Diagnosis Of Transformer Winding Deformation Based On Frequency Response Complex Value And Gray Projection Method

The power transformer is one of the indispensable equipment for AC power supply system,The power supply stability and reliability of power system are dependent on normal and stable operation of power transformer.With the increase of the grid capacity,the fault rate of the transformer is on the rise.Among all the faults,the transformer winding deformation is one of the most common transformer faults.The analysis on the result of transformer winding deformation detection is still mainly rely on the experience of professional analysis,so the study of transformer winding deformation diagnosis method is helpful to improve the winding deformation detection efficiency,and is of great significance to the safe and steady operation of power system.A classification method of transformer winding deformation based on complex values of frequency response and gray projection method is proposed in this paper.The advantage of the classification method was analyzed theoretically.The effectiveness of the proposed method was verified by circuit simulation and experiment.The main work of this paper is as follows:A lumped parameter model for the continuous single winding of transformer was established.The amplitude frequency characteristic data and phase frequency characteristic data of transformer windings under four typical deformation faults,such as turn to turn short circuit,axial distortion,radial concave and radially convex exterior,were obtained by changing the value of capacitance and inductance parameters of the circuit model.The regularity results of frequency response analysis signature when winding deformation happen were summarized.A transformer winding deformation criterion considering both amplitude frequency characteristic data and phase frequency characteristic data was presented.The polar diagram of frequency response characteristic of transformer winding was obtained,and the transformation of the frequency response characteristic polar diagram of the transformer winding to the two dimensional matrix was realized by using MATLAB software.Then the gray projection method in digital image processing technology was applied to the extraction of transformer winding deformation feature vector.A transformer with a replaceable internal winding was fabricated to simulate the winding deformation test.The amplitude frequency characteristic data and phasefrequency characteristic data of the axial deformation and radial deformation of the winding were obtained.The corresponding feature vectors were extracted from the simulation data and the measured data,and the Fisher discriminant analysis method was used to diagnose the transformer winding deformation.The validity of the proposed method was verified.