改进型UPQC拓扑结构及控制策略研究-电力电子与电力传动专业论文.docxVIP

ABSTRACT Wi由 the continuous increase of nonlinear loads in various types of power grid， power quality gets deteriorated continuously，so that it seriously endangers the security of power system and the interests of users. Conventional power quality compensation devices can not meet the increasing requirements to power quality of 噜 users. Unified Power Quality Conditioner (UPQC) as an integrated power quality compensator，not only can compensate the current quality problems of harmonic and 啕 reactive current caused by loads，but also can compensate the voltage problems of voltage swell，s吨， asymmetry，f1icker and fluctuation. UPQC is a new trend of consumer power technology. ηle current studies about UPQC mainly include topologies，operation principles， detection methods and control strategies. A lot of researches of control methods and control strategies about UPQC have been made before in our laboratory，and there are some achievements. This paper not only summarizes the preliminary work， but also makes some in-depth researches about different topologies. Taking the three-phase three-wire UPQC as the object and using super capacitor as 由e ener即， storage unit of the UPQCs DC side，this paper designed an improved UPQC topology. Making full use of super capacitors large energy storage capabiIity，this topology can well compens仰 a long time voltage drop or rising and short time interruptions. ηlis paper sets the improved UPQC as the study object， to analyze the system structure，functions and working principles. Meanwhile ，mathematical model of series and parallel converter and the DC ener.部， storage unit is established，and the power flow characteristics are also analyses deepl弘 Fundamental positive sequence component extraction method based on Synchronous coordinate transformation is used as the amount of compensation detecting method，and the corresponding improvement was carried out. The impact between series and