Application of the hottest power optical fiber in

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Application of power optical fiber in relay protection

as the channel medium of relay protection, optical fiber has the advantages of not afraid of ultra-high voltage and lightning electromagnetic interference, insulation to electric field, large transmission capacity, wide frequency band, low attenuation and rich resources. With the gradual improvement of power optical fiber network, optical fiber protection will be more widely used in the field of relay protection

1 working principle of optical fiber

1.1 structure and classification of optical fiber

optical fiber is the abbreviation of optical fiber, which is composed of thin glass fiber with a diameter of about 0.1 mm. The optical fiber used for relay protection is communication optical fiber, which is composed of fiber core and cladding: the fiber core area completes the transmission of optical signals, and the cladding is to enclose the light in the fiber core, protect the fiber core and increase the mechanical strength of the fiber. Reduce environmental impact

according to the transmission mode of light in the optical fiber, the optical fiber can be divided into single-mode optical fiber and multimode optical fiber. The central glass core of multimode fiber is thick and can transmit multiple modes of light, but its large inter mode dispersion limits the frequency of digital signal transmission, and its limiting effect is more obvious with the increase of distance. The central glass core of the single-mode fiber is very thin, and can only transmit one mode of light. Therefore, its inter mode dispersion is very small, which is suitable for long-distance transmission. However, there are still material dispersion and waveguide dispersion, so the single-mode fiber has high requirements for the bandwidth and stability of the light source, narrow bandwidth and good stability

1.2 characteristics of optical fiber for relay protection μ M is a low loss window of optical fiber, so the optical fiber for relay protection uses single-mode optical fiber, 1.3 μ M wavelength band

2 power optical fiber network and power optical cable

2.1 current situation of power optical fiber network

the transmission performance, stability and adaptive protection recovery ability of optical fiber network play a key role in the reliability of optical fiber relay protection. At present, in the field of power network communication, sdh/sonet synchronous digital system based on electrical time division multiplexing is widely used. It has strong protection and recovery ability and fixed delay performance. However, the method of using electrical time division multiplexing to improve the transmission capacity has certain limitations, which makes it difficult to meet the requirements of the group in the power network, which presents high-speed capacity expansion and complex topology. Therefore, it will be the inevitable development direction of the power optical fiber network to change from the current electrical multiplexing mode to the optical multiplexing mode. The optical multiplexing modes include optical time division multiplexing, wavelength division multiplexing and frequency division multiplexing, among which the wavelength division multiplexing technology has gradually entered the general situation of large-scale commercial stage 1. Since the capacity expansion potential of the electric time division multiplexing system has been exhausted, the available bandwidth resources of 200 mm of optical fiber are available. Only less than 1% is used. If multiple light source signals with appropriately staggered transmission wavelengths are transmitted on one optical fiber at the same time, the information transmission capacity of the optical fiber can be greatly increased. This is the basic idea of wavelength division multiplexing. The main advantage of using WDM system is to make full use of the huge bandwidth resources of optical fiber, so that the transmission capacity can be rapidly expanded by several times or even hundreds of times. In large capacity long-distance transmission, a large number of optical fibers and regenerators can be saved, and the transmission cost can be greatly reduced. Wavelength division multiplexing technology has considerable development potential in power optical fiber network, which can save the cost of long-distance transmission of power optical fiber and improve the reliability of power optical fiber network transmission. Therefore, with the gradual maturity and evolution of wavelength division multiplexing technology, wavelength division multiplexing technology will be widely used in power protection optical fiber network

2.2 power optical cable

at present, the year-on-year growth is 49%. There are three main types of optical cables used in power optical fiber network: ordinary non-metallic optical cable, self-supporting optical cable and overhead ground wire composite optical cable. It can be found that although the overhead ground wire composite optical cable has a high cost, it accounts for a low proportion in the overall cost of the line when it is used in high voltage level and double circuit and multi circuit lines on the same pole, and can also be used as a relay protection channel. Taking a 220 kV line as an example, the price of using optical fiber protection is equivalent to that of using high-frequency protection. However, wave arresters, coupling capacitors, combination filters and other equipment need to be added on both sides of the high-frequency protection road. The overhead ground wire composite optical cable is more economical, and has the advantages of high reliability and low maintenance cost. With the decline of the comprehensive price of optical cable, overhead ground wire composite optical cable will be widely used in power optical fiber network

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