Multidimensional evaluation method for large-scale grounding grid

Abstract

A multidimensional evaluation method for a large-scale grounding grid includes the following steps of on-site testing, numerical calculation based on the electromagnetic field principle and multidimensional evaluation on the grounding grid. The foothold of the multidimensional evaluation method for the grounding grid is based on basic functions of the grounding grid, the basic functions are stream breaking and potential holding safety performance under power frequency grounding faults and lightning stroke faults, and the evaluation problems of characteristic parameters reflecting the safety performance of the grounding grid under the power frequency grounding faults and in the state of lightning stroke are mainly solved, wherein the characteristic parameters relate to grounding grid potential rising, potential difference in the grid, a step voltage, a contact voltage and the like. The multidimensional evaluation on the grounding grid is achieved from the aspects of the characteristic parameters of the grounding grid, integrity of the grounding grid, corrosion evaluation, thermal stability check and the like, safety of the grounding grid is expressed more scientifically, the evaluation on the state of the grounding grid is more accurate, and the safety problem and the defects of the grounding grid are rectified more effectively in a more pertinent mode.

Description

technical field [0001] The invention relates to a multi-dimensional evaluation method for large-scale grounding grids in the electric power industry, specifically referring to large-scale grounding grids (hereinafter referred to as "grounding grids") of 200MW and above power plants or 35kV and above substations (including converter stations and high-resistance stations) ) safety evaluation method. Background technique [0002] The basic function of the grounding network is not only to provide a common reference ground for various electrical equipment in power plants and substations, but more importantly, it can quickly discharge fault current or lightning current when the system has a ground fault or lightning intrusion, and improve the grounding system. The role of the grid metal conductor and the potential distribution of the ground surface in the field ensures the safety of the next and secondary equipment and personnel in the fault state. The grounding grid is an import...

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Problems solved by technology

[0008] The multi-dimensional evaluation of the grounding grid is mainly based on the basic function of the grounding grid, that is, when the equipment grounding short circuit fault occurs in the substation site, the fault current is quickly discharged and the ground potential distribution of the substation is improved. As the grounding grid has the characteristics of a concealed project, for the safety evaluation of the entire grounding grid, the complete measurement of the above-mentioned characteristic parameters cannot be realized by simply using the on-site measurement method, and the workload is too large. On the other hand, the measurement and evaluation of the above characteristic parameters is a rather complicated work, which is affected by many factors such as the size and shape of the grounding body itself, the structure of the outlet grid, and the uniformity of the soil around the site. no breakthrough

[0009] With the development of computer technology, the numerical analysis method based on the principle of electromagnetic field can realize the accurate simulation of the characteristics of the grounding grid, and can consider the influence of complex factors on site, make up for the inherent defects and deficiencies in the site measurement, and can solve: a) with overhead It is difficult to accurately measure the grounding impedance of the outgoing ground wire and the ground grid of the 10kV cable sheath; b) The potential rise distribution of the grounding conductor and the field pressure difference cannot be measured on site, and thus it is impossible to judge the high potential external introduction and the impact on the secondary system ; c) The problem of test blindness caused by the difficulty in finding the edge of the ground grid and the high-level step voltage area in the actual measurement of the step voltage; d) The problem of the blindness of the test caused by the difficulty of complete measurement in the actual measurement of the contact voltage

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