Evaluation method of transformer substation grounding grids
A technology of substation grounding grid and grounding grid, which is applied in the direction of measuring devices, instruments, scientific instruments, etc., can solve problems such as performance failure, small grounding down-conductor cross-section, poor grounding body connection, etc., and achieve high accuracy and smooth calculation process clear effect
Active Publication Date: 2015-04-29
STATE GRID CORP OF CHINA +1
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Problems solved by technology
The reason is that the grounding grid is a hidden facility buried deep underground in the power system. The main technical problems exposed on site are corrosion of the grounding grid, small cross-section of the grounding down-conductor, and poor connection between grounding bodies. These problems are caused by power failures. Hidden danger
The corrosion of the ground grid is a gradual process. When the corrosion reaches a certain level, it will enter the fault state, the reliability will be reduced or even the performance will fail, which cannot meet the requirements of the safe operation of the power system.
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example
[0071] Choose Q235 steel in coastal areas,
[0072] W=f c v,
[0073] By calculating w=0.877(mm / a);
[0074] S g1 =Ig / c·t e -2 , the stable value of short-circuit current Ig flowing through the grounding wire is calculated according to 75% of the maximum short-circuit current of the busbar in the 220kV substation field area, that is, Ig is 46.319×0.75=34.74kA, and c is 70. t e = 0.2s.
[0075] S g1 =Ig / c·t e -2 =34.74×10 3 / 70·0.2 -2 =221.94mm 2
[0076] n select 1 year.
[0077] S g2 =(A-2×w×n)(B-2×w×n)=(6-2×0.877×1)(60-2×0.877×1)
[0078] =247.31mm 2
[0079] by S g1 and S g2 The comparative analysis shows that the service life of the grounding grid in this area is 1 year.
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The invention relates to an evaluation method of transformer substation grounding grids. The evaluation method comprises the following steps: (1) deriving the thinning speed of metal thickness of a grounding grid by applying the faraday's law; (2) determining the minimal section area Sg of a grounding wire without considering corrosion; (3) determining the minimal section area Sg2 when considering the influence of the corrosion factor; and (4) determining the evaluation years of the grounding grid. According to the method, the calculation process is clear, the accuracy rate is high, and the theoretically powerful support is provided for the safety running of a power system grounding grid.
Description
technical field [0001] The invention belongs to the technical field of substation grounding grids, in particular to an evaluation method for substation grounding grids. Background technique [0002] Grounding technology involves numerical analysis and optimal design of electrical parameters of the grounding system, analysis of soil structure parameters, resistance reduction technology in areas with high soil resistivity, scientific measurement of grounding resistance, corrosion diagnosis technology of grounding grids, and impact characteristics of grounding devices. A large number of literatures show that the main research results of the grounding grid are concentrated in three aspects. One is the testing, analysis and optimal design of grounding system parameters. Not only grounding impedance, but also its step voltage, contact voltage and potential distribution on the grounding grid should be considered. Secondly, the electrical integrity, heat capacity, and resistance of ...
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IPC IPC(8): G01N17/00
Inventor 郭军科于金山苏展卢立秋郝春艳邵林刘鸿芳其他发明人请求不公开姓名
Owner STATE GRID CORP OF CHINA
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