Comprehensive Evaluation Of Power Quality Considering Customers’Demands

Power quality becomes increasingly significant toward power users as the economy has amazingly developed and the high-technology-facilities were expanded largely. Under the circumstance of electricity market, different customers have different requirements to power quality because of their demands. In this situation, not only the requirements of power grid but also the customers’ demands should be considered when we comprehensively evaluate the power quality.Firstly, the definition and characteristic of power quality are introduced, and then the index of power quality is classified and calculated also in this paper. Based on the above, the synthetic evaluation methods, such as method based on fuzzy mathematics, probability and mathematical statistics and vector algebra method, intelligent algorithm, etc. are classified and compared with each other.And then, a novel power quality comprehensively evaluation method considering customers’ demand is proposed. Triangular fuzzy number is used to quantitate the customers’ linguistic information. Take the relative consistency indicators of customers as their weight, and then the of triangular fuzzy number is used to joint the groups’ information which not only considers the groups’ opinion but also put forward the multi-objective problem changing into single objective problem. Based on this, the topsis method is used to determine the power quality grades of all monitoring points. Simulation results verify the effectiveness of the proposed method.Further more, a novel power quality comprehensively evaluation method considering consumer demand and expert is proposed. Firstly, the evaluations on advantages or disadvantages of indices of all monitoring points are described by language evaluation and expert grading respectively; then taking evaluation information as the evidence, the evidence synthesis is performed by Dempster-Shafer theory to determine the evaluation information on each monitoring point from consumers and experts and to determine the weight of individual, the conflict degree is used to calculate the weight of individual by which the weight of each individual is updated, meanwhile the weights of different groups are taken into account; finally the Dempster-Shafer theory is used again to determine the power quality grades of all monitoring points. The proposed method not only can incarnate different requirements of consumers for power quality, but also can reflect experts’ knowledge, so it can incarnate the evaluation opinions of the majority. Simulation results verify the effectiveness of the proposed method.