大型接地系统接地阻抗测量的引线互感分析

接地测量引线存在互感,严重影响大型接地系统接地阻抗测量结果的准确性。首先推导了任意布线形式接地测量的互感理论模型,并基于引线互感修正项的复镜像拟合实现了模型求解。与更正的穿透深度公式的对比结果表明,复镜像法求解互感的精度较高。研究了5D-0.618法、2D-30度夹角法、90度夹角法和反向法在不同引线长度和土壤电阻率情况下的互感数值规律。结果表明:5D-0.618法和2D-30度夹角法在大型接地系统的阻抗测量时互感导致结果偏大,需要进行互感校正;反向布线法互感为负值,其互感影响程度需要结合工程实际作评估。

Analysis of Lead Mutual Inductance in Grounding Impedance Measurement of Large-Scale Grounding System

There is mutual inductance in grounding measurement leads,which seriously affects the accuracy of grounding impedance measurement of large-scale grounding system.Firstly,the mutual inductance theoretical model of ground connection measurement is derived,and the model is solved based on the complex image fitting of the modified term of the mutual inductance.The comparison with the corrected penetration depth formula shows that the complex image method is more accurate for mutual inductance.The mutual inductance numerical laws of 5D-0.618 method,2D-30 degree angle method,90 degree angle method and reverse method under different lead length and soil resistivity are studied.The results show that 5D-0.618 method and 2D-30 degree angle method need to correct mutual inductance,which is caused by mutual inductance in impedance measurement of large-scale grounding system,and negative mutual inductance in reverse wiring method,the degree of mutual inductance should be evaluated in combination with engineering practice.