Study On Parallel Hybrid Active Power Filter

Accounted for the phenomenon that the nonlinear loads of power system generateharmonic pollution and the incapacity of the harmonic compensation with the Active PowerFilter (APF) alone, the present thesis mainly study on the Hybrid Active Power Filter (HAPF)based on the Passive Filter (PF) and APF. According to the detail analysis of the HAPF’sstructure and working principle, the relevant mathematics model is constructed.The thesis mainly focuses on the control strategy of the adopted HAPF. Firstly, theequivalent circuit mode of HAPF under a composite control is analyzed in the paper aiming toprovide a reference for the selection of the parameter in stable system. Secondly, in order toreduce the computation delay caused by Low Pass Filter (LPF) in traditional p-q and i_p-i_qharmonic current detection method, a novel mean filter which can raise computation speed isdesigned to replace the LPF. Then, a Fuzzy Logic variable bandwidth hysteresis currenttracking method is put out, based on the conflict between tracking precision and maximumswitching frequency of switching devices in traditional triangle wave comparison controlmethod and hysteresis current tracking method. Moreover, simulation models of this HAPFsystem were built by using Matlab7.1, with the aid of Simulink to construct simulationmodels of the whole system. The results of simulation showed the modified control strategycould motivate HAPF to eliminate harmonic current effectively, and equip the whole systemwith a better dynamic property.Finally, the system experiments devices of harmonic detection and compensation areconstructed, completing the Hardware circuit design and software design of this HAPFsystem. Hardware design mainly includes the calculation of the component parameters of PF,the design of the drive circuit, the selection of the output filter, the choice of couplingtransformer, the design of the protection circuit and DSP peripheral control circuit. Softwarepart includes the flow of the main program, interrupt program and the realization of theharmonic calculation method.