Cable local-defect diagnosis method

Abstract

The invention provides a cable local-defect diagnosis method which includes the following steps: (1) extracting a natural propagation coefficient of a to-be-tested cable under an intact condition; (2) measuring an input impedance amplitude or a phase frequency spectrum at a head end of the to-be-tested cable; (3) constructing a way-side characteristic diagnosis function which reflects a way-side propagation coefficient change condition of the to-be-tested cable; (4) searching for a peak value point of the way-side characteristic diagnosis function, wherein the position of the peak value point is the position of a defect and the higher the peak value is, the more serious the defect is. Through implementation of the cable local-defect diagnosis method, accurate positioning and severity diagnosis of a local defect of a cable can be realized and potential safety hazards of the cable are reduced.

Description

technical field [0001] The invention relates to the field of electric technology, in particular to a method for diagnosing local defects of cables. Background technique [0002] Wires and cables play a major role in the transmission of electric energy and communication signals in electrical systems such as modern urban power grids, aircraft, rail transit, ships, and power plants, and their operating status directly affects the safety and stability of large electrical systems. Cables in actual operation often fail due to local defects, which mainly include local insulation aging and local external force damage. [0003] The power cables in the urban power supply system are laid in cable trenches or directly buried underground. The laying environment and usage status will greatly affect the life of the cables. Power cables operate under different soil, moisture, moisture, and temperature environments for a long time, and the insulation is susceptible to corrosion and penetrat...

AI Technical Summary

Problems solved by technology

[0005] There are a large number of cables with short length and high voltage level in nuclear power plants. The occurrence of nuclear power accidents often begins with local nuclear leakage. Under high-dose nuclear radiation, the organic polymer structure of cables will be destroyed and rapid aging will occur, which will lead to cable The failure makes the reactor out of control, which will eventually lead to a major safety accident in the nuclear power plant

[0006] It can be seen that if the local defects of the cable cannot be eliminated in time, it will cause serious economic losses and social impacts.

The existing time domain reflectometry (TDR) can use pulse signals to locate cable faults, but it is still unable to complete the diagnosis of local defects

Cable partial discharge location is a method to detect local defects, but it has the disadvantages of severe partial discharge signal attenuation, high technical requirements for partial discharge signal separation, and difficult multi-point partial discharge detection.

Existing cable detection technology still stays in the fault location, lack of fast and accurate diagnosis of local defects, can not eliminate the potential threat of the cable in time, can not prevent problems before they happen, so the new technology significance of the local defect diagnosis of the cable major

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