Comparison of Windowed Fourier Transform and dynamic phasors for Power Quality Analysis

This paper presents the use of digital signal processing techniques in Power Quality Analysis. This involved the use of Windowed Fourier Transform (WFT) to develop modified indices that would account for adverse effects of components in the system. The use of the Walsh Transform for Power Quality assessment of power electronic operation is also discussed. Some characteristics of the Walsh series make them ideal to represent switching functions. A third method, Dynamic Phasors was also considered to implement an index that describes phenomena with slowly varying spectrum. The results show that we can use the Windowed Fourier Transform in the calculations of STHD index in different moments of the signal with different window widths. The results also show the convenience of using Dynamic Phasors to study the different harmonics components of a signal and how to use this tool in Power Quality Analysis.