Stability and adaptability analysis of the traction power supply system with photovoltaic and energy storage under two access structures

The integration of photovoltaic and the energy storage system into traction power supply systems under railway power conditioner (RPC) or voltage source converter (VSC) access structures changes the original pure AC system into a hybrid AC/DC system. At the same time, which access structure of photovoltaic and the energy storage system has higher system stability and which has better adaptability are rarely mentioned in the stability analysis of traction power supply systems with photovoltaic and the energy storage system. Firstly, in this paper, impedance models for the two types of access structures of photovoltaic and energy storage systems are established, and the port impedance characteristics and stability influencing factors are analyzed from the aspects of system parameters and controller parameters. Second, combining the two typical working conditions of PV and the ESS access traction power system, from the perspective of stability, the robustness of the two access structures under the influence of negative impedance characteristics and the adaptability of access are compared. Compared to traditional stability analysis methods, the GMPM (Gain Margin and Phase Margin) criterion employed in this paper integrates both the dynamic characteristics and frequency response of the system, making it particularly suitable for small-signal stability analysis. Keeping the rest of the conditions the same under two typical working conditions, the RPC access structure has higher system stability when the two access structures input and output 35kWof active power, respectively. Finally, the simulation results in the MATLAB/Simulink simulation platform also confirm the better adaptability of the RPC access structure.