Currently, there are many factors affecting the rail potential and stray current, but the influence of the superposition of the depot and the mainline on the distribution and diffusion of stray current is not considered. Considering the complex operation conditions of multiple trains in the depot and main line, the distribution characteristics of stray current and its diffusion in the ground were studied. The return system and the stray current diffusion model were jointly simulated. The layered model based on the precise integration principal component weighted iteration method can dynamically evaluate the dynamic stray current in a certain period, reduce the calculation cost, and obtain high-precision and efficient calculation results. The return system was equivalently replaced by distributed parameters and concentrated parameters, and the node voltage method is used for power supply calculation. The distribution of the rail potential and stray current leakage across the line is obtained. Considering the layered soil medium, the model of the stray current potential distribution in the ground along the mainline superimposed by the power supply at the section points was established. Based on the ground potential distribution model of the point current source in layered medium, the dynamic change model of the ground potential gradient with time was obtained.
It is important to transform the ill-conditioned problem into a benign problem that is easy to solve for the problem of solving the ill-conditioned matrix of Green's function. The weight of the principal component weighting was determined by the weighting factor q and the weighting matrix P. Different weights were superimposed on each principal component to better reduce the number of conditions. A precise integration principal component weighted iteration method for the layered model was proposed, which can solve Green's function of the layered model with high accuracy and efficiency. The validity of the layered model of stray current potential distribution in the ground was verified by physical experiments and the average error between the field results and calculated results is within 6.98%.
Combined with the engineering case of the actual line in China, comparing the field measured and calculated rail potential and ground potential gradient distribution process, the relative error range between the field measured and calculated results is within 8.46%, which shows that the model is effective. The influence of different connection modes between the mainline and the depot on the DC interference propagation process was discussed. The rail in the depot is directly grounded, and the one-way conduction device becomes the bridge connecting the depot and the mainline. The maximum current flowing into the mainline in the throat area reaches 106.62 A and the minimum current flowing into the main line reaches -330.28 A when the one-way conduction device was put into operation. The maximum surface potential gradient mode at 6.52 km away from the depot is 6.77 mV/m, and the degree of stray current is serious. Under the condition of removing the diode branch and thyristor branch fuses of the one-way conduction device, the upstream single conduction current flowing into the mainline was significantly reduced, and the maximum ground potential gradient modulus is 3.62 mV/m, which is 46.53% less than that under the operating condition of the one-way conduction device.
刘炜, 周林杰, 唐宇宁, 潘哲, 尹乙臣. 直流牵引供电回流系统与杂散电流扩散的联合仿真模型[J]. 电工技术学报, 0, (): 20235403-20235403.
Liu Wei, Zhou Linjie, Tang Yuning, Pan Zhe, Yin Yichen. Co-simulated Model of DC Traction Power Supply Return System and Stray Current Diffusion. Transactions of China Electrotechnical Society, 0, (): 20235403-20235403.
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