数字电流选跳在地铁中压环网供电保护的应用
张目然
Application of Digital Current Selective Tripping Protection in Subway Medium Voltage Ring Network Power Supply
ZHANG Muran
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作者信息:广州地铁集团有限公司，510030，广州
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Affiliation:Guangzhou Metro Group Co., Ltd., 510030, Guangzhou，China
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关键词:
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Key words:
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DOI:10.16037/j.1007-869x.2024.10.048
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中图分类号/CLCN:U231+.8
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栏目/Col:应用技术
摘要:
［目的］相较于传统的中压环网供电系统保护机制，数字电流选跳保护展现出了更好的速动性和选择性。然而，在选跳保护技术赋予保护范围无限扩展潜力的同时，电缆电容电流所产生的影响却日益凸显，成为不可忽视的因素。因此，需对地铁供电系统中压环网大分区下的数字电流选跳保护及整定设计进行深入研究。［方法］鉴于我国众多城市地铁供电系统已广泛采用数字电流选跳保护方案，选取广州地铁具体保护跳闸案例，通过对保护装置所记录的波形数据进行详细分析，进一步剖析故障区内与区外跳闸的根本原因。［结果及结论］故障区内的录波数据呈现出典型的单相接地故障特征，这与实际的电缆故障情况相吻合。而在故障区外，电流波形的畸变则显示是由电压的突变引起。由于地铁33kV环网的三相负载基本保持平衡，且在C相失压时，A、B相电压虽然会经历短暂的畸变(持续时间约为3个周波)，但此时间段内负载电流的变化可忽略不计。因此，三相电流的畸变主要由电缆的电容电流导致，针对此情况，数字电流选跳保护的整定设计原则应适时进行完善。
Abstracts:
［Objective］ Compared with traditional protection mechanism of medium-voltage ring network in power supply system, digital current selective tripping protection has quicker motion performance and better selectivity. However, while providing the possibility of infinite extension of protection range by selective tripping, the impact of cable capacitance current gets prominent and becomes a factor that cannot be ignored. Therefore, it is necessary to conduct in-depth research on digital current selective tripping protection and its setting design under the large partition of medium voltage network in subway power supply system. ［Method］ In view of the fact that digital current selective tripping protection is widely adopted by many urban rail power supply systems in China, a specific protection tripping case of Guangzhou Metro is selected to analyze in detail the waveform data recorded by the protection device, and further analyze the root causes of tripping phenomena in and out the fault zone. ［Result & Conclusion］ The wave recording data in the fault zone exhibits typical single-phase grounding fault characteristics, which is consistent with the actual cable fault situation. However, outside the fault zone, the distortion of the current waveform is shown to be caused by the sudden change of voltage. Due to the basic balance of the three-phase load in subway 33 kV ring network, and in the case of phase C voltage loss, although the voltage of phases A and B experiences a brief distortion (about 3 cycles), the change in load current during this period can be ignored. Therefore, the distortion of the three-phase current is mainly caused by the capacitance current of the cable. In view of this situation, the setting design principle of the digital current selective tripping protection should be improved in a timely manner.
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