Study On The FBG Monitoring Technology Of Transformer Internal Temperature In Ningxia Daba Power Plant

Power transformer serves as one of the most important equipments in the power system. Its reliability is directly related to the safety, efficiency and economy of the power grid operation. Most of the transformers end of life because of the loss of its insulation capability, which is mainly affected by the winding temperature of the transformer in operation. Notably, the temperature in the hottest district of the winding is regarded as the essential constraint on the transformer load. Given this, measuring the internal temperature of the transformer is of great significance for the permissible overload and the operational life assessment.The thesis presents a study on the characteristics of temperature rise with the heat generation and dissipate, which is followed by an analysis of the internal loss principle of the transformer and a discussion of the influence of its no-load and load loss on winding hot spot temperature. It also deduces the heating and cooling characteristic equations of winding, iron core and oil as the major components of the transformer, and the characteristic curves are given.Moreover, the FBG temperature sensor is chosen based on the status of the current fiber optic temperature sensor and the specific requirements of the internal temperature measurement of the transformer. After the comparison of the wavelength demodulation methods and a review of requirements of the subject, we select F-P tunable filter to demodulate the central wavelength of the FBG.Meanwhile, researches related to this are conducted, including the design of specific programs for the temperature measuring platform using FBG, selection of the appropriate hardware devices, construction of the measuring platform and acquisition of the data signals. Through the application of Lab VIEW, the signal processing program is designed and the calculation process is realized from the collected optical wavelength signals to the temperature signals. Then temperature calibration experiments of the FBG are conducted, followed by the performance tests. And the sensor errors, as well as the improving methods are discussed. Finally the temperature measuring platform is constructed for the temperature rise experiments of the oil-immersed transformer. The results show that the FBG temperature sensor can be an effective instrument to measure the internal temperature of the transformer with accuracy stability and quick response to the changes in temperature.