New Configuration of Multifunctional Dynamic Voltage Restorer with Renewable Energy Integration for Performance Improvement

Aiming at improving the voltage-based power quality issues and maximizing the utilization of renewable generation (RG) simultaneously, this paper proposes a microgrid multifunctional dynamic voltage restorer (MFDVR). Whether the grid voltage disturbances (such as sag, swell) happen or not, the MFDVR can always work by adopting vector control. Based on it, MFDVR realizes the full utilization of RG when the normal grid voltage happens, and it can utilize RG along with ensuring the stability for the voltage of critical loads during grid voltage disturbances, both of which expand the function of device. In addition, the constraint problem between output power and output voltage of the inverter can be solved by adding a series coupling capacitor in structure. This method, which can apparently reduce the output voltage of inverter combining the multifunctional method mentioned above, thereby reduce the voltage demand of DC side and the voltage stress of switch. All of those broaden the operating range and improve the performance of device effectively. The operating principle of the proposed MFDVR, power flow under different conditions and the optimization mechanism of the coupling capacitor are analyzed in detail. Simulation results verify the effectiveness of the proposed topology and control strategy.