大型接地网性能评价技术综述

Review on Performance Evaluation Technology for Large Grounding Grid

综述了发电厂、变电站(换流站)大型接地网性能评价技术的现状和存在问题,介绍了大型接地网多维度评价的理念、最大暂态入地电流计算方法、安全性指标,以及地电位升、接地阻抗、网内电位差、跨步电位差和接触电位差校核方法,指出应摒弃传统只强调接地阻抗单一指标的不科学评价模式。介绍雷电冲击下大型接地网暂态散流和电位分布特性以及雷电下的均压优化要求,以及大型接地网多维度评价技术在接地网运维阶段和设计阶段的应用,并探讨接地降阻技术、接地阻抗准确测量技术、接地网腐蚀诊断技术和防腐技术等。最后对大型接地网技术的研究热点进行了展望。

This paper summarizes current situation and existing problems of performance evaluation technologies for the large grounding grid of the power plant, the substation or the converter station. It introduces ideas of multidimensional assessment, the calculation method for the maximum transient earth current, safety indices, and verification methods for ground potential rise, grounding impedance, ground potential difference, step potential difference and touch potential difference. It points out the traditional unsicientific evaluation mode for performance evaluation that only emphasizes on the single index of grounding impedance should be abandoned. Meanwhile, it introduces transient current divergence of the large grounding grid and distribution characteristic of the potential under lightening surge as well as requirement for voltage-sharing optimization. It also introduces application of the multidimensional assessment technology for the large grounding grid in operation maintenance stage of the grounding grid and the design stage, and discusses technologies such as resistance reduction technology, accurate measurement technology for grounding impedance, diagnosis technology for corrosion of the grounding grid and anti-corrosion technology. Finally, it outlooks research hotspots of large grounding grid technologies.