| 引用本文: | 盛诗意,徐习东,李 峰,等.双极柔性直流系统阀交流侧接地保护研究[J].电力系统保护与控制,2026,54(03):99-108. |
| SHENG Shiyi,XU Xidong,LI Feng,et al.Study on grounding protection of the valve AC side in bipolar VSC-HVDC systems[J].Power System Protection and Control,2026,54(03):99-108 |
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| 摘要: |
| 针对双极柔性高压直流系统阀交流侧接地故障产生的故障电流无过零点的问题，分析了故障端换流器闭锁后故障端和非故障端故障电流的特征，推导了解析表达式，得到了非故障端判断对侧接地故障的判据及保护方案。由于反向穿越零点的电弧电流有利于交流断路器弧隙介质绝缘能力的恢复，分析了故障后降低直流电压对阀交流侧故障电流反向穿越零点的影响，提出了非故障端退出运行后故障端直流侧非接地极经电阻接地的保护方案，推导了限流电阻与阀交流侧故障电流的表达式。最后在PSCAD/EMTDC平台上进行了仿真计算，结果表明，通过非接地极经电阻接地的方式不仅可以使换流变压器阀侧故障电流反向穿越零点，还可以避免换流变压器出现三相短路的情况。 |
| 关键词: 双极柔性直流输电 模块化多电平换流器 接地故障 偏向于时间轴一侧的故障电流 继电保护 |
| DOI：10.19783/j.cnki.pspc.250500 |
| 分类号: |
| 基金项目:国家自然科学基金重大项目资助(62293500)；南方电网公司科技项目资助(GDKJXM20231022) |
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| Study on grounding protection of the valve AC side in bipolar VSC-HVDC systems |
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SHENG Shiyi1, XU Xidong1, LI Feng2, CHEN Danqing2, LUO Shuxin2
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1. College of Electrical Engineering, Zhejiang University, Hangzhou 310000, China; 2. Power Grid Planning and
Research Center, Guangdong Power Grid Co., Ltd., Guangzhou 510623, China
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| Abstract: |
| To address the issue that fault currents caused by grounding faults on the valve AC side of bipolar VSC-HVDC systems have no natural zero-crossing points, the characteristics of fault currents at both the faulty and healthy terminals after converter blocking at the faulty end are analyzed. Analytical expressions are derived, and a criterion and corresponding protection scheme for the healthy terminal to identify grounding faults on the opposite side are obtained. Since arc currents that reverse and pass through a zero crossing are beneficial for restoring the dielectric strength of the arc gap in AC circuit breakers, the impact of reducing DC voltage after a fault on the reverse zero-crossing behavior of valve AC-side fault currents is investigated. Based on this, a protection scheme is proposed in which, after the healthy terminal is taken out of operation, the non-grounded pole on the DC side of the faulty terminal is grounded through a resistor. The expressions for the current limiting resistor and the valve AC-side fault currents are derived. Finally, simulations are performed on the PSCAD/EMTDC platform. The results demonstrate that grounding the non-grounded pole through a resistor can not only enable reverse zero-crossing of valve-side fault current of the converter transformer, but also effectively prevent the occurrence of three-phase short circuits in the converter transformer. |
| Key words: bipolar VSC-HVDC modular multilevel converter grounding fault fault current biased to one side of the time axis relay protection |
