Sliding window recursive DFT with dyadic downsampling — A new strategy for time-varying power harmonic decomposition

The main objective of this paper is to present a time-varying harmonic decomposition using the sliding-window Discrete Fourier Transform including a dyadic downsampling. The method has been conceived to decompose and to visualize time-varying harmonics up to 15^th order, with a low computational effort. The downsampling must be done carefully in order to impose no aliasing error to the lower order harmonics. The algorithm has been very efficient and helpful when tracking time-varying power harmonic and it has been applied to track harmonic distortion and understand time-dependent power quality events. The method presents potential for other applications such as control and protection.