张北柔性直流电网故障电流特性及抑制方法研究
Research on the Fault Current Characteristic and Suppression Strategy of Zhangbei Project
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摘要: 张北柔性直流电网示范工程为确保换流阀在直流故障情况下可靠穿越,在直流线路配置150m H电抗器、中性线配置300m H电抗器,电抗器限制故障电流发展速度的同时也降低了故障电流衰减速度,导致极端故障情况下换流阀保护晶闸管的结温超出设备耐受水平。该文研究张北工程故障电流衰减机理,针对设备耐受能力和故障耐受要求不匹配问题,提出3种解决方案,并通过PSCAD/EMTDC仿真对3种方案的技术性能进行分析验证,通过ANYSYS仿真软件对不同技术方案换流阀晶闸管结温进行校核,验证技术方案的可行性。最后综合对比不同技术方案的优缺点,为张北工程建设提供技术支撑。Abstract: In order to make sure DC fault ride through, Zhangbei 500 kV four-terminal VSC-based DC grid demonstration project configures 150 mH reactors in the DC line and 300 mH reactors in the neutral line. The reactors not only limit fault current developing speed, but also damping speed. This paper studied fault current damping problem of Zhangbei project in the extreme cases, fault current damping mechanism and tolerance requirement for converter valve were analyzed. According to the problem of mismatching between converter tolerance ability and tolerance requirement, three kinds of solutions were proposed. Each scheme’s technical characteristics were analyzed and verified with PSCAD/EMTDC. Thyristors junction temperature of converter valve was calculated by ANYSYS, which verified the effectiveness of proposed solutions. At last, a comprehensive comparison was conducted, pointing out the advantages and disadvantages, which support for the construction of Zhangbei project.
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