为提高变电站接地网腐蚀诊断的效率和精度，提出一种新的诊断方法。基于有限元方法，计算激励电流在地表激发的磁感应强度，通过仿真计算，分析土壤结构对地表磁感应强度的影响；通过接地网的两下引导体直接注入和抽出异频的正弦波激励电流，基于电磁感应原理测量地表磁感应强度分布，诊断网格导体腐蚀变细和断点故障；结合变电站实际的电磁干扰环境，设计磁感应强度测量系统。实验和现场检测结果表明所提方法简便、有效，诊断系统满足测试需要，可用于工程实际。

A new diagnosis method on corrosion of grounding grids is put forward in order to improve the efficiency and precision of diagnosis. The surface magnetic induction intensities excited by the injected current were computed and the influences of the soil structures were analyzed based on the finite element method (FEM). A sine wave exciting current of different power frequency was injected directly into grounding grid by two ground lead wires. At the same time, the distributions of the surface magnetic induction intensities were measured based on the electromagnetic induction theorem, then the corrosion states of mesh conductor becoming thin or broken can be diagnosed. Combining the practical electromagnetic interference (EMI) enviroment in substation, a system of measuring magnetic indution intensity was designed. Experimental and practical results show that the method proposed is simple and effective, the system satisfy the testing needs and can be used in engineering practice.

国家自然科学基金项目(50577019)；国家杰出青年科学基金项目(50325723)；河北省自然科学基金项目(E2006000678)。