the stability of frequency in microgrids due to the stochastic nature of photovoltaic (PV) and wind energy generation. Unlike in traditional power generation systems, the lack of rotational inertia in microgrids is one of the critical concerns which affects the integration of RES with the grid system through power electronic converters. This introduces more uncertainties into the system and hence the operation and control of such a system becomes more complicated. In order to maintain the stability of microgrids and to effectively utilize RESs and distributed generation (DG) systems, it is essential to control virtual inertia. Proper inertia control improves the flexibility of microgrid operation and as a result various controlling strategies have been proposed in the past to control the virtual inertia. This paper presents a new virtual inertia control (VIC) approach with a multi power level controller (MPLC) for RES integrated microgrids. Considering the high level penetration of RES, the proposed approach is designed to enhance the system performance under sudden load variations and frequency variations. The efficiency of the proposed control approach is validated with and without MPLC. Results show that the controller achieves better frequency stability with MPLC.