Mode Adaptive Droop Control With Virtual Output Impedances for an Inverter-Based Flexible AC Microgrid

A decentralized power control method in a single-phase flexible ac microgrid is proposed in this paper. Droop control is widely considered to be a good choice for managing the power flows between microgrid converters in a decentralized manner. In this work, to enhance the power loop dynamics, droop control combined with a derivative controller is used in islanded mode. In grid-connected mode, to strictly control the power factor in the point of common coupling (PCC), a droop method combined with an integral controller is adopted. Small-signal analysis of the proposed control is shown both in islanded and grid-connected mode. The proposed control scheme does not need any mode switching action. Thus, it is relatively simple in control for full mode of operation. Smooth transitions between the operation modes and the effectiveness of the proposed control scheme are evaluated through simulation and experimental results.

I. Introduction

By SUCCESSFULLY integrating power electronics and new emerging technologies, distributed generation (DG) has become an increasingly competitive option compared to a conventional centralized system. Among the various DG configurations available, the microgrid approach offers the most flexibility and reliability for power systems, and thus the microgrid is generally regarded as the most attractive DG system configuration [1],[2].