变电站空心管接地网降阻的研究与设计

Design and Study of Piping Grounding Network in Substation

以110 kV户内变电站为例,设计一种空心管接地网,通过自动监控补充水分,避免高土壤地区变电站接地网的接地电阻反弹现象。经筛选,具有良好导电性和耐蚀性的紫铜可作为接地网空心管的首选;根据短路热稳定和材料年腐蚀速度因素,应选择-50 mm×5 mm扁紫铜或准20 mm×5 mm的紫铜管,后者较前者单重减少5.8%,外表面积增大14.18%,接地效果更佳。经分析,碳酸氢钠作为一种强电介质,既起到降阻作用,又可延缓紫铜和钢材的化学腐蚀以及电腐蚀速率。经化学试验,紫铜在含氧气的过饱和碳酸氢钠溶液里会发生原电池反应,因此,配制碳酸氢钠溶液的水应为蒸馏水或无氧水。

As an example of 110 kV indoor substation, a hollow pipe type grounding network is designed, in which the amount of water can be monitored and added automatically so as to avoid high grounding resistance of the grounding network of the substation in high soil resistivity region. The pipe is made of red copper due to its good conductivity and anti-corrosion. The size is 50 mmx5 mm or （h20 mm x5 mm for rectangular or pipe respectively based on short time withstand current capability and the annual corrosion rate. Investigation shows the pipe type has better grounding effect than the rectangular type because it is 5.8% lighter in weight and 14.18% larger in surface area. NaHCO3,a strength dielectric material,may reduce ground resistance,delay chemical corrosion and electric chemical corrosion rate of copper pipe and steel. Through chemical testing, copper may generate primary cell in NaHCO3 suoersaturated solution with oxygen.so the lirmirt of NaHCO3 solution should be distilled water.