Surface potential pilot frequency comparison-based ground grid defect identification method and system
A surface potential, grounding grid technology, applied in fault location, measuring electrical variables, measuring current/voltage, etc., can solve the problems of no installation, no identification of grounding grid faults, etc., to achieve strong anti-interference ability, convenient detection, simple method effect
Active Publication Date: 2014-11-12
HUAZHONG UNIV OF SCI & TECH
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Problems solved by technology
[0006] At present, there is no method at home and abroad to identify ground grid faults by using the difference in frequency response of the ground surface potential of the ground grid, and there is no corresponding device
Method used
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Embodiment
[0041] In order to make the content of the present invention more clear and intuitive, for a certain simple ground network, the method and device provided by the present invention are used to identify the defects of the ground network.
[0042] The simple net only consists of two sections of 5m*50mm arranged side by side 2 *5mm horizontal carbon steel (Q235 steel) conductor. The two sections of conductors can be connected to the test circuit by the ground lead wire, and the soil is muddy soil covered by a thin layer of humus. In the experiment, the section of conductor that is not connected to the test loop can be considered as a faulty or defective conductor.
[0043] According to the actual detection data of the geological exploration subject, it can be judged that in this embodiment, the resistivity and dielectric constant of the soil do not change significantly with the frequency within 1 MHz. However, because the resistivity and inductance of the ground grid conductor v...
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The invention discloses a surface potential pilot frequency comparison-based ground grid defect identification method. Reference frequency point current and testing frequency point current are respectively inputted into any ground grid downlead of a ground grid to be identified, moreover, the surface potentials of the two frequency point currents respectively corresponding to a plurality of observed points are detected, and the surface potential difference between the two frequency point currents corresponding to each observed point, which is pilot frequency surface potential difference, is calculated; a pilot frequency surface potential difference-observed point variation curve is drawn, and according to the curve, the gray correlation algorithm or the fuzzy clustering algorithm is utilized to obtain the observed points with over-small or over-large pilot frequency surface potential differences, which are defective points. The invention also provides a system for implementing the method, which comprises a sinusoidal variable-frequency alternating-current power supply, a measurement circuit and a control center. By comparing the differences between surface potential responses when the ground grid is excited by currents with differential frequencies, the invention can identify the defects or faults of the ground grid, and compared with conventional methods, the method has the characteristics of convenient detection and high anti-interference capability, and is easy to operate.
Description
technical field [0001] The invention relates to a defect identification method of a grounding grid of a power generation and substation in an electric power system, and more specifically, a method for judging whether there is a defect in the grounding grid and locating the defect by using different frequency comparisons of surface potentials. Background technique [0002] The grounding grid of power generation and substation is one of the important measures to ensure the safe and reliable operation of the power system. When various faults, abnormal overvoltage or overcurrent occur in the power system, good grounding can quickly disperse large currents into the ground, avoiding equipment damage or personal injury caused by fault expansion. After the substation grounding grid is put into operation, it is buried in the ground all the year round. The conductors often undergo different types of corrosion due to the electrochemical corrosion of the soil, the electrodynamic action ...
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IPC IPC(8): G01R31/08G01R19/00
Inventor 张丹丹张蓬鹤贺家慧吴志威周吴
Owner HUAZHONG UNIV OF SCI & TECH