Performance Improvement of Window and Interpolation Algorithm in TTU Harmonic Analysis Module

In order to improve the real-time performance and accuracy of harmonic analysis in transformer terminal unit (TTU), the principles of the Hanning window and interpolation algorithm, the Blackman-Harris window and interpolation algorithm are introduced. The hardware implementation of harmonic analysis module in TTU is primarily analyzed. The numerically generated voltage signals with harmonic and noise are used to compare the calculation speed of the two algorithms. The accuracy of harmonic analysis of the two algorithms is compared under different sampling durations, sampling frequencies and total harmonic distortions (THDs). The results show that the accuracy of the Hanning window and interpolation algorithm is better than that of the Blackman-Harris window and interpolation algorithm, and the computation time of the former is only 1/3 of that of the latter. In the harmonic analysis module of TTU, the Hanning window and interpolation algorithm is recommended. The sampling duration should be not less than 0.1 s and the sampling frequency should be not less than 2 kHz.