交流供电制式下地铁牵引变电所地回流组成分析
李鲲鹏1刘力2赵云云1王凌霄2何竹君1曹晓斌2
Analysis of Ground Current Return Composition at Metro Traction Substations under AC Power Supply System
LI Kunpeng1LIU Li2ZHAO Yunyun1WANG Lingxiao2HE Zhujun1CAO Xiaobin2
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作者信息:1.广州地铁设计研究院股份有限公司， 510010， 广州
2.西南交通大学电气工程学院， 611756， 成都
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Affiliation:1.Guangzhou Metro Design and Research Institute Co., Ltd., 510010, Guangzhou, China
2.School of Electrical Engineering, Southwest Jiaotong University, 611756, Chengdu, China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.20245885
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中图分类号/CLCN:U231+.8
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栏目/Col:供电与能源
摘要:
［目的］为了提高城市间的通勤能力，新建市域快速轨道交通采用了27.5 kV的交流牵引供电制式，其运行时速更快。交流牵引供电在增强列车运输能力的同时，对外泄漏电流增大，出现地回流偏大等现象，需对交流供电制式的地铁线路主变电所中地回流的组成进行深入研究。［方法］以广州市某条采用交流牵引供电制式的市域快速轨道交通线路为研究对象，分析了该线同时给车站和停车场供电的牵引变电站回流系统的组成及其地回流路径。为了得到地回流电流在总回流电流中的占比关系，在线路开通前的联调联试阶段，对该牵引变电所的回流电流进行测试，对现场接线进行勘测，并进行了铜覆钢接地体电流测试。在此基础上进行了大地土壤回流电流测试，提出了地回流的改善方案。［结果及结论］主变电所地回流电流偏大的主要原因是存在铜覆钢回流电流。除当前所知的车站和停车场电缆回流、大地土壤回流外，还存在1条通过电缆沟支架的路径，有25%以上的牵引电流通过该路径流回牵引变电所的接地网，进而导致地回流电流测量结果偏大。采用改善方案后，实际通过大地土壤回流的电流占总回流的30%左右，达到地回流质量的优良水平。
Abstracts:
［Objective］ To enhance the intercity commuting capacity, newly built city rapid transit lines adopt a 27.5 kV AC (alternating current) traction power supply system, enabling higher operating speed. While improving train transport capacity, AC traction power supply also increases external leakage currents, resulting in excessive ground return currents. Therefore, it is necessary to conduct an in-depth research on ground return current composition in metro line main substations using AC power supply system. ［Method］ Focusing on a city rapid rail transit line in Guangzhou that adopts AC traction power supply system, the composition and ground return path of current return system at the traction substations that supply power to both stations and depots is studied. To determine the proportion of ground return current within the total return current, tests on return current are conducted during the joint commissioning and testing phase before the line opened. The return current of traction substation is tested, the wiring layouts are investigated on-site, and current measurements of the copper-clad steel grounding body are performed. On this basis, tests on earth soil return currents are conducted, and improvement measures for ground return are proposed. ［Result & Conclusion］ The primary reason for excessive ground return current at the main substation is the presence of return current through copper-clad steel structures. In addition to the known station and depot cable returns and earth soil returns, there exists an additional return path through cable trench supports, accounting for more than 25% of the traction current flowing back to the traction substation grounding grid via this path, thereby leading to larger results from ground return current measurements. After implementing the proposed improvement measures, the proportion of current returning through earth soil decreased to approximately 30% of the total return current, achieving an excellent level of ground return quality.
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