舟山多端柔性直流输电工程换流站绝缘配合

Research on Insulation Coordination for Converter Stations of Zhoushan Multi-Terminal VSC-HVDC Transmission Project

换流站的绝缘配合是柔性直流输电工程实施的关键技术之一,其研究对换流站设备设计、选型、制造和试验具有重要的指导作用。为合理确定舟山多端柔性直流输电工程各换流站设备的绝缘水平,提出了换流站的避雷器布置方案,计算确定了相应避雷器参数及保护水平,给出了换流站设备推荐的绝缘裕度,并根据选取的设备绝缘裕度最终确定了换流站各设备的绝缘水平。文章给出了3种不同避雷器布置方案下的绝缘配合结果,结果表明不同避雷器布置主要对桥臂电抗器端子间的绝缘水平有较大影响,方案1下桥臂电抗器端子间的雷电冲击绝缘水平和操作冲击绝缘水平分别为450 kV和325 kV;方案2和方案3的避雷器布置下,桥臂电抗器端子间的绝缘水平相同,雷电冲击绝缘水平和操作冲击绝缘水平分别为750kV和550kV。除桥臂电抗器外,3种方案下换流站其他设备推荐的绝缘水平均相同,换流站联结变压器阀侧交流设备的雷电冲击绝缘水平和操作冲击绝缘水平取为650 kV(或750 kV)和550 kV,桥臂电抗器阀侧交流设备的雷电和操作冲击绝缘水平与联结变阀侧设备取为一致,换流站200 kV直流母线的雷电冲击绝缘水平和操作冲击绝缘水平建议取为650 kV(或750 kV)和550 kV,直流平波电抗器端子间的雷电冲击绝缘水平和操作冲击绝缘水平取为850kV(或950kV)和750kV。此外,文章还分析了3种避雷器布置方案的优缺点。研究结果可为该工程的建设提供重要依据,也可为其他相关工程提供参考。

The insulation coordination for converter station is one of the key technologies to implement flexible DC power transmission projects, and the results of the research on this field can provide important guidance to the design, type selection, manufacture and test of converter equipments in converter stations. To decide insulation levels for equipments of converter stations in Zhoushan multi-terminal flexible DC power transmission project reasonably, the arrester layout schemes for converter stations are proposed; corresponding arrester parameters and protection levels are calculated; the recommended insulation margins for equipments in converter stations are given and based on the selected equipment insulation margins the insulation levels for equipments in converter stations are finally determined. Insulation coordination results corresponding to three different arrester layout schemes are given and the coordination results show that different arrester layout schemes mainly influence on the insulation levels among terminals of reactors connected to bridge arms： for the first arrester layout scheme, the insulation levels of lightning impulse and that of switching impulse among reactor terminals connected to bridge arms are 450 kV and 325 kV respectively, and for the second and the third arrester layout schemes the insulation levels among reactor terminals connected to bridge arms are the same and the insulation level of lightning impulse and that of switching impulse are 750 kV and 550 kV respectively. Except reactors connected to bridge arms, the recommended insulation levels for other equipments in converter stations under all arrester layout schemes are the same; for AC equipments at valve side of converter transformer the impulse are recommended as insulation level of switching insulation levels of lightning 650 kV （or 750 kV） and the impulse is recommended as550 kV; the insulation level of lightning impulse and that of switching impulse for AC equipments at valve side of bridge arm reactors are taken the same as these for equipments at valve side of converter transformer; the insulation levels of lightning impulse of 200 kV DC buses in converter stations are recommended as 650 kV （or 750 kV） and that of switching impulse is recommended as 550 kV; the insulation levels of lightning impulse and these of switching impulse among terminals of DC smoothing reactors are taken as 850 kV （or 950 kV） and 750 kV respectively. Besides, the advantages and disadvantages of the three arrester layout schemes are analyzed. Results of this research topic can offer important foundation for Zhoushan multi-terminal flexible DC power transmission project and are available for reference to other VSC-HVDC projects.