A Hierarchical Control Approach for Voltage Unbalance Compensation in A Droop–Controlled Micro-Grid

The smart grid and micro-grid technologies are playing necessary role in power system due to their benefi ts over traditional utility grid system. In micro grid, control and management has many functions to keep up stability and to boost power quality of the system. In this paper, a hierarchical control is presented which incorporates primary, secondary and tertiary control levels are planned for micro-grids. The primary control level consists of DG’s local controllers. Every DG local controller contains active/reactive power droop controllers, voltage and current controllers, virtual impedance loop. The secondary control level is intended to manage the compensation of voltage unbalance at PCC in an islanded micro-grid. Voltage unbalance compensation is achieved by sending proper control signals to the DG’s local controllers from secondary controller. This can be achieved by proper control of distributed generators(DG’s)interface converters. The design procedure of the system for compensating the voltage unbalance is mentioned thoroughly and also the simulation is done by using MATLAB/SIMULINK.