Characteristic analysis of three-phase four-leg inverter based load unbalance compensator for stand-alone microgrid

This paper analyses a three-phase four-leg voltage sourced inverter (VSI) based load unbalance compensator (LUC) including its control algorithm, which is a component of a microgrid. The purpose of proposed three-phase four-leg VSI based LUC is to improve power quality of the stand-alone microgrid. Power quality of the microgrid which was installed in Mara-island, Korea is analysed using a real operational data. In this work, the microgrid in Mara-island which includes a photovoltaic power generation system, a diesel generator, a battery energy storage system, and a power management system is modelled in PSCAD/EMTDC, and proposed three-phase four-leg VSI based LUC is also modelled and applies to the microgrid. Power flow and stability of the modelled microgrid with the LUC is analysed under variable irradiance and unbalance loads. The results show that the proposed LUC helps to improve stability of the stand-alone microgrid. The proposed three-phase four-leg VSI based LUC and its control algorithm can be effectively utilized to the stand alone microgrid which has large unbalance loads.