A New Half-Bridge Winding Compensation-Based Power Conditioning System for Electric Railway with LQRI

Facing the challenges brought by the negative sequence current (NSC) pollution in power supply system of electric railway, a new topology named half-bridge winding compensation-based railway power conditioner (HBWCRPC) without auxiliary step-down transformer is proposed to suppress the NSC injected into the public networks. It has the advantages of high integration, low losses, and more functions. The compensation principle is discussed, and its physical interpretation is presented. Besides, the mechanism of the voltage perturbation and its various representations in steady state are analyzed. Considering the complexity of voltage perturbation, an optimal control method is adopted to improve the robustness of the control system, and a linear quadratic regulator with integral action, which is applicable for this system, is designed. Finally, simulation and experiment results validate the HBWCRPC system and its control method.