Research On Shunt Unit Of Asymmetric Unified Power Quality Conditioner

This dissertation is a part of the project of Flexible Alterative Current Distribution System which is belongs to Beijing Jiao tong University School Science and Technology Fund; this dissertation is focus on the study of shunt unit of Unified Power Quality Controller for three-phase four-line distribution power system.This dissertation first presents topological structure and working principle of Unified Power Quality Controller for three-phase four-line system, decomposes the function of series parts of parallel parts of Unified Power Quality Controller, and establishes mathematical model of part in parallel of Unified Power Quality Controller.This dissertation next researches the instantaneous reactive power theory of three-phase four-wire system and explains definition and meaning of transient active power, instantaneous reactive power. On the basis of that theory, this paper puts forward a kind of harmonic current detection methods which applicable for three-phase four-wire system , this method has a good real-time performance and easy to realize digitization.Due to neutral of three-phase four-wire system, so the main circuit and control circuit in the structure all have their own characteristics. Different compensation method of neutral current produces different structure forms of main circuit and control methods. This dissertation studies a structure - 4 in converter form, and put forward a corresponding control method.Under the condition of after solving real-time detection methods of the harmonic current and the working principle under the arm of four bridge circuit of the three-phase four-wire system, the authors develops parallel experiments equipment on the basis of the four converters in main circuit. In the end, the thesis introduces the circuit principle for the system, the design of the main circuit, calculation of the main components parameters in detail.