Research on Calibration Method of Electronic Transformer Based on Correlation and Lattice Notch Filter

Abstract

The calibration method of electronic transformer is one of the key technologies to ensure the gradual improvement of reliability and accuracy. For the phenomenon that the electronic transformer is affected by working condition, the measurement signal contains harmonics, noise and frequency fluctuation, a calibration method based on correlation and lattice notch filter is proposed. The simplified adaptive lattice notch filter is used to preprocess the collected data and extract frequency, filter out the interference of harmonics and noise, and improve the precision of the ratio error. And the interpolation correlation method which is not sensitive to noise and harmonic is used to calculate the phase difference. For the non integral period sampling caused by frequency fluctuation, the sampling data is interpolated according to the size of frequency offset. This process achieves the integral period sampling and further improve the calibration precision of angle error. Simulation results show that under the strong harmonic and noise interference the proposed method can filter out interference signals and overcome the influence of frequency fluctuation. And the results of calibrating measured data of electronic transformer show that the algorithm can fully satisfy the calibration requirements of 0.2 level electronic transformer.