Research Of Power Quality Judgment Method

With the advance of society and science technology, more and more electronic devices and nonlinear devices have been used, leading to serious distortion of voltage and frequency in distribution network, that is power quality to be destroyed. Therefore, it is meaningful to research judgment method of power quality to power consumer.First of all, the thesis studies outline, national standard of power quality, as well as research judgment method status of power quality at home and abroad in detail. Through the introduction and statement of researching background of power quality, and the description of the problem caused by power quality damage, thesis draws a conclusion that is the importance of power quality judgingSecondly, the thesis has given the detailed description of smart meters with the advanced technology of General Packet Radio Service and public wireless communication network and the process of data remote collection about some distribution network, as well as the process of data analysis and diagram. The data what is measured is on the basis of two judgment methods as follows.Thirdly, aiming at the uncertain relationship among all the indicators of power quality, the thesis comes up with a fuzzy algorithm based on the trapezoidal membership function for power quality comprehensive rating. Membership degree and membership degree set come from the fuzzification of each one of individual judgment indicators. With the guidance of thought of Close-degree, the power quality on the Monitoring points is judged synthetically. Consequently, the rank of power equality revealed. According to experiment research, this technique can be utilized for judgment for the rank of power quality as a scientific and intuitionistic method.Finally, on the basis of the introduction of basic knowledge of power quality every indicator, the thesis puts forward a comprehensive judgment method based on Cask principle. First, power quality individual indicators are made into quantization and normalization, and reach the comprehensive index IG. Second, the essay set up comprehensive grade judgment model. And two methods are given, one is monitoring point comprehensive judgment method, the other one is system comprehensive judgment method. Last, according to the grade of each index, the essay has the final grade of power quality. Combining with the practical situation of the power quality of distribution network, the methods and measures have been put forward to improve the power quality.Based on actual monitored data, essay gives the practical example analysis. It turns out that the two methods which are Fuzzy algorithm and Cask principle of power quality comprehensive judgment what is proposed can achieve the power quality comprehensive considerations simply and effectively.