Dc-bus voltage regulation and power compensation with bi-directional inverter in dc-microgrid applications

This paper presents a single-phase bi-directional inverter with dc-bus voltage regulation and power compensation in dc-microgrid applications. In dc-microgrid applications, a power distribution system requires a bi-directional inverter to control the power flow between dc bus and ac grid, and to regulate the dc bus to a certain range of voltages, in which dc load may change abruptly. This will result in high dc-bus voltage variation. In this paper, we take into account this variation and propose an on-line regulation mechanism according to the inductor current levels to balance power flow and enhance the dynamic performance. Additionally, for power compensation and islanding protection, the bi-directional inverter can shift its current commands according to the specified power factor at ac grid side. Simulated and Experimental results obtained from a 5 kW single-phase bi-directional inverter have verified the analysis and discussion.