发变电站防雷接地阻抗测量分析

防雷接地网作为发变电站交直流设备接地及防雷保护接地,对保障生产安全运行起着重要的作用。发变电站接地网的测量结果存在接地阻抗值超标、感性分量过大的问题。通过仿真计算和实测对接地网测试中的感性分量对比分析,结果表明:接地阻抗的感性分量随着电流引线与电压引线之间距离增大而减小,通常不会大于阻性分量。过大的感性分量是由测试引线互感引起。基于此,给出了剔除互感阻抗的测量与计算方法,为接地网阻值的科学测试提供理论依据。

Measuring of Grounding Impedance of Power Plants and Substations

As the grounding of AC and DC equipment and lightning protection equipment, grounding grids play an important role in ensuring the safety of production operation. Measurement results of several plants show that the grounding impedances are all beyond the standard values, and that the inductive component is too big. A comparative analysis between theoretical simulation and measured results of the inductive component of grounding impedance shows that inductive component, which is generally no greater than resistive component, decreases with the increasing distance between current lead and voltage lead, and that excessive inductive component is caused by mutual induction. Based on the above, a method for calculating and eliminating the mutual inductance between the lead wires is brought out, which lays a foundation for reaching the exact grounding impedance.