矿区变电站进线段杆塔辅助接地网散流特性研究

Research on stray current characteristics of auxiliary grounding grid of incoming line tower of mine substation

针对矿区变电站进线段杆塔接地网外延降阻存在地形受限、有效散流长度短、降阻效率低等问题,提出对进线段杆塔采用长距离外延引线辅助接地的降阻方法,并通过防雷接地计算软件CDEGS建立“Τ”型、“Γ”型、方框型、垂直型单向辅助接地网仿真模型,研究钢管塔单向辅助接地网的散流特性及其影响因素。研究结果表明:外延引线长度越大,降阻效率越高;在高频电流作用下,外延引线长度超过60 m时,降阻效率稳定在80%左右;“Γ”型单向辅助接地网散流特性稳定,分流能力强,降阻效果最好;在不同土壤条件下,单向辅助接地网降阻效率在70%以上。在实际工程应用中,建议根据实际土壤条件确定辅助接地网的外延引线长度与终端结构,将辅助接地网铺设至土壤电阻率较小区域或对土壤电阻率较大区域采取局部换土措施,以提高进线段杆塔单向辅助接地网的降阻效率。

In view of problems of limited terrain,short effective dispersion length,and low resistance reduction efficiency in the extensional resistance reduction of the grounding grid of incoming line section of mine substation,a resistance reduction method using long-distance extension lead for auxiliary grounding of incoming line tower was proposed.The grounding calculation software CDEGS is used to establish simulation model of"Τ"type,"Γ"type,box type,vertical type unidirectional auxiliary grounding network,and study stray current characteristics of unidirectional auxiliary grounding grid of steel tube tower and corresponding influencing factors.The research results show that the longer the extension lead,the higher the resistance reduction efficiency;when the extension lead length exceeds 60 m,the resistance reduction efficiency is stable at about 80%under the action of high-frequency current;the"Γ"type unidirectional auxiliary grounding grid has stable stray current characteristics,strong shunting ability,and its resistance reduction effect is the best;resistance reduction efficiency of the unidirectional auxiliary grounding grid is more than 70%under different soil conditions.In practical engineering applications,it is recommended to determine the extension lead length and terminal structure of the auxiliary grounding grid according to the actual soil conditions,and to lay the auxiliary grounding grid to areas with low soil resistivity or to take local soil replacement measures for areas with high soil resistivity to improve the resistance reduction efficiency of unidirectional auxiliary grounding grid of the incoming line tower.