Research And Implementation Of Transformer Winding Deformation Signal Filtering Method In Strong Noise Background Based On FPGA

The power transformer is an important upstream device of the power system.Therefore,detecting the deformation of the power transformer winding is of great significance to the safe operation of the power grid.Firstly,for the problem that the conventional filtering method can not accurately extract the amplitude of the target sinusoidal signal this paper adopts the cross-correlation detection principle of target signal and noise uncorrelated to design the digital filtering in time domain and frequency domain algorithm to achieve the purpose of noise suppression and amplitude extraction..Secondly,the two filtering algorithms are simulated under different conditions in Matlab.The simulation results show that the amplitude detection errors of the sinusoidal signals in the time domain and frequency domain digital filtering methods is 2.06%and 2.32%respectively,under the strong noise interference of-15dB grid basic harmonic noise and-5dB Gaussian white noise.According to the phase shift simulation result,the algorithm calculates the cross-correlation function sequence as n=N-99-N+99,which is 199 points.Finally,the FPGA implementation of the time domain digital filtering algorithm is studied,and the filtering algorithm is integrated into the prototype of the transformer winding deformation detecting device for experiment.The experimental results show that the digital filter can attenuate the noise signal up to 44.5dB;After adding the filtering algorithm,the amplitude-frequency characteristic curve burr of the transformer winding deformation offline detection is significantly improved;The response signal of the on-line detection of 200kHz transformer winding deformation is-68dB,and the error of Matlab simulation result is less than 0.5%,which indicates the correctness of the digital filtering algorithm FPGA implementation.The error of the filtering result of the experimental data of multiple sets of experiments is within 1dB,which is in line with China's power industry standards,and the feasibility of the design of the online detection engineering of transformer winding deformation is preliminarily verified.