Waveform distortion assessment in power systems with a new three-step sliding-window method

Discrete Fourier Transform (DFT) and high-performance signal-analysis techniques (i.e., Prony, ESPRIT, root-MUSIC methods) have been proposed to calculate Power Quality indices that characterize waveform distortions in power systems. DFT can be affected by spectral leakage problems that cause inaccuracies in the spectral component calculation while high-performance signal-analysis techniques usually involve onerous computational efforts. Recently, hybrid methods were proposed in the relevant literature which make it possible to calculate PQ indices with accuracy and more acceptable computational efforts. This paper proposes a new three-step hybrid method which applies alternatively DFT and Prony methods to sliding windows. This method does not suffer problems of spectral leakage and guarantees a significant reduction of computational efforts compared with the application of the only Prony method. Experiments are conducted and comparisons are made with traditional methods using both synthetic and measured waveforms. The results confirm the effectiveness and efficiency of the proposed scheme.