Medium-high voltage single-core crosslinked cable induction voltage and circular-current online detection method and device

Abstract

The invention discloses a medium-high voltage single-core crosslinked cable induction voltage and circular-current online detection method and a device. The method comprises the following steps: a load-current sensor is sheathed on a cable body under the charged operation condition so as to couple cable load current; a grounding current sensor is sheathed on a cable metallic protecting layer grounding outgoing line so as to couple grounding current of the metallic protecting layer; and the induction voltage of the cable metallic protecting layer is obtained by an induction voltage pickup probe clamped between a fracture of the cable metallic protecting layer grounding outgoing line and a grounding electrode or between the metallic protecting layer outgoing line of a cable line protection grounding side and the grounding electrode. The induction voltage and circular current values of the medium-high voltage single-core crosslinked cable metallic protecting layer can be obtained by optical fiber, an upper computer and a lower computer under the charged operation condition, thus providing effective reference for diagnosing and evaluating the health condition of the cable metallic protecting layer and an outer protecting layer, and providing a technical basis for adjusting and optimizing the grounding mode of the cable line and selecting the types of protects of protecting layers by a cable operation unit.

Description

technical field [0001] The invention belongs to the field of on-line detection, and relates to a method and device for on-line detection of induced voltage and circulating current of a medium-high voltage single-core cross-linked cable, which is suitable for voltage levels of 10 (6) kV to 35 kV. Background technique [0002] Cross-linked polyethylene (XLPE, hereinafter referred to as XLPE) cables have become the first choice for cable development and engineering applications due to their simple manufacturing process, easy installation and laying, excellent electrical performance, large transmission capacity, convenient operation and maintenance, and no oil leakage hazards. mainstream. [0003] With the development of urban modernization, a large number of urban distribution network lines use underground cross-linked cables instead of overhead transmission lines, and the proportion of medium and high-voltage single-core cross-linked cross-linked cables with large cross-sectio...

AI Technical Summary

Problems solved by technology

The amplitude of the induced voltage is proportional to the length of the cable line and the current flowing through the conductor. When the cable line is very long, the amplitude of the induced voltage on the metal sheath can reach a level that endangers personal safety; especially when a short circuit fault occurs in the cable line, Or when subjected to operating overvoltage or lightning overvoltage, a high induction voltage will be formed on the metal sheath, which may even break down the sheath insulation or cause a cable line operation accident

In addition, if the grounding method is not selected properly (for example, both ends of the metal sheath of a long-distance line are directly grounded), the induced voltage will cause a circulating current in the metal sheath, resulting in energy loss and a large amount of Joule heat, which seriously affects the current carrying capacity of the cable. Reduce the safe operating life of the cable

[0005] Domestic cable operation and testing departments have basically used the traditional method of manually measuring the induced voltage and induced circulating current of the metal sheath to evaluate the operation status and grounding reliability of the cable sheath, which is labor-intensive, inefficient, low in measurement accuracy, and automation. Low-level problems, lack of effective means to achieve real online detection

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