Study On Power Supply Technology Of Urban Rail AC Traction Power Supply System

The urban rail transit AC traction power supply technology is a kind of AC traction power supply mode based on 35 kV cable with a relatively high contact network voltage level.It can be used in subways and light rails to avoid the harm caused by stray currents in existing DC traction power supply systems.Eliminating stray current protection,in addition to the use of power frequency single-phase AC traction power supply technology,the contact voltage rating is relatively high,making the entire system's power supply capacity has been improved,while regenerative braking power can also be directly and efficiently used.Urban rail traction power supply technology provides new and better choices for the development of urban rail transit in the future.This paper conducts further theoretical calculation and simulation research on the urban traction AC traction power supply technology.First of all,this paper introduces the structure and composition of the urban rail AC traction power supply system in detail.The key issue of the voltage level of the contact network of the urban rail AC traction power supply system is not yet clear.Take the design conditions of the urban rail transit power supply system as a precondition,and fully consider Determining the main factors of the voltage level of the contact network,the theory of the voltage level of the contact network from 2.0 kV to 6.0 kV is made from four aspects: the composition of the catenary,the potential of the rail,the applicability of the voltage loss calculation method of the traction power supply system,and the voltage level of the traction network during the peak working condition.Calculate and analyze the voltage level of the contact network that should be selected for the traction power supply system of the urban rail.Secondly,this paper studied the parameter matrix and model of the 35 k V armored cable in detail,introduced the parameter matrix and model of the traction network,and constructed the simulation model of the urban rail AC traction power supply system based on MATLAB/Simulink.Subsequently,based on the simulation model,the distribution of load currents in the traction power supply system for urban rail transit was studied.For rail transit AC traction power supply system,the rail potential is too high,and the inhibitory effects of different rail potential limits are simulated and analyzed,and the rail potential suppression scheme is determined.Simulate and analyze the sensitivity change of the main influencing factors of the capacitance effect of the 35 kV armored cable;simulate and study the single arm maximum power supply distance of the single main substation power supply scheme,and verify the superior performance of the urban rail AC traction power supply technology in the power supply capacity.Finally,the AC traction power supply scheme was designed based on the actual line conditions of a city rail 2nd line.The scheme was divided into a single main substation power supply scheme and a two main substation power supply scheme.In order not to lose the generality,each design proposal considers the case where the short-circuit capacity requires a phase compensation device.The technical scheme of the main substation and the layout of the traction substation are explained in detail.The peak operating condition was the traction network voltage level,and then the single main substation power supply scheme and the two main substation power supply schemes were analyzed and compared.