A Fuzzy Approach for Power Quality Standards

The paper presents a fuzzy approach for harmonic voltage level based on the linguistic prescription of power quality standard. Harmonic currents are mainly generated by industrial and residential loads with non-linear characteristics. Industrial loads which are a source of significant levels of harmonic distortion include power converters, variable speed drives, induction furnaces, arc furnaces. Some types of electrical equipment are more sensitive to deviations from the sinusoidal supply voltage. The perturbation limits are imposed by several power quality standards. The values specified by these are not always the same, moreover, certain standards presents even linguistic formulations which are easy interpretable. Fuzzy sets and the membership functions related represent a useful instrument to approach such interpretations. In this context, the paper presents a fuzzy approach for power quality standards. The input variables are represented by harmonic voltages, and the output variable is the Total Harmonic Voltage Distortion (THD). The membership functions for the input and output variables were implemented in MatLab.