Online monitoring method for covert faults and joint process defects of power cable

Abstract

The invention discloses an online monitoring method for covert faults and joint process defects of a power cable. The online monitoring method comprises seven steps, namely current acquisition, fault recording, data caching, data transmission, map drawing, comprehensive analysis and fault positioning. The online monitoring method comprises the specific steps of: acquiring transition and mutation of transfinite current of all earthing points in a cable sheath layer by using a current transformer arranged on the cable; uploading the acquired data to a monitoring host by a fault recording device connected with the current transformer; transmitting the received data to a monitoring platform in a TCP / IP (Transmission Control Protocol / Internet Protocol) Ethernet interface manner by the monitoring host; and carrying out comparative judgment, fault reason analysis and fault segment positioning on the acquired transition and mutation data of the transfinite current according to a specific analytic method by a server arranged in the monitoring platform. According to the system, the early finding of the covert faults and the joint process defects of the power cable can be realized and the basis for ensuring long-term normal operation of the power cable is provided; and comprehensive monitoring, accurate fault positioning and early warning can be realized.

Description

Technical field [0001] The invention relates to the field of power technology, in particular to an online monitoring method for power cable hidden faults and joint process defects. Background technique [0002] With the continuous development of the power industry, the urban overhead line transmission is being replaced by underground high-voltage cables, so the number of underground high-voltage cables is rising sharply. [0003] Under a strong electric field, the power cable forms a water tree inside the insulator due to the combined effect of the damp or water-immersed environment and internal local defects. As the overall dielectric loss of the cable continues to increase with the operating life, the water tree will quickly develop into electrical branches. Electrical tree branches will cause the insulation breakdown of the cable body when the partial discharge occurs; due to the failure of the cable sheath insulation, the metal sheath will be grounded at multiple points, which ...

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Problems solved by technology

[0003] Under a strong electric field, due to the joint action of the humid or water-immersed environment and internal local defects, water trees are formed inside the insulator, and the overall dielectric loss of the cable continues to increase with the operating years, and the water trees will soon develop into electrical branches. The electric tree branch will cause the insulation breakdown of the cable body with the occurrence of partial discharge; due to the failure of the cable sheath insulation, the metal sheath will be grounded at multiple points, causing the increase of the sheath circulation, increasing the loss of the sheath, and affecting the cable. In severe cases, the cable may even be severely heated and burnt.

[0004] The cable joint is installed on site, which is greatly affected by human factors, and it is easy to leave defects and hidden dangers. The grounding point cannot be effectively grounded due to various reasons, causing the potential of the cable metal sheath to rise sharply to several thousand volts or even tens of thousands. Volt breaks down the outer sheath of the cable and continues to discharge at the breakdown point, causing the temperature of the outer sheath of the cable to rise or even catch fire

[0005] At present, the management of cable channels by most power supply management departments is still in the planned maintenance stage. Generally, regular inspections are used to check the operating status of cable channels and high-voltage cable lines laid in cable channels, and there is no effective monitoring. For cable channels The equipment such as high-voltage cable lines laid in cable channels lacks protection, and there are great potential safety hazards

From an economic point of view and a technical point of view, planned maintenance has great limitations, regular testing and maintenance have caused a lot of direct and indirect economic waste, and many insulation defects and potential failures cannot be found in time

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