High accurate measurement method on phase difference

A new accurate measurement method on phase difference between two sinusoidal signals in power system was presented. For asynchronized sampling, the principle of discrete Fourier transform was analyzed and the expressions of short-range spectrum leakage and negative frequency spectrum leakage effects were obtained. Then a new interpolation method was presented using the positions, the real parts and the imaginary parts of two spectral lines with the largest and larger magnitudes in discrete spectrum of the sampled signals. The method could eliminate the short-range and the negative frequency spectrum leakages at one time. The results of simulations and practical measurements show the presented interpolation algorithm can reduce apparently the spectrum leakages, especially the negative frequency spectrum leakage and can be applied in measuring the smaller phase with higher accuracy.