Research On Power Quality Analyzer

With the rapid development of science technology and national economy, diverse kinds of industry production demand higher power quality; moreover, with the widely application of modern power electronics technology, power quality is deteriorated increasingly; therefore, more and more close attention is paid to power quality by both electric department and consumers. Power as a kind of special merchandise, there is a tendency of its price scaled according to its quality. So detecting and analyzing power quality is very significant. In this paper, the theory on power quality detection is researched in great depth. On the basis of the theory, a power quality analyzer is designed and developed. Firstly, the theory and realization of every index of power quality are researched. Harmonic analysis and flicker are emphasized in our research. The theory of harmonic analysis and its measurement means (FFT) are introduced in detail. The problems in application are analyzed and the solving ways put forward. A discrete means to measure flicker is realized in DSP through simplifing the IEC's model of flicker measurement. Secondly, in chapter 3 and chapter 4, a power quality analyzer is designed and developed on the basis of the theories in chapter 2. In the aspect of hardware, this paper uses the digital signal processor (DSP) to speed up the algorithm, and introduces the CPLD to simplify the periphery logic circuit design. To decrease the error brought by non-synchronous sampling, this paper presents a way based on frequency pursuit to realize synchronous sampling by software. To avoid the phrase error engendered by the multi-channel non-simultaneous sampling, this paper uses a 16-bit, 6-channel simultaneous sampling analog-to-digital converters. In the aspect of software, this paper designs the system software on modularization principle. The interrupt distribution and the influences of interrupt to measure are introduced in detail. Main program flow chart is presented. The realization of synchronous sampling by software, harmonic analysis and flicker in DSP are also discussed. Then, the framework and test results of single-phase power quality analyzer are introduced. The results indicate that the measurement accuracy of elementary items is better than class 0.2 and harmonic analysis is correct, so it's a good basis to three phases system. The wireless communication design is also introduced in detail. The research is summarized in the end of this paper.