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A cable insulation monitoring method and device

A cable insulation and cable technology, which is applied in the field of cable insulation monitoring methods and devices, can solve the problems of small leakage current, extraction, and current measurement difficulties, and achieve the effects of large monitoring range, high measurement accuracy, and high industrial application value

Active Publication Date: 2021-05-28
TSINGHUA UNIV
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  • Application Information

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Problems solved by technology

However, the current online monitoring methods for the leakage current in underground cables are mainly limited by the following difficulties: 1. The leakage current representing the aging state of the insulation is usually very small, and it is difficult to extract it from the larger positive sequence current of the load; 2. Leakage current is often characterized by three-phase symmetry, which brings great difficulties to current measurement

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  • A cable insulation monitoring method and device
  • A cable insulation monitoring method and device
  • A cable insulation monitoring method and device

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Embodiment Construction

[0047] In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. It should be understood that these descriptions are exemplary only, and are not intended to limit the scope of the present invention. Also, in the following description, descriptions of well-known structures and techniques are omitted to avoid unnecessarily obscuring the concept of the present invention.

[0048] The invention proposes an on-line cable insulation monitoring method that can be applied to underground cables of distribution networks.

[0049] It works as follows:

[0050] figure 1 Shown is a common medium voltage distribution network system structure diagram. The three-phase power supply is changed to the rated voltage of the distribution network through the transformer, and then the electric energy is tran...

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Abstract

A cable insulation monitoring method and device, the method comprising the steps of: injecting a common mode voltage into a cable to be tested; measuring and recording the three-phase current of the cable to be tested under normal conditions; monitoring the three-phase current of the cable to be tested in real time; The three-phase current of the three-phase current is compared with the three-phase current under normal conditions to obtain the insulation leakage current of the cable to be tested; the aging degree grade of the cable to be tested is obtained according to the insulation leakage current. The invention can realize the monitoring of the whole process of cable insulation aging, and the monitoring effect is not affected by the cable length and system load, and the monitoring effect is stable; in addition, it will not have any influence on the normal operation of the system load, and has good online monitoring performance.

Description

technical field [0001] The invention relates to the field of on-line monitoring of cable insulation status, in particular to a cable insulation monitoring method and device. Background technique [0002] At present, the on-line monitoring methods of cable insulation state at home and abroad are mainly divided into two categories: the method based on partial discharge monitoring and the traveling wave monitoring method based on the principle of time domain reflection. The partial discharge monitoring method mainly collects partial discharge signals by placing a high-frequency current sensor at one end of the cable, and describes the insulation state of the cable through the frequency and intensity of partial discharge. The traveling wave monitoring method based on the principle of time domain reflection mainly injects a special signal at one end of the cable. At the position where the cable is seriously aging, due to the change of impedance, the injected signal has catadioptr...

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01R31/12G01R19/00
CPCG01R19/0092G01R31/1272
Inventor 张品佳吴阳
Owner TSINGHUA UNIV