Voltage Unbalance Compensation for Islanded Microgrids with Hybrid Control Approach

Voltage unbalance is one of the challenges of low-voltage microgrids. It is often caused by unbalanced loads connected to the microgrid. Its compensation is required to ensure an efficient microgrid operation. In this paper, a voltage unbalance compensation mechanism based on modifying the control signals is explored. A hybrid control scheme is used to control and regulate the distributed generators (DGs) inverters in an islanded low voltage microgrid. The DGs inverters are either controlled as grid-forming or grid-feeding units. A voltage unbalance compensation mechanism using local measurements is used to reduce the voltage unbalance at the different points throughout the microgrid. This voltage unbalance compensation is performed only by the grid-forming controller which uses local voltage measurements only. The compatibility between the control algorithm and the compensation mechanism is shown through different test scenarios. The simulation results obtained using Matlab/SimscapePowerSystems prove the effective performance of the proposed approach.