Energy Management Strategies for Traction Power Systems with Pv and Energy Storage Access

In recent years, in order to achieve the carbon peaking and carbon neutral goal of electrified railway, a number of railroad energy optimization initiatives have been put into practice and achieve certain results, however, energy consumption optimization alone cures the symptoms rather than the root causes. In order to cure the carbon emission problem of the electrified railway, it is necessary to realize the energy saving and emission reduction of the electrified railroad and the efficient use of new energy from both the source and the terminal of the whole life cycle of its electric energy. Therefore, under the premise of ensuring the stable operation of the system, the energy management strategy of the traction power supply system was proposed based on the concept of the smart grid, taking into account the access of photovoltaic and energy storage. Based on the operation principle of traditional traction power supply system, built a traction power supply system with PV and energy storage access, and designed a corresponding energy management strategy for it, which was divided into three layers: day-ahead regulation, intra-day regulation and real-time control. Day-ahead regulation reduced the system power purchase cost by comparing the external grid and photovoltaic tariffs in the power market over time and choosing the low price to purchase power directly, and used energy storage devices to recover braking energy, stored electricity at low tariffs and released it at high tariffs to siphon off profits. Through the shared energy storage mode, the PV and traction side energy storage devices were combined into one, reducing the idle rate of the energy storage devices and the construction costs of the system. Intra-day regulation analyzed the static voltage stability and three-phase voltage unbalance of the system based on the planned power output of each "source", and adjusted the power output of each "source" to optimize the system performance. Real-time control was based on intra-day regulation with fine-grained regulation as quickly as 1 s, by switching and combining the system working modes, the system energy supply structure was changed and the system operating conditions were quickly adjusted. And an emergency power supply plan was formulated to ensure the stable operation of the locomotive in case of an accident in the external network power supply. Through hierarchical optimization, the relatively independent barriers of each source were broken and multi-energy complementarity was realized. The following conclusions can be drawn from the cases study: (1) The system is used during the day-ahead regulation to purchase energy through the power market's power bidding time-sharing, and the shared energy storage device is used to reduce system construction costs and effectively improve the economic efficiency of system operation. (2) Through intra-day regulation, the system solves the problem of static voltage stability degradation and three-phase voltage unbalance overload caused by photoelectric access to the system, and improves system operation stability. (3) The system quickly adjusts the power output status of each "source" end of the system through real-time control, and can provide emergency energy for locomotives in case of system power supply accidents, improving system operation safety. © 2024 China Machine Press. All rights reserved.