Research Of Temperature On-line Monitoring System For Power Cable Based On Optical Fiber Grating

In modern industry, the electrical equipment running abnormality or failure often occurs due to abnormal changes of temperature. So we can implement real-time temperature detection for power cable in the key regional and failure incidence to grasp cable running change timely and accurately. Traditional electrical signal sensors require additional power, and be susceptible by electromagnetic interference, and can’t meet the needs of real-time temperature detection of power cable. Optical fiber sensor is a passive component with wavelength encoding, it has a lot of excellent characteristics such as multi-measurable parameters, high measurement precision, strong multiplexing capability, high temperature resistance and resistance to electromagnetic interference. Yet the optical fiber sensor can combine "sense" and "pass", it is very suitable for on-line power cable temperature detection system.The main research of this thesis is as follows:First, the types and reasons of power cable fault are analyzed. We predict the development advantages of the fiber Bragg grating in the future temperature measurement based on the in-depth study of on-line power cable temperature detection technology research at home and abroad. This paper’s research direction is explicit.Second, the principle of fiber Bragg grating sensor are introduced in detail, and the optical fiber Bragg grating Bragg formula for optical transmission characteristics based on the coupled-mode theory; By comparing the advantages and disadvantages of several commonly used fiber Bragg grating sensing signal demodulation method, we decide to use the adjustable F-P filter demodulation technology to finish the power cable temperature signal demodulation.Thirdly, according to the cooling condition of the underground buried cable and the knowledge of heat conduction, the two-dimensional heat conduction differential equation of underground cable temperature field is established. By setting the initial and boundary conditions, power cable temperature field is simulated by using ANSYS software; The transient and steady-state thermal road model of the power cable is designed to calculate electricity load flow and temperature value at every point. Finally, a set of on-line power cable temperature detection system is designed based on fiber Bragg grating, and complete the related light path, circuit integration building. The circuit has carried on by the simulation test, the visual interface and PC monitoring software of the temperature is developed in the LabVIEW8.6environment. The system is verified under laboratory conditions. The thermocouple sensor is installed as a reference to compare the following features. The results show that the fiber Bragg grating cable temperature on-line detection system’s precision is higher, and it has a certain practical value.