Cable insulation monitoring method and system based on high-voltage power frequency and low-voltage ultra-low frequency

A cable insulation and ultra-low frequency technology, applied in the direction of measuring electricity, measuring devices, measuring electrical variables, etc., can solve the problems of inability to timely and accurately evaluate the aging state of cable insulation, achieve small amplitude, easy detection, and reduce interference Effect

CN111323681BActive Publication Date: 2021-01-19HUAZHONG UNIV OF SCI & TECH
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Patent Information

Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Publication Date
2021-01-19

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Abstract

The invention discloses a cable insulation monitoring method and system based on high-voltage power frequency and low-voltage ultralow frequency, and belongs to the field of cable insulation monitoring. The method comprises the steps: coupling a low-voltage ultralow frequency signal in a high-voltage power frequency cable line; respectively measuring zero-sequence ultralow-frequency active and reactive power average values at the head and tail ends of each line; calculating the average value and the standard deviation of the ultralow-frequency dielectric loss of each line; judging whether theaverage value and the standard deviation of the ultralow-frequency dielectric loss exceed set thresholds or not; calculating correlation coefficients between adjacent lines, and comparing the correlation coefficients with the average correlation coefficient; calculating the change rate of the ultralow-frequency dielectric loss average value of each line, carrying out normalization processing to construct a distribution function, solving the insulation degradation probability, and outputting the insulation degradation probability when the insulation degradation probability is greater than the basic proportion. According to the invention, on the premise of realizing cable insulation online monitoring, various data processing methods are utilized to formulate an evaluation basis for a specific line, and the cable insulation state is evaluated timely and accurately.
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Description

technical field

[0001] The invention belongs to the field of cable insulation monitoring, and more specifically relates to a cable insulation monitoring method and system based on high-voltage power frequency and low-voltage ultra-low frequency. Background technique

[0002] Most cable insulation breakdown accidents are caused by water tree branches, which is due to the low voltage of water tree branches under AC voltage. Impurities, protrusions, etc. form high electrical stress, and the insulation is damp to further promote the generation of water branches. In fact, water tree branch grows slowly, and its partial discharge signal is weak, which is not easy to detect. Once water branches induce electric branches, the insulation damage will be accelerated, and insulation breakdown may occur in a short time. Therefore, early detection of cable insulation defects is of great significance.

[0003] At present, the cable insulation monitoring methods mainly include partial dis...

Examples

Embodiment Construction

[0063] 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 conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described here are only used to explain the present invention, not to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not constitute a conflict with each other.

[0064] like figure 1 As shown, a cable insulation monitoring method based on high-voltage power frequency and low-voltage ultra-low frequency includes the following steps:

[0065] (1) In a power grid composed of multiple cable lines, couple low-voltage ultra-low frequency signals to cable lines where low-voltage ultra-low frequency signals do not exist;

[0066] (2) Collect the zero-sequence ...