杆塔分流对大型接地网接地阻抗测量的影响分析

针对与发电厂、运行变电站接地网相连的架空避雷线、电力电缆外护套分流电流导致的接地网接地阻抗测量误差问题,提出了利用杆塔分流测量技术精确测量接地网阻抗的方法,即向接地网注入异频测试电流,由在测量点的测量设备主机实时采样、记录测试电流幅值和相角,将测试电流波形信号在测量区域无线发射。同时,在变电站出线各构架基脚处接收该信号,用柔性罗氏线圈测量各构架基脚所流过的异频电流的模值和相角,进而确定分流电流值并计算分流电流和,在测试电流中去除该分流电流和,准确计算出接地网的实际电流值及接地网接地阻抗值。该方法可提高大型接地网接地特性参数测试的准确性。

Study of Tower Shunt Current Effect on Accurate Measurement of Grounding Impedance

Aimed at the problem that the ground impedance measuring existed deviation due to the shunt current of overhead ground wires and power cables＇ outer sheath connected with the power plants or substations, proposed a measuring method based on wireless transmission principle. Firstly, the amplitude and phase of the different-frequency test current were recorded at the measuring point in real time as a reference waveform signal, and the current waveform was transmitted to the field outlet structure wirelessly. These signals were collected at the structure foots, from where the phase difference of current was measured using flexible Rogowski coils. Then, the shunt vector was subtracted from the tested current vector to acquire actual injecting current through grounding network, in which way could improve the test accuracy of large grounding characteristic parameters.