| Under the background of carbon neutrality and emission peak,integrating nearby renewable energy into electrified railways is becoming a trend for future development.The northwest region of China has a relatively high reserve of wind power generation,and the technology is mature,making it feasible to integrate them into traction power supply systems.However,because of the powerful unpredictability and oscillations of wind energy production and the sporadic and unstable burdens of rail vehicles,accomplishing a dynamic equilibrium between the supply and the demand will pose a considerable challenge after wind energy is incorporated into the train’s power grid.Therefore,a wind-storage system is proposed to establish a balance between generation and load.This thesis discusses the expected improvement of operational characteristics and cost-effectiveness after the wind-storage systems are integrated into traction power supply systems,serving as a reference for future applications of renewable energy integration into traction power supply systems.The thesis focuses on the capacity optimization configuration of wind-storage systems integrated into traction power supply systems,which includes the following research:Firstly,the topology and operational characteristics of the "source-load-storage" structure of traction power supply systems were analyzed.The basic working principles and mathematical models of wind power generation systems and hybrid energy storage systems based on batteries and super-capacitors were described.Based on the conventional topology of traction power supply systems and the operating characteristics of traction loads,two new types of traction power supply system with "source-load-storage" structure was constructed,and the topological structure and operational characteristics of the two "source-load-storage" structure with supply arm access and RPC access were compared and analyzed,to provide a foundation for subsequent researches.Secondly,an energy management strategy for wind-storage systems integrated into traction power supply systems was proposed.To improve the operating status of the battery and prolong its lifespan,a hybrid energy storage coordination control strategy was established,with the moving average method and VMD algorithm being used for power allocation.To avoid overcharging and over-discharging of the energy storage device,a load peak shaving and valley filling control strategy was established based on the SOC correction charge and discharge power of the energy storage device to achieve collaborative operation between energy storage devicesFinally,a capacity optimization configuration model of wind-storage systems based on the Life Cycle Cost theory was established.In this model,with the annual average equivalent cost of energy storage systems as the objective function and power balance,energy storage equipment charge and discharge power,and energy storage equipment SOC as constraints,the traditional Grey Wolf Optimizer algorithm was improved by introducing a nonlinear convergence factor and penalty function method based on the Theory of Good Point Set to avoid falling into local optima and to improve the convergence speed.The capacity optimization configuration and system operation status were analyzed through actual examples and simulation.The research results show that the integration of wind-storage systems into traction power supply systems can reduce the power fluctuation of traction substation power supply.By using the optimization model and solution algorithm proposed in this thesis,the system operating cost can be further reduced,which is beneficial to the economic operation of traction power supply systems after the integration of wind-storage systems in the future. |
