Implementation of a virtual inertia control for inertia enhancement of a DC microgrid under both grid connected and isolated operation

In this paper, a virtual inertia control-based unified control technique is proposed for the DC bus voltage control unit of a DC microgrid to regulate the DC bus voltage and emulate inertia. In addition, a restoration control is also used in cascade with the virtual inertia control to reduce the steady state error in the DC bus voltage. The DC bus voltage control unit consists of a bidirectional DC-DC converter and a bidirectional grid connected inverter. Further, a feedforward controller is designed for the DC bus voltage control loop to improve the dynamic performance. A small-signal model of the DC bus voltage control unit is developed to analyse the dynamic performance and to design the parameters of the virtual inertia controller. Finally, the effectiveness of the proposed technique is tested under both grid connected and isolated operation of the DC microgrid considering the variation of both sources and loads. The simulation results reveal the successful control of the DC bus voltage during transient and steady state conditions.