The Study On Deteetion Methods Base On SPLL Of Unite Power Ouality Conditioner

With the development of modern science and technology, the problems of power qualityhave been greatly concerned. Unified Power Quality Conditioner (UPQC)can compensate theload reactive current and harmonic current, also can suppress voltage fluctuations, voltage flickerand imbalance voltage of each phase, it can provide users with high-quality power, so it is apowerful tool to solve power quality problems. So as a solution device to most of the powerquality, UPQC has become a hot area in researching of power quality problems.Firstly, this article describes the grid power quality problems and hazards. Then describesthe development and current status of the Unified Power Quality Conditioner briefly, And on thisbasis, the article analyzes the topology and compensation principle of the UPQC. To the decisiveinfluences of UPQC compensation-detection and control methods, the article makes detailedstudying and discussion. In detective methods, describing and comparing a variety of detectivealgorithms firstly, and focusing on the instantaneous reactive power theory in detail, based onthese, Combining with the ideal of UPQC compensation, deriving a unity voltage and currentdetective algorithm based on the UPQC dq0transformation, in this algorithm，introducing amore accurate software phase-locked loop (SPLL),to provide accurate synchronization signal,and voltage detection part has been improved to simplify the complexity of the detection part andreduced the computational. Simulation studies have been made to verify its validity. In thecontrol method, the hysteresis control was introduced, for the shortcomings of this algorithm,constant frequency hysteresis control was introduced, and made a detailed theoretical analysis.While the one-cycle control is described, and made a simulation for the two algorithms. Finally,according to the test aspects of the design algorithm used in the corresponding, hardware circuitfor voltage and current harmonics is made, and the results prove that the method is correct.