Research On Wireless Zinc Oxide Arrester Electrified Tester Based On Harmonic FFT Analysis

With the continuous development of the power grid,the importance of zinc oxide arresters as the protection side equipment of the power grid continues to increase.In order to ensure the safe and stable operation of the power grid,a wireless zinc oxide arrester live tester can be used to detect the leakage current parameters of the arrester,and judge the operation of the arrester based on the harmonic parameters.Fast Fourier Transform(FFT)algorithm is difficult to achieve full cycle truncation when detecting harmonics.The resulting spectrum leakage and fence effect will affect the results of harmonic detection.Windowing and correction algorithms can improve the harmonic parameters.For the extraction accuracy,this paper first selects a correction algorithm based on the ratio of the two discrete spectral lines with the largest amplitude and the second largest amplitude closest to the harmonic frequency point to correct the ratio formula of the harmonic parameters.At the same time,the correction formula is derived by using the window spectrum function.And verified its effectiveness and ease of realization in an experimental environment.In order to solve the problem of digital signal processing performance degradation caused by data truncation in the traditional FFT analysis method for harmonic detection,this paper selects an all-phase FFT analysis method that considers all possible data truncations of a sample point.Based on this method,all-phase is selected.Time-shift phase difference correction algorithm,while using the window spectrum function to derive the correction formula,the simulation results show that compared with the FFT-based ratio formula correction algorithm,the analysis accuracy of the harmonic detection is improved in the case of no noise and noisy(50d B)respectively.4～5 orders of magnitude and 1～2 orders of magnitude,and the frequency estimation deviation of the small signal harmonic components does not exceed0.6Hz,and the phase estimation deviation does not exceed 0.5°,which realizes the improvement of detection accuracy and the estimation of small signal parameters,and Its effectiveness and high precision are verified in an experimental environment.At the end of this paper,the hardware and software system of the wireless zinc oxide arrester live tester based on the correction algorithm is designed,and the solutions to the problems in the actual operation are introduced in detail.