Due to the access of overhead ground wires of different voltage level transmission lines,the topology structure of the main grounding grid of substation operating with overhead ground wire will change significantly,and its grounding impedance cannot be measured by simply using the grounding impedance measurement method of power system grounding device. Moreover,it’s usually hard to unlock the overhead ground wire and measure the substation grounding impedance in operation,and the measurement will inev-itably be affected by the diversion of overhead grounding wire. In order to eliminate the influence of overhead ground wire,it is re-quired to measure the shunting current of each outlet frame connected with the overhead ground wire. In this paper,a grounding im-pedance measurement test for the main grounding grid of a substation operating with overhead ground wire is carried out,and a method of measuring the overhead ground wire shunt based on flexible Rogowski coil and frequency selective multimeter is proposed. The re-sults show that the overhead ground wire diversion ratio can reach 43.4%,and the angle between the shunt current and the class power frequency current injected into the main grounding grid as a reference is -19.5°. The grounding impedance of the main grounding grid of the substation is calculated,and the error between the calculated result and the experimental result is very small. The results demonstrate that the measurement method of grounding impedance of substation with overhead ground wire and the measurement meth-od of overhead ground wire shunting are correct.%由于不同电压等级的输电线路架空地线的接入，带架空地线运行的变电站主接地网拓扑结构发生了很大变化，其接地阻抗并不能简单照搬电力系统接地装置接地阻抗的测量方法。同时，生产运行中往往难以解开架空地线来测量变电站主接地网的接地阻抗，必然会受到架空地线分流的影响。为了剔除架空地线分流的影响，需要测量与架空地线相连的各个出线构架的分流电流。利用远离夹角法在某运行变电站开展了带架空地线的变电站主接地网接地阻抗测量试验，并基于柔性Rogowski线圈和可选频万用表，提出了一种测量架空地线分流的方法。结果表明，架空地线分流比例可以达到43.4％，且与作为参考的注入接地网的类工频电流的夹角为－19.5°。计算了该运行变电站主接地网接地阻抗，并与试验结果进行了对比，发现两者误差很小，验证了带架空地线的变电站接地网接地阻抗和架空地线分流测量方法的正确性。
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