Hybrid Algorithms for Denoising Electrical Waveforms Containing Steady Segments

Comparative study of wavelet based techniques for electromagnetic noise evaluation and removal

“…An original adaptation of the average signal technique was conceived by the authors and presented in [7]. It allows for the determination of the signals quasi-stationary segments and evaluation of the noise polluting them.…”

“…Sets of three-phase currents as those from Fig. 1 were analyzed [7]. The waveforms were acquired with a sampling rate of 700 samples per period.…”

“…Fig. 3 represents the signals obtained as difference (polluted minus ASs), called estimated noises for a signal analyzed in [7]. The rectangle was used to emphasize a subinterval exhibiting a normal behavior of noise.…”

“…3 metrics were computed for all subintervals: (a) noises powers; (b) averages of noises (AVS mean noises); (c) standard deviations (SD) of the absolute values of local peaks exhibited by the estimated noises. SD-s were computed considering the formula [7]:…”

“…A correct denoising allows for a more accurate evaluation of power quality indices and detection of faults by using wavelet based decompositions [3]. When the analyzed data have a quasi-stationary nature and are polluted by white noise, a special technique (relying on average signals) can be applied [4]... [7]. According to it, repetitive additions of noisy signals tend to emphasize their systematic characteristics and to cancel out any zero-mean random noise.…”