Virtual inertia control of PV systems for dynamic performance and damping enhancement of DC microgrids with constant power loads

DC bus voltage in islanded DC microgrids (MGs) is prone to power fluctuations of sources and loads. This is due to the lack of generational inertia, which is caused by high penetration of converter-based renewable energy sources (RESs). With the growing penetration of RESs, especially photovoltaic arrays (PVAs), they are required to provide grid support services such as inertial response in a similar way to conventional synchronous generators. Here, a virtual inertia control (VIC) is proposed for PVAs to enhance the inertia of a hybrid PVA-battery DC MG. The proposed VIC employs active power control of PVAs to provide virtual inertial response (VIR) without using any high-power energy storage system such as supercapacitors. An adaptive virtual inertia gain is introduced to achieve dynamic power sharing between the PVAs that provide VIR. Impedance-base stability analysis is utilised to study the impact of the virtual inertia gain on the system stability and to show the impact of the proposed VIC on improving the stability margin of the DC MG in the presence of destabilising constant power loads (CPLs). Finally, simulation results are presented to verify the effectiveness of the proposed method in dynamic performance and damping enhancement of the DC MG and reducing the high-current stress on the battery.