Method for accurately calculating power harmonic wave parameters through adopting time delay Fourier transform frequency measurement method

The invention provides a method for accurately calculating power harmonic wave parameters through adopting a time delay Fourier transform frequency measurement method, and belongs to a method for automatically monitoring an analytical instrument and an automatic monitoring device used for voltage and current waveform distortion of various power networks. The method includes the following steps: firstly, truncating sampled power harmonic wave signals through adopting a symmetrical window function; performing fast Fourier transform (FFT for short) for the truncated signals; truncating sampled power signals of the same length through adopting the same symmetrical window function at a time delay L point of the sampled power harmonic wave signals, and performing FFT for the truncated signals; accurately calculating out the fundamental wave and the frequency of each harmonic wave as per the phase difference of angle of the FFT performed for two times; calculating out the fundamental wave and the correction factor of each harmonic wave through adopting the method of interpolation in the frequency domain of the dissymmetrical window function; and finally, calculating out the amplitude value and the phase position of each power harmonic wave. The method provided by the invention has remarkable advantage with respect to the time spent in calculation as compared with other windowed FFT interpolation correction and analysis methods, best suits the DSP with hardware FFT, and is a practical algorithm.