Study On DC Side Series Active Power Filter Based On One-cycle Control

With the large number of rectifying devices, such as non-linear load used in power grid, which brought the harmonic pollution, has increasingly become affected the power system security and power quality. Direct current (DC) side active power filter (APF) is a novel harmonic suppression device, which has advantages for a simple circuit structure and low cost. Thus it has great technological advantages for managing the harmonics of the rectification load and at present the study has been mainly concentrated in the parallel APF. However, the system load impedance has greater impact on parallel APF so it's compensation results are not satisfactory, especially for voltage type harmonic sources, taken up a great proportion in rectifier load. Series APF is to overcome this shortcoming and has better performance. In addition, one-cycle control technique as a general non-linear control, which was the first used for control of APF since 2000, is widely concerned on its unique advantages. At present, the research of APF based on one-cycle control, is also mainly concentrated in the parallel APF, for the research of series APF based on one-cycle control study is very small, and the research of DC side series APF based on one-cycle control has not yet started.For this issue, the one-cycle control is introduced to DC side series APF, to fills the research gaps in this area; the one-cycle control is applied to three-phase DC side series APF, to expand its scope of application; an improved topology structure of the DC side series APF is propose under the deep study of original structure DC side series APF.In this thesis, the basic principle of one-cycle control is described firstly, and the switch circuit based on one-cycle control is modeled and its switch control theory is analyzed deeply. Some improved one-cycle control methods for APF and the wider application of APF based on one-cycle control are comprehensively discussed.Subsequently, the one-cycle control is introduced to DC side series APF. On the basis of analyzing its main circuit principle, the control equation with one-cycle control of DC side series APF is derived, the DC side series APF with one-cycle control is modeled, the selection criteria for parameters of main circuit and regulator are designed, and simulation in-depth of the APF is given.Based on the molded current type and voltage type harmonic sources, in this thesis, different compensation characteristics of harmonic sources to parallel and series APF are discussed, and the simulation comparison research of DC side series APF and parallel are given. Based on the establishment of unified model both DC and AC side series APF, both calculation formulas of compensation capacity and switch utilization ratio are derived, and their comparison research of compensation capacity and switch utilization ratio are given too.Due to plenty use of three-phase uncontrolled rectifiers, the three-phase DC side series APF based on one-cycle control is proposed. In a detailed analysis of its working principle, the control relations are derived, the control model of three-phase three-wire DC side series APF with one-cycle control is set up, and the simulation research of three-phase DC side series APF is given.Finally, this thesis is based on the deep research of inherent constraints between output and input voltages of DC side series APF, and it points out the regulation shortage of output voltage about original circuit structure with high output voltage. An improved topology structure of DC side series APF is proposed, its working principles are detailed, and simulation research has been verified.