Abstract
Due to the attractive advantages such as modularity, scalability and excellent power quality of modular multilevel converter (MMC), converters based on MMC could be a promising alternative solution for traction transformer. A novel MMC-based advanced co-phase traction power supply system is proposed in this paper to solve power quality issues and eliminate the neutral sections in the traditional traction power supply system. And in the proposed system, a DC power transmission system is designed, which provides convenient access for distributed energies benefiting the utilization of the natural resources such as solar energy and wind energy along railways. In order to ensure the normal operation of the proposed system, nearest-level modulation considering voltage balancing is designed for MMCs. The mathematic model three-phase MMC-based rectifier is derived in detail. Based on the mathematic model, dual current-loop control is designed for the rectifier. Besides, the parallel operating traction substations suffer circulating current issue. A droop control combining with double closed-loop control is designed to deal with the problem. The correctness and feasibility of the system and its modulation and control strategies is verified through simulation and a small-scale experiment.
Highlights
The traditional traction power supply system that adopts a step-down transformer to feed two strictly isolated feeders is widely used in AC electrified railway system [1]–[5]
The main contribution of this paper is that a novel modular multilevel converter (MMC)-based advanced co-phase traction power supply system with a DC-bus is proposed, the control and modulation strategies are designed to ensure the normal operation of the proposed system
Since a large number of SMs are series-connected in the proposed MMC-based advanced co-phase traction power supply system, Nearest-level modulation (NLM) is adopted in this paper
Summary
The traditional traction power supply system that adopts a step-down transformer to feed two strictly isolated feeders is widely used in AC electrified railway system [1]–[5]. MMC-based co-phase traction power supply system is presented in [3], where the APC is implemented by using a three-phase MMC In these applications, only power quality issues can be solved, the neutral sections still remain. The main contribution of this paper is that a novel MMC-based advanced co-phase traction power supply system with a DC-bus is proposed, the control and modulation strategies are designed to ensure the normal operation of the proposed system. In the proposed MMC-based advanced co-phase traction power supply system, neutral sections can be completely eliminated and power quality issues can be thoroughly solved, and a port for the convenient access of distributed energies such as solar energy, wind energy, and energy storage system is reserved.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
