Method for determining grounding resistance value of large-scale grounding system

Abstract

The invention discloses a new method for determining the grounding resistance value of a large-scale grounding system. The new method is characterized in that an apparent resistance calculating curve and an apparent ground resistance measurement curve are simulated through a computer and compared to be coincident, and the grounding resistance value when the large-scale grounding system independently exists can be accordingly and finally determined based on the earth resistivity and the grounding resistance value which are measured on site. The new method has the advantages that utilization of the method is not influenced by the local soil structure on site, and when measurement is not required to be carried out, the distance between the position of a current electrode and the grounding system must be more than 6.5 times the size of a grounding grid. In this way, based on physical conditions such as the site complex terrain structure and multiple in-and-out-line loops of power generating stations and transformer substations, nondestructive measurement on the grounding resistance of the large-scale grounding system can be carried out, and the measurement and calculation accuracy is improved.

Description

technical field [0001] The invention relates to a method for determining the grounding impedance value of a large-scale grounding system, which belongs to the field of electric system safety evaluation. Background technique [0002] According to the requirements of national and electric power industry standards, after the substation is put into operation, the grounding resistance value of its grounding system needs to be measured regularly to understand the changes in its safety performance. Most of the existing measurement methods use the 0.618 method, but this measurement method is based on the following assumptions: the field soil is uniform soil, the grounding system is small in size and can be considered as hemispherical, and the current electrode is far enough away from the grounding system during measurement (more than 6.5 times ground grid size). However, in actual operation, the local soil structure is mostly inhomogeneous, and there are a large number of overhead ...

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Problems solved by technology

However, in actual operation, the local soil structure is mostly inhomogeneous, and there are a large number of overhead ground wires and structures around the grounding system, which do not meet the requirements of the existing measurement methods, thus greatly affecting the measurement results of grounding resistance, and cannot be obtained. Reliable ground resistance value

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