特高压直流接地极入地电流对高速铁路综合接地系统腐蚀影响研究

Corrosion Impact of Ground Current of HVDC Earth Electrode on Comprehensive Grounding System of High-speed Railway System

直流输电系统以大地为回路运行时,在地中形成的电流场会对邻近多点分散接地的高速铁路综合接地系统产生电化学腐蚀影响。在介绍直流电阻与直流接地电阻仿真计算方法的基础上,针对高速铁路路基段、桥梁段、Ⅱ级和Ⅴ级围岩隧道段4种典型综合接地场景,分析其中存在的直流通路,提取出适用于长距离高速铁路综合接地系统仿真建模的“Π”形等效电路直流参数;基于此,以单位长度的泄漏电流密度为指标,比较不同高铁工程段综合接地的电化学腐蚀差异;研究接地极工作方式,土壤电阻率,接地极-高速铁路间距对高速铁路综合接地电化学腐蚀的影响规律。结果表明,当接地极阴极工作或邻近线路为桥梁区段时,高铁综合接地系统电化学腐蚀更严重,其严重程度与土壤电阻率正相关,与接地极-高速铁路间距负相关。

During the operation of HVDC system with the earth as the loop,the current field formed in the ground will have corrosion effect on the adjacent high-speed railway comprehensive grounding system.On the basis of the analysis about the calculation of DC resistance and DC grounding resistance,the existing DC circuits are analyzed for four typical comprehensive grounding scenarios of high-speed railway,i.e.bridge,track,class Ⅱ tunnel and class Ⅴ tunnel,and the"Π"equivalent circuit DC parameters suitable for long-distance high-speed railway comprehensive grounding system simulation are extracted.Based on the leakage current density per unit length,the differences between electrochemical corrosion of comprehensive grounding in different high-speed engineering sections are compared.Further,the effects of ground electrode operation mode,soil resistance and spacing of ground pole and high speed railway on corrosion of high-speed railway are studied.The results show that when the ground cathode works or the adjacent line is a bridge section,the corrosion of the high-speed integrated grounding system is more serious,and its severity is positively correlated with the soil resistance.The distance between the ground pole and the high-speed railway is negatively correlated.