Method for preventing OPGW optical cable connected to substation structure from being broken by lightning strokes

Abstract

The invention relates to a method for preventing an OPGW optical cable connected to a substation structure from being broken by lightning strokes. The method is characterized in that the method includes the following steps: (1) a down lead of the OPGW optical cable is laid along the substation structure and is fixed to the substation structure through a fixing cable clip with an insulating rubber pad, and it is guaranteed that the distance between the down lead of the OPGW optical cable and the substation structure is larger than 20mm; (2) the excessive portion on the lower portion of the down lead of the OPGW optical cable is wound on an excessive-cable frame, and the portion between the down lead of the OPGW optical cable and the substation frame is insulated; (3) the connection portion at the lower end of the down lead of the OPGW optical cable is connected with a metal-free optical cable through a connector box, and the connector box guarantees that the portion between the down lead of the OPGW optical cable and the structure is insulated; (4) the portion between the upper end of the down lead of the OPGW optical cable and the upper end of the substation structure is connected with a first grounded wire, and the portion between the middle of the down lead of the OPGW optical cable and the middle of the substation structure is connected with a second grounded wire. According to the method, it is guaranteed that currents can smoothly flow through an OPGW and be grounded on short-circuited situations or during lightning strokes, and the OPGW cannot be burnt out, namely, the OPGW is not broken.

Description

technical field [0001] The invention relates to a method for connecting an OPGW optical cable to a substation frame, in particular to a method for preventing strand breakage caused by lightning strikes when an OPGW optical cable is connected to a substation frame. Background technique [0002] OPGW optical cable has the dual functions of ordinary overhead ground wire and communication optical cable, so it is widely used. When the OPGW optical cable is connected to the substation frame (gantry frame), it is different from the ordinary overhead ground wire: after the OPGW enters the substation frame, it must continue to be guided down along the frame, and is connected with the ordinary metal-free optical cable entering the communication room to form an optical fiber communication transmission channel. [0003] In DL / T621-1997 "Grounding of AC Electrical Installations", it is stipulated: "The electrical installations of substations should be connected to the lightning protecti...

AI Technical Summary

Problems solved by technology

However, with the introduction of the OPGW optical cable, problems also appeared: the OPGW erection method is different from the ordinary ground wire, and the relevant regulations do not specify the grounding method and grounding position of the OPGW with a vertical down-conductor, resulting in the OPGW optical cable down-conducting method. irregular

At present, there are different opinions and disputes about the way of laying and installing OPGW into the substation frame, and the technical specifications for design, construction, and acceptance of this part have not been promulgated so far, resulting in the widespread phenomenon of random laying and installation.

After being put into operation, the OPGW is broken down and melted in the lower part of the substation structure, which seriously affects the safety and smoothness of the power communication system.

[0004] In recent years, the company's jurisdiction system has repeatedly experienced optical cable failures caused by substation OPGW optical cables introduced into the substation structure, which seriously affected the safety of the power grid and communication network.

For example: 1. In March 2010, the OPGW outer body of the 220kV Wangmen Line connected to the Wangzhuangyu substation frame side had a high-temperature heating phenomenon at the contact point of the OPGW outer body with the metal components of the substation frame, causing the OPGW outer stranded wire to fuse 3 2. In January 2011, the OPGW outer body of the 110kV Fuyong Line connected to the Fushan substation frame side had multiple severe arc burns at the contact point of the OPGW outer body with the metal components of the substation frame, resulting in twisting of the OPGW outer layer. The wire gradually melts and breaks, eventually damaging the inner stainless steel tube and optical fiber core, resulting in interruption of communication services in operation

[0005] According to the analysis of the fault, the most vulnerable part of the OPGW optical cable under the frame is the place where the OPGW and the metal components of the frame are connected but not connected. On the upper end, OPGW discharges electricity to the frame next to it and the top nails on the frame, causing damage to the optical cable

2) The top of the OPGW down-conductor is short-circuited with the frame, and the lower end of the frame is not properly grounded, causing the OPGW optical cable to discharge to the remaining cable rack and cause damage to the optical cable

3) The optical cable and the metal hoop of the substation frame are close together but not fixed, and the gap is easy to change

The OPGW optical cable is in contact with the surrounding metal parts on the outer surface. The large resistance at the contact will generate a lot of heat when the induced current flows through it. After the long-term action of the induced current, the OPGW optical cable will be gradually fused, resulting in damage to the fiber core.

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