An Improved Droop Control Strategy for VSC-Based MVDC Traction Power Supply System

Due to the development of advanced power electronic techniques, voltage-source-converter-based medium voltage dc (MVDC) traction power supply system (VSC-based MVDC TPSS) could be an alternative supply solution for high-speed railways (HSRs) in the future. The distributed configuration of the MVDC system, along with dynamic load and catenary resistance, makes the control of such system a real challenge. In this paper, an improved droop control method is proposed to obtain a better performance of system operation for the specific supply environment without any communication links. The proposed control scheme can eliminate the voltage deviation due to droop action and improve catenary network voltage control dynamics by using voltage-shifting and load current feedforward control approaches simultaneously. Additionally, the detailed model of the proposed control scheme is derived and the stability in the case of moving load is critically tested. Finally, a simulation model based on MATLAB/Simulink and an experimental prototype have been established to validate the effectiveness of the proposed control method.