Research On Transient Circuit Model For Integrated Grounding System Of High-Speed Railway

Due to the growing surge of railway transport supply and demand, high-speed railway in China was developing rapidly in recent years. However, the distribution of China’s railway is very wide, geographical, climatic conditions and other conditions of areas have large differences, so lightning accidents often happens. Integrated grounding system can provide discharge channel for the lightning current. So it is very important to research lightning impulse transient circuit model of the high-speed railway roadbed section integrated grounding system.The research what is known is only limited in impulse response of separate grounding, ground networks and circuit model of integrated grounding system under normal operating conditions. When lightning current getting through integrated grounding system, circuit model of integrated grounding system and impulse response don’t have a clear research results. In terms of the power system, many scholars are researching transient characteristics of grounding system, but as a subsystem of high-speed rail system which is protecting high-speed rail system, integrated grounding system exists huge differences with grounding grid of the power system.This paper identified transient circuit model according to the characteristics of Integrated grounding system. Firstly, it segmented the conductors, and made length l and lateral dimensions of each segment of the wire are much smaller than the wavelength of the electromagnetic wave, which is considered delayed effects can be ignored on the conductor, the conductors meet electromagnetic quasi-static field assumptions by segmenting. So steady-state calculation method can be used to calculate the transient circuit model. Secondly, it established lightning impulse transient circuit model of the high-speed railway roadbed section’s integrated grounding system. According to the average potential method and the image method, it put forward a method to calculate the coupling parameters between the conductor on the ground and conductor underground, and calculated the capacitive coupling and resistive coupling parameters between conductors. Thirdly, We injected lightning current into the PW line, compared the calculation results of CDEGS with results of circuit model by examining the voltage on the adjacent railway and the connecting ground wire, verified the correctness and feasibility of the circuit model. At last, Using the calculation results of circuit model, the paper set up circuit model in both cases under consideration coupling and coupling is not considered in PSCAD, separately investigated the voltage and current on the adjacent railway and the connecting ground wire in both cases coupling is considered and coupling is not considered, told out the differences when injecting lightning current in both cases. The proposed method which combined average potential method and image method can be used to calculate the coupling parameters of two long straight conductors in different medium. The circuit model we established is simple and feasible, is research foundation of lightning impulse response of the high-speed railway roadbed section’s integrated grounding system.