Study On Fiber-Optic F-P Sensor Suitable For Transformer On-line Partial Discharge Monitoring

The power transformer is the most important equipment of high voltage power grid, while the traditional methods of online partial discharge monitoring have some limitations. Based on many advantages of optical fiber sensing technology, this paper has done some research on fiber optics F-P sensing which can be used transformer on online partial discharge monitoring. This research may contribute to improve the reliability of power system safety monitoring. This article has done some work as follows.1. Making a brief analysis of fiber optics F-P sensing theory, including the diaphragm deformation, interferometer and demodulation principle.2. According to fiber optics F-P sensing principle and the beam propagation characteristics in optical fiber, doing a detailed calculation in order to pick out the best parameters of the sensor cavity length, the quartz diaphragm reflectivity, the effective radius and the diaphragm thickness. Making an analysis of the factors that may dominate the sensor performance, including the intensity of the interference fringes which is determinated by free spectral range (FSR), the light source wavelength, and the interference fringe visibility, the effective reflectivity of the quartz diaphragm, the sensitivity and response frequency. With considering the practical application of preparation, figuring out the proper parameters of the sensor, including cavity length, the quartz diaphragm reflectivity, the effective radius and the diaphragm thickness. These results not only provide a sufficient theoretical guidance for the following experiments and signal analysis, but also points out how to improve the performance of the sensor further.3. Designing a set for fiber optics F-P sensor preparation, and according to the fabrication procedure strictly making out the sensors. And then with the analysis of interference spectral information, working out the accurate wavelength of the peaks and troughs of the interference spectrum, calculating the practical cavity length and fringe contrast of the sensors, and then figuring out the curve of the practical cavity length and fringe contrast. The consistency of the sensor has been initially ensured.4. Building a reasonable signal demodulation system for fiber optics F-P sensing, Doing a preliminary analysis about online partial discharge signal monitoring, including researching on the different discharge intensity with three partial discharge means, the different measuring distance with a same discharge intensity, and then acquiring the signal data for a detailed analysis. The experiment results provides that using fiber optics F-P sensor to online monitoring partial discharge is feasible, but the sensor sensitivity still needs to improve for further researching.