A Novel Topology for Voltage Sag Mitigation Utilizing Solid-State Transfer Switches and Power Conversion System

Voltage sag is one of the most frequent issues affecting power quality, can lead to abnormal operation of equipment, resulting in significant economic losses. This paper proposes a novel topology for voltage sag mitigation utilizing the solid-static transfer switch (SSTS) and power conversion system (PCS), and the operational principles are analyzed thoroughly. Under normal grid conditions, the PCS operates in grid-connected mode, supporting the grid in peak shaving and valley filling. Upon the detection of a voltage sag in the grid, the SSTS promptly activates, and the PCS switches to off-grid mode to ensure the continuous and reliable supply of power to the loads. A dual closed-loop control structure is devised to optimize both the dynamic and steady state performance of the PCS, with the inner-loop employing state feedback control, and the outer-loop employing a proportional-integral (PI) controller. The effectiveness of the proposed topology for voltage sag mitigation and the superior performance of the employed control structure for PCS are validated through MATLAB/Simulink.