The power system network has a complex structure and wide distribution, and there are various hidden dangers in high-voltage power lines and power communication networks. Therefore, it is particularly important to carry out distributed monitoring of various lines and networks in the system.
At present, distributed fiber optic temperature sensor products have been developed abroad using the laser Raman spectrum effect. And China is also actively carrying out research work in this area. China's research work on introducing distributed optical fiber temperature sensing technology into power system cable temperature measurement is just beginning. Considering the snow disaster suffered, if sensing optical cables can be laid in parallel on high-voltage cables, and the temperature, pressure and other parameters of power system cables, iron towers and other facilities can be measured in real time, risks can be eliminated in time, thereby reducing as much as possible. Economic losses. It can be seen that the optical fiber sensor will have a wide range of application prospects in the power system.
Ideally, the fiber should be placed as close as possible to the cable core to more accurately measure the actual temperature of the cable. For directly buried power cables, although surface-mounted optical fibers cannot accurately reflect changes in cable load, they are sensitive to changes in soil thermal resistivity where cables are buried, and can reduce the installation cost of optical fibers.
Electric power is the basic amount of electricity that reflects energy conversion and transmission in the power system. Electric power measurement is an important part of power metering. With the rapid development of the electric power industry, traditional electromagnetic measurement methods are increasingly showing their inherent limitations, such as electrical insulation, electromagnetic interference, magnetic saturation and other issues, so people have been working on finding new methods for measuring electrical power. It can be said that the applications of fibre optic sensors has brought good news to people to solve this problem.
The main features of the electric power optic sensor are: since the electric power sensing involves both voltage and current, it is usually necessary to consider the electro - optical and magneto - optical effects at the same time. The structure of the optical fiber electrical power sensor head is relatively complicated; the optical sensing signal of the optical fiber electrical power sensor sometimes contains both voltage and current signals, so the signal detection and processing methods will also be complicated.
There are many types of optical cables in power systems, among which temperature and stress are the main environmental factors that affect the performance of optical cables. Therefore, while monitoring the optical fiber breakpoint, the temperature and stress of the optical cable are also monitored, which shows that the early warning and maintenance of the optical cable has far-reaching significance. By measuring the frequency and intensity of Brillouin scattered light along the length of the fiber, the temperature and strain information of the fiber can be obtained, and the sensing distance is long, so it has far-reaching engineering research value.
The BOTDR optic sensor measures the self-published Brillouin scattering signal of the optical fiber, and its signal strength is very weak, but the coherent detection technology can be used to improve the system signal-to-noise ratio. This solution can work with a single light source and single end, the system is simple, the implementation is convenient, and the fiber breakpoint, loss, temperature and strain can be monitored at the same time.