Low Frequency Oscillation Suppression of Vehicle-Network Coupling Voltage in High Speed Railway Based on Onboard Energy Storage Equipment

Abstract

The low frequency oscillation phenomenon in the coupling system of numerous electric locomotives and traction network leads to traction blockage and abnormal operation. In this paper, a new low frequency oscillation suppression method based on on-board energy storage device is proposed. First, the equivalent model of the electric locomotive-traction network coupling cascade is established. The critical conditions of low frequency oscillation are analyzed by impedance ratio criterion and Bode diagram. Then, power compensation control strategy (PCCS) is used to control the energy storage system. The equivalent model of electric locomotive-traction network coup-ling cascade with an energy storage system was established, and the stability of the cascade system was analyzed by impedance ratio criterion. The simulation results verify that the electric loco-motive with an energy storage system (ES) based on PCCS can suppress the low frequency oscillation of multiple electric locomotive-traction network coupling systems. Compared with the traditional PI controller, this method can increase the steady-state and dynamic performance of the system, including reducing fluctuation, response time and increasing the gain margin of DC voltage.