Research On Key Technologies Of Three-phase Three-wire Active Power Filter

Currently, the active power filter has become a mainstream power quality adjustment device. The development of shunt active power filter is most mature than other kinds of active power filter, and it has been widely applied into various power quality adjustment occasions. The object of this paper is study the application of the three-phase three-wire system shunt active power filter. This paper mainly discusses the mainstream control tactics and practical technologies.The output current of main circuit contain switching ripple and is filtered by switching ripple filter. Two promising LCL filters are compared with the LCL filter in the case of the damping resistor losses and the filter attenuation. A new design procedure which is based on iterative algorithms proposed for the promising LCL filter.The mathematical model of the three-phase three-wire shunt active power filter filter is established, and the loop of the current tracking control is designed on its basis of the model. A new control strategy that based on PI controller parallel connection with quasi-resonant controller is proposed. The simulation and experimental results show: The control strategy can precisely track the selected harmonic, and do not influenced by the stable DC bus voltage loop.When multi-level topology is selected as the main circuit DC bus voltage balancing control has to be designed. The underlying causes of DC bus voltage unbalancing are analyzed. An improved redundant small vectors method be proposed, which is improved the redundant vector selection and action time calculation. This method can reduce the fluctuation of the deviation between Positive and negative bus voltage.Harmonic current detection focuses on analyzing and comparing FFT method and IP-IQ method. Different FFT window interpolation algorithm be compared, and the Blackman-harris window can reduce the impact of Spectrum leakage and fences effect. The detection accuracy is analysed beween FFT method and ip-iq method, when the grid frequency is fluctuating.The experimental results show the design of this paper is reasonable and can provide some guidance for the utility of three-phase three-wire shunt active power filter.