Multidimensional evaluation method for large-scale grounding grid

An evaluation method and the technology of grounding grid, which are applied in the direction of measuring devices, instruments, and measuring electronics, can solve the problems of measuring characteristic parameters, heavy workload, and rising potential of grounding conductors, so as to avoid systematic deviations, achieve significant benefits, and aim at strong effect

Inactive Publication Date: 2014-03-05
ELECTRIC POWER RES INST OF GUANGDONG POWER GRID +1
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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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Examples

Experimental program
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Embodiment example 2

[0129] 1. Basic situation and simulation of grounding grid topology

[0130] A 500kV substation has been in operation for 12 years. After the second-phase expansion, there are currently three 500kV main transformers with a capacity of 750MVA each. There are 13 circuits of 220kV outgoing lines, and the outgoing line structure has a total of 15 lightning protection lines (including 4 OPGW optical fiber ground wires); there is no 10kV cable outgoing line. The site of the substation is located in a hilly area. The current main grounding grid is 351.5m×289.5m without expansion; the horizontal grounding zone adopts 60mm×60mm×6mm galvanized flat steel with a total length of 19000m, and the buried depth is 0.8m. The vertical grounding electrode adopts Φ50mm, A galvanized steel pipe with a length of 2.5m (total length 450m), a total of four 30m deep wells are drilled at the edge of the ground grid and pressure-filled with a drag-reducing agent. The topological structure of the ground g...

Embodiment example 3

[0160] 1. Basic situation and simulation of grounding grid topology

[0161] A 220kV substation has been in operation for 19 years. Currently, there are two 220kV main transformers with a capacity of 150MVA each. There are a total of 5 circuits of 220kV outgoing lines. The outgoing line structure has a total of 6 lightning protection lines (including 3 OPGW optical fiber ground wires); The outlet structure has a total of 8 lightning protection wires (including 4 OPGW optical fiber ground wires); a total of 18 circuits of 10kV outlets are used as the transition from the 10kV high voltage room of the substation to the 10kV overhead outlet not far from the outer wall of the station, basically within the scope of the externally expanded grounding network , can be used as a part of the substation ground network. The substation is located in the coastal hilly area. The terrain around the substation is relatively flat and the soil conditions are average. There are fields on both side...

Embodiment example 4

[0210] 1. Basic situation and simulation of grounding grid topology

[0211]A 500kV substation has been in operation for 15 years. Currently, there are three 500kV main transformers with a capacity of 750MVA each. There are a total of 4 circuits of 500kV outgoing lines. The outgoing line structure has a total of 8 lightning protection lines (including 4 OPGW optical fiber ground wires); a total of 11 circuits of 220kV outgoing lines. There are 12 lightning protection wires in the outlet structure (including 6 OPGW optical fiber ground wires); there is no 10kV cable outlet. The site of the substation is backed by hills and facing the open coastal alluvial plain. In front of the station are fish ponds and paddy fields, and the deep soil conditions are good. The total grounding area of ​​the entire 500kV Shantou substation is 802,134m2 after considering the network expansion outside the station; the horizontal grounding zone adopts Φ22mm hot-dip galvanized round steel with a tota...

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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...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): G01R31/00
Inventor 李谦肖磊石饶章权张波
Owner ELECTRIC POWER RES INST OF GUANGDONG POWER GRID
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