Analysis And Experiment Research On Measurement Accuracy Influencing Factors Of Power Quality

In the future, the smart grid required to high power quality. But in the contemporary, the type and characteristics of the power source as well as the grid structure and loads are undergoing profound changes. A variety of power electronic devices and non-linear equipments switch in power system, which have had a serious impact on the power quality. In addition, the sensitive loads to power quality is increasing, such as the computer, automatic production lines, programmable controllers. So the power quality of the grid has become the important issues to be concerned. And so the power quality measurement and monitor is more important. It is a prerequisite to carry out other work and the measurement accuracy is the key to evaluate the power quality. Therefore we need study the power quality measurement accuracy.The whole measurement chain contains the following three parts:transducers, measurement unit and evaluation unit. It refers to potential transformer, current transformer and power quality analyzer. The power quality measurement accuracy will research according to the former respects in this article.As to test and calibrate the power quality analyzer, there was the system which can test the basic power quality parameters and the FFT window width of voltage harmonic. And in this issue a method has been proposed to detect the harmonic measurement aggregation algorithm. In addition, a calibration system is designed.Base on the above test, considering the actual need, the error of the data using gap harmonic measurement have been analyzed by MATLAB. Moreover it needs to test the voltage RMS aggregation algorithm and the influence of power system influence quantities on each measured parameter.Also the transducers accuracy should be considered in power quality measurement, because the power quality analyzers are generally provided with inputs designed for low-voltage applications. This issue just analysis the harmonic transfer characteristics of the current transformer, especially the low-frequency inter-harmonic. The simulation experiment is carried out by PSCAD.