Recognition of Voltage Sag Disturbance by Mamdani Fuzzy Inference

A classification method of detecting the voltage sag sources based on Mamdani fuzzy inference is introduced in this paper. Three main sag reasons of short-faults, transformers energizing and large-capacity induction motor starting are analyzed. There are some different phenomena during the voltage sags caused by different sources. The characters of the balanced of the three phases, the changing trend of the voltage when the sag ends and voltage harmonic ratio during the sag are considered to be the criteria of recognizing the different voltage sag sources by using Mamdani fuzzy inference. Mamdani fuzzy inference uses the rules which are already known to carry out the reasoning computations from input to output. The correction of this method is proved by some simulations taken in the paper.