Study On Power Quality Synthetic Evaluation Of Power Systems

With the advent of power quality contract, which is on behalf of the in-depth energy services, power quality synthetic evaluation has seen the dawn of its application. In this situation, our country also intends to develop standards of power quality evaluation(including synthetic evaluation). In this paper, evaluation indexes, evaluation methods, evaluation models of power quality synthetic evaluation and its application in the power grid were studied.In this paper, the existing system of power quality indexes was analyzed, and the power quality synthetic evaluation system was proposed, which includes the system of power quality indexes(voltage dips and short interruptions were included), statistical methods of indexes, selection methods of monitoring points and power quality synthetic evaluation methods. On the base of synthetic quantitative evaluation method and synthetic rating method, three ways of evaluation was proposed, which is vertical, horizontal and vertical and horizontal. By using the dual excitation control lines, dynamic synthetic evaluations of power quality in regional power grid was achieved.On this basis, this paper established a power quality synthetic quantitative evaluation model and a synthetic rating model based on interval number approximation. In weighting session, an improved entropy weight method was proposed, which fixes the problem of traditional entropy weight method that entropy weights present the wrong message of entropy when all the entropy values are close to one. Considering of power quality standards all of the world as well as special needs of some industries, this paper presented a synthetic classification method of power quality, and established a synthetic rating model based on interval number approximation, to simplify the evaluation results, and to enhance its practical value. With the power quality measurement data, the above models were analyzed and compared with each other, which verify the rationality and effectiveness of the proposed methods. This paper made a useful exploration for applications of power quality synthetic evaluation in energy trading and the improvement of power quality synthetic evaluation indexes.