Fuzzy studies on power quality. I. Index and evaluation

Power quality has the chance to be fuzzy studied. This paper focuses on its index and evaluation. It first indicates a fuzzy measurement concept based on the consideration of the deviation from rated value. From this basic concept it takes the membership for fuzzy property of quality indices. Then the paper gives some representations for indices by different approaches to the membership. So the membership of a detailed quality can be its evaluation simply. Then in order to discuss the further fuzzy evaluation of power quality, the paper makes applications both on item quality and general quality. The former is using fuzzy comprehensive evaluation and the latter is multigrade advanced evaluation. For enhancing the accuracy of evaluation, the paper also makes some improvements on the fuzzy comprehensive evaluation. From the application case, it is not difficult to see that the paper realizes an effective evaluation of power quality, especially on general quality. So the fuzzy representations can also be successful for power quality studies.