With the increase of the proportion of new energy power generation and the low inertia characteristics of the external power grid, the traditional traction power supply system lacks effective inertia response ability, which leads to the frequency stability challenge of the traction power supply system. In view of the above problems, this paper proposes an energy storage based virtual synchronous generator railway power conditioner (ES-VSG-RPC) control strategy. Firstly, the basic principle of ES-RPC dynamic compensation of negative sequence current and harmonic current is analyzed, and the current compensation control strategy is studied. Then, according to the load power and frequency of the left and right power supply arms, a system frequency considering load weight is proposed, and the traction power supply system is equivalent to a single-area power supply system. Then, by combining the swing equation of synchronous generator and the power equation of super capacitor, the active power of energy storage device is controlled by system frequency, and the inertia response process of synchronous generator is simulated. A DC-DC control strategy of ES-VSG is proposed. Finally, the time domain simulation model is built in MATLAB/Simulink to verify the effectiveness of ES-VSG-RPC control strategy under typical working conditions of traction power supply system. The results show that in the low inertia traction power supply system, ES-VSG-RPC can not only ensure the dynamic compensation of power quality, but also dynamically control the charging and discharging power of energy storage, improve the frequency stability of traction network and support its dynamic operation.