Research And Design Of Power Quality Monitoring System

Study project in the thesis is one of important parts of" The study of power quality monitering device " supported by the technology fund of The ShanXi Science and Technology Department, which is proposed to the increasingly complex power quality problems at present. The research of Power quality is an important part of the smart grid, which is an interdisciplinary and difficulty subject. Power quality monitoring has become an emerging technology, which are attached importance to overseas and domestic electric power personnels. In this thesis, based on the theory and measure of power quality, the power quality monitoring equipment is designed for current market demand.A details about four indicators of power quality which is affecting power quality problems greatly and analysis of the current situation and existing problems of power quality problems in the current power system has be introduced in this paper. Based on studying the definition and detection of the power quality index, this paper focuses on the fast Fourier algorithm (FFT). And found that using this method works for the application of harmonic detection, testing better. On the basis of the above theory, this paper began to design a power quality monitoring system, which contains three parts of the pre-monitoring unit, the test software and the management software.The pre-monitoring unit meets the requirements of the sampling system and has a sampling of high precision, fast processing, etc. And it provides a premise security for the measurement accuracy of the testing software.The testing software was achieved in two ways of front-end hardware testing and PC software testing. The front-end hardware detection program was researched in this paper firstly. The author analysis and implement front-end hardware detection program with the example of harmonic and three-phase unbalanced. Confined to the limitations of front-end hardware detection, the authors designed the PC software testing, whose program development platform used VS 2005 and implementation language chosen C#. Using PC software testing can greatly reduce program development time of the complete system and the burden on the hardware platform. At the same time, in order to make monitoring system more efficiency, the article adopts a upper computer software inspect program based on FFT, achieves the function of many indicator inspected by one arithmetic. In this program, FFT Algorithm can not only inspect harmonic wave precisely, but also extraction the base wave information for symmetrical component method, and inspect the frequency. On this basis, the author improved FFT program. The advantage of the program is the result of the FFT resolution is adjustable, in line with the increasing demands of the harmonic detection. The application results of the PC software testing are analyzed. And the results showed that the PC software testing has a good application, stability and accuracy.The system data management and the application management system were divided into two parts in the paper, when designing the management software program. Considering and analyzing the PQDIF special in this thesis, which is a standard data formats. And studying the application of PQDIF file can provide some reference for the future development of PQDIF technology.In the thesis, the theoretical and practical aspects of power quality were analyzed and applied. And the thesis has some significance on the study of power quality and the power quality monitoring market development.