Transformer Vibration Signal Detection And Analysis Based On FBG Sensor

The safe operation of transformer is of great significance to power system,and on-line monitoring of operation status is imperative.Vibration detection is a new method proposed at home and abroad in recent years to monitor the condition of transformer winding and core,which is one of the reliable and effective detection methods.There are three core issues in the transformer monitoring technology based on vibration analysis method: first,what technical means to collect the vibration signal on the surface of the transformer casing;second,how to extract the effective characteristic quantity in the vibration signal that can reflect the transformer operation state;third,what analysis method to establish the transformer safety state model for the effective characteristic quantity of the vibration signal.Firstly,focuses on the demand of large transformer vibration spectrum monitoring,presenting the theories of transformer working principle,transformer vibration generation mechanism,transformer vibration electromagnetic analysis and vibration signal analysis.Secondly,a comprehensive introduction of optical fiber sensor is provided,and its characteristics and advantages in special working environment are introduced.Thirdly,the basic principle of fiber grating sensing is studied,and the mechanical model of the sensor is analyzed mathematically.The sensor is designed from two aspects of finite element simulation and actual shape,and the test experiment of fiber grating vibration sensor is completed.Among them,the spectral characteristics of array multi-element FBG vibration acceleration sensor are tested in three different placement modes: Forward placement,side placement and reverse placement.The sensitivity is tested and improved.The test experiment consists of the preliminary test after the sensor is packaged,the test after the spring leaf inside the sensor is adjusted,and the sensitivity test after the sensor is finally added with high viscosity damping grease,so as to obtain the suitable vibration frequency response of the sensor;Then carry out the theoretical research on the demodulation algorithm of transformer vibration signal,and study the algorithm of phase demodulation method based on high-sensitivity interferometer,the non-equilibrium fiber interferometer and phase generation carrier(PGC)demodulation algorithm used to build a high-resolution dynamic fiber grating demodulation system;Based on the above research on vibration sensor and sensor demodulation,the transformer vibration signal detection system is laid out combined with the advantages of optical fiber sensing and interferometric wavelength demodulation technology.From three aspects of technical route,system structure design,system module design and site installation layout,an effective transformer vibration signal detection and analysis system is finally formed;Finally,by analyzing the transformer vibration signal for time-frequency characteristics,single-frequency signal characteristics,wavelet analysis,and energy spectrum analysis,a preliminary understanding of the vibration signal’s characteristics under transformer operating conditions can be gained.The state characteristic amount can be determined based on the vibration characteristics of the transformer winding and core,in order to judge the transformer’s operating condition and communicate with the substation’s main control center to provide a preliminary judgment conclusion.A series of intelligent technologies have been applied in this field,and some diagnostic and monitoring effects have been achieved.The use of these technologies still depends on users’ experience or random factors,and the stability and reliability of transformer condition monitoring technology need to be further improved.