Power quality optimization for droop-based voltage source inverters in microgrids

Recently, microgrids are receiving an increasing interest with the development of the distributed generation (DG). The droop control is often adopted in voltage source inverters (VSI) to realize the power control and sharing in microgrids. However, voltage and frequency derivations are inevitable due to the employment of the droop control, which degrades the output power quality of the VSIs. This paper focuses on improving the output current quality of the DG units by optimizing the conventional current droop control without additional sensors or devices. The virtual impedance in the control scheme is optimized to improve the low frequency distortion induced by the non-ideal feature of the devices and the dead-time effect. Furthermore, good dynamic performance of the output current is achieved by adding the current forward control into the system control. Therefore, better output quality can be with the presented control method in microgrids.