Tracking power quality disturbance waveforms via adaptive linear combiners and fuzzy decision support systems

The paper presents the classification of power quality disturbances in power supply networks using a hybrid notch filter-linear combiner. The adaptive notch filter is used to provide the frequency estimate of the power supply network voltage signal, while the linear combiner computes the peak amplitude of the fundamental voltage with the total harmonic distortion factor, THD. The various power line disturbances like voltage sag, swell, outage, and surge, etc. are then classified using a fuzzy decision system using the fuzzified values of amplitude ad its rate of change of the peak fundamental voltage component. The distorted waveform is classified using the THD factor. Detailed digital simulation results for an AC system supplying nonlinear converter load via a transmission network and subjected to a variety of transient disturbances are presented to identify these disturbances.