利用架空线路测量接地装置接地电阻的误差研究

笔者分析了利用架空线路作为电流、电压线测量接地网接地电阻的误差来源,指出了线路的架空地线未与地绝缘是产生测量误差的根本原因。通过建立数学模型研究了变电站接地电阻值、电流回路电阻值、杆塔接地电阻值、架空地线类型的改变对接地电阻测量误差的影响;指出接地装置对地电压测量偏差主要受架空地线的短接范围的影响。为了减小大电流法测量接地装置接地电阻的误差,应当令测试范围内架空地线对地绝缘或采取人工放线的方式。

Error Sources of Grounding Grid Resistance Measurement Using Overhead Ground Line

The authors analyze error sources of grounding grid resistance measurement making use of overhead ground line as current or voltage wire,and find the principal source is due to the overhead ground line uninsulated with earth.Therefore,a mathematical mode is established to investigate the effects of substation grounding resistance,current loop resistance,tower grounding resistance,and type of overhead ground line on the measurement error of grounding grid resistance.It is concluded that the ground voltage measurement error of the grounding grid is mainly affected by short range of the overhead ground line.In order to reduce the measurement error of grounding grid resistance by large-current method,overhead ground line ought to be insulated with earth within test scope or a manual wire-release way be taken.