避雷线分流对杆塔接地电阻测量的影响

采用电流-电压三极法测量架空线路杆塔的工频接地电阻时，架空避雷线对注入杆塔地网的测量电流具有分流作用，从而影响接地电阻的测量精度。建立了架空避雷线对注入杆塔地网的测量电流的分流模型，分析了避雷线分流的程度和影响分流效果的因素及其影响规律。结果表明：（1）避雷线分流所占比重可以达到60%以上，当测量杆塔接地电阻较大、非测量杆塔接地电阻较小、测量杆塔为变电站出线上的前2座杆塔时，避雷线分流效果更明显；（2）仅考虑分流电流大小对杆塔接地电阻测量的影响是不够的，忽略分流电流与测量电流的相角差同样会造成较大的测量误差，导致接地电阻的测量值偏高。

Influence of Ground Wire Shunting on Tower Grounding Resistance Measurement

When using the method of current-voltage three-electrode method to measure the power frequency grounding resistance of overhead line tower, the ground wire has a role in separating the measuring current into the tower grounding grid, which can affect the measurement accuracy of grounding resistance. This paper establishes a shunting model of measuring current into the tower grounding grid for overhead ground wire, and analyzes the degree of the ground wire shunting, the factors affecting the shunting effect and its influence law. The results show that： （1）the share of the ground wire shunting can reach more than 60%； the effect of shunting is more obvious when the grounding resistance of the measurement tower is greater, the grounding resistance of the non-measurement tower is smaller and the measurement tower is the first two tower from the substation； （2）only considering the effect of shunt size on grounding resistance measurement is not enough, ignoring the phase angle difference between the ground wire shunting and the measuring current can also cause big errors, which will make the measuring value of the grounding resistance higher.