Research on Coordinated Control Strategy of Energy Storage Type Railway Power Conditioner

In order to improve the power quality of high-speed railway traction power supply system and enhance the robust stability of railway power conditioner (RPC), a coordinated control strategy based on the energy storage system (ESS) integrated RPC (ESS-RPC) is proposed in this article. It is found that the dc impedance characteristics of the back-to-back system are different when the parameters of the ESS-RPC system are perturbed under conventional control, which will affect the dc voltage of the back-to-back system and then affect the power quality of the traction system. In this article, it is analyzed that the stability difference of the bidirectional power flow of ESS-RPC under parameter perturbation is due to the negative impedance of the dc terminal and the right shift of the dominant pole. After the analysis, a coordinated control strategy of ESS-RPC is proposed to solve this problem. The small-signal analysis of the ESS-RPC system under conventional control and coordinated control is carried out, respectively, and the robust stability of the two control strategies is judged by the Nyquist stability criterion. Simulation and experimental verification are carried out in the MATLAB/Simulink environment and semisimulation platform (Modeling Tech) to analyze the impact of the proposed coordinated control strategy on the power quality of the traction power supply system and verify the effectiveness and accuracy of this coordinated control strategy.