Time-Domain Quasi-Synchronous Sampling Algorithm for Harmonic Analysis Based on Newton's Interpolation

In the case of asynchronous sampling, spectral leakage has a harmful effect on the accuracy of harmonic analysis. This paper presents a new harmonic analysis algorithm, which successfully adjusts an actual sampling sequence to an ideal sampling sequence synchronized with the original signal. First, a fundamental period is evaluated by a zero-crossing technique, and then, according to this fundamental period, the sampling sequence is reconstructed by the time-domain Newton's interpolation polynomial. Simulation results show that the proposed algorithm has high accuracy in measuring distorted and noisy signals by reducing spectral leakage effectively in the framework of the International Electrotechnical Commission standards. Moreover, the proposed method maintains high measurement accuracy for nonstationary and slow-changing signals even at low-frequency resolution. The results of the field experiment confirm the effectiveness of this algorithm under practical considerations.