| With the rapid development of China’s railway industry,the operating mileage of high-speed railways is increasing and the running speed is increasing continuously,at the same time,it also brings greater energy consumption demand.According to statistics,the national railway energy consumption conversion standard coal reached 151,258,000 tons in2022.The energy consumption of traction power supply system has become more and more serious after several large speed-up of electrified railways.Therefore,reducing energy consumption of electrified railways will help to achieve "low-carbon transportation".When an electric locomotive is running on a long slope section of a high-speed railway,the traction load has the characteristics of strong impact,fast changing frequency and large gap between peaks and valleys.As a result,the traction transformer takes the load demand as its installation capacity.The traction transformer has a high instantaneous load rate and a low average full-day load rate,which results in a large amount of electricity costs and seriously affects the economy of the system.At the same time,in the long slope section of high-speed railway,a large amount of regenerative braking energy produced by electric locomotives can only be used for a small part,and the remaining energy returned to the public grid will cause waste.Therefore,the capacity of high-speed railway long slope traction transformer is optimized to reduce the installation capacity of traction transformer and increase the utilization rate of regenerative braking energy by introducing storage energy in coordination with railway 10 k V distribution system(hereinafter referred to as 10 k V system).This has important practical significance for high-speed rail energy-saving operation and improving system economy.This thesis takes the long slope of high-speed railway as the background to optimize the capacity of traction transformer.The regenerative braking energy is stored and utilized by the combined configuration of hybrid storage energy and 10 k V system,which can reduce the installation capacity of traction transformer and improve the system economy.Firstly,This thesis describes the research status of different types of transformer capacity optimization and energy storage technology in traction power supply system,and summarizes the different structures,advantages and disadvantages of AC Traction Power Supply Systems(AC-TPSS)with energy storage.On this basis,the overall structure of AC-TPSS is determined,and the energy flow mechanism,power distribution and operating conditions of the system are analyzed.Based on the power distribution strategy,the measured data of traction load on high-speed railway are processed to provide basic data for the optimal capacity configuration of traction transformer.Then,considering the storage and utilization of regenerative braking energy by Supercapacitor storage system,an optimal capacity configuration model of traction transformer is established,and PSO and LWOA algorithms are used to optimize the capacity of traction transformer.Finally,considering the combination of hybrid storage energy and10 k V system,the AC-TPSS structure is provided for the connection of hybrid storage energy and 10 k V system.Through formulating the matching power allocation strategy,a traction transformer capacity optimization model for 10 k V system is established,which aims at the lowest system equivalent annual cost.The LWOA algorithm is used to optimize the capacity of traction transformer,and then the single supercapacitor storage energy is obtained.Comparing and analyzing the results of capacity optimization of mixed storage capacity with10 k V system.The capacity optimization configuration model of traction transformer with single Supercapacitor storage,combined storage with 10 k V system is established and compared in MATLAB platform.The optimization algorithm is used to compare the two schemes with those without optimization.The two schemes reduce the economic cost by 5.8% and 10.7%,respectively.The economic cost of hybrid energy storage and 10 k V system is reduced by5.2% compared with single supercapacitor energy storage,which verifies the effectiveness of the traction transformer capacity optimization configuration method. |
