I. Introduction
THREE-phase stand-alone inverters are generally employed in distributed generation (DG) based systems that are located in remote regions with limited access to the grid and regions experiencing frequent uncertainties in grid operation. In a typical grid-connected configuration, the inverters are operated in current control mode or direct power control mode. In this case, the requirement for voltage control does not arise as the deviations in voltage are suppressed by the presence of the grid which can be considered as a stiff voltage source. However, in the absence of a grid, the micro-grids are prone to deviations in voltages and frequencies that are fed to the loads. These fluctuations when exceeding acceptable limits cause undesirable power quality issues that have degrading and damaging effects on the associated domestic, industrial, and commercial loads. Hence, there is a requirement for a stable voltage and frequency control scheme to ensure the safety of these loads.