Multi-level fuzzy comprehensive evaluation of power quality

Power quality (PQ) has assumed great importance in the past years in electrical system operation. Evaluation of PQ has become more and more crucial, especially when other PQ technologies have achieved great improvement. A multi-level fuzzy comprehensive evaluation algorithm is proposed to evaluate PQ. The PQ standards of China are referenced and key factors that influence PQ are extracted. These factors are divided into two levels to assess PQ. By constructing membership functions for all the factors separately according to their characteristics and by determining the weights of each factor using improved analytic hierarchy process (AHP), a model which can classify PQ into five grades is designed. At the end of the paper, the effectiveness of this approach is proved reasonable by computing some illustrative examples.