中性点灵活接地技术在桐乡电网20 kV改造中的应用

Application of Neutral Point Flexible Grounding Technology in 20 kV Transformation of Tongxiang Power Grid

首先对桐乡地区进行20kV改造后出现的20kV馈线高跳闸率进行分析,明晰配网中性点以单一经小电阻接地是问题所在;其次从国内外研究现状出发,借鉴10kV层面混合接地的相关思路,提出在20kV层面开展灵活接地的设想,确立技术原理、划设工作流程;再次结合桐乡电网实际运行工况,就20kV灵活接地的实现进行一、二次设计和定值整定,重点对与消弧线圈并接的小电阻的投切回路作了双重化配置,以及小电阻投入失败的应急补救设计;最后以2个变电所实际运行数据为依托,分析了灵活接地的投运功效。

Firstly, the high tripping rate of 20 kV feeder line after 20 kV reconstruction in Tongxiang area is analyzed, and it is clear that the reason is that the neutral point of distribution network is grounded by a single small resistance. Then, based on the research status home and abroad, the idea of developing flexible grounding at 20 kV level is proposed based on the relevant ideas of 10 kV hybrid grounding, with the technical principle and working flow being set up. Combined with the actual operating conditions of Tongxiang power grid, the first and second circuit design and setting of 20 kV flexible grounding are carried out, with emphasis on the dual configuration of the switching circuit of small resistance parallel to the arc suppression coil, and the remedial design of the failure of small resistance switching in emergency. Finally, based on the actual operation data of two substations, the commissioning effect of the flexible grounding was analyzed.