Research On Harmonic Restraining Technology Based On Active Power Filter

With the wide application of nonlinear loads, the amount of harmonic current has been increasing, which causes the labefaction of power quality. The active power filter (APF) with its predominant compensate performance, has been a hot research spot in power electronics area. The harmonic current detecting and current tracking controlling are systemically researched in this dissertation.Firstly, this dissertation extends the detecting method based on the instantaneous reactive power theory used in three-phase three-wire circuits, and presents new harmonic and reactive current detecting methods based on this theory respectively, which can be used in three-phase four-wire circuits and single-phase circuits. Secondly, contraposes the limitation of the traditional harmonic current detecting method based on neural network, presents the method that combines the neural network and auto adaptive harmonic current detecting method based on the principle of noise each other eliminating.As the characteristics that are small calculative quantity, fast converge, without local minimal point of Redial Basis Function (RBF), this dissertation forms a new harmonic current detecting method based on RBF. The simulation results show that the method has many advantages, such as good dynamic response, high accuracy and adaptability to mutative load currents. Thirdly, a control calculation method based on fixed DSP is deduced basing on deeply analyzing theory of Space Vector Control in this dissertation. Simulation models of shunt active power filter system based on this method are built in environment of MATLAB software. The simulation results show that this control arithmetic is superior to traditional control method, it can not only eliminate harmonic current effectively, but also has better dynamatic compensation characteristic, and can improve the improve the integral performance of the active power filter effectively.At last, base on the theory and simulation, this dissertation designs control system and main circuit parameter of shut APF, and the circuits of hardware interface and signal sampling are manufactured and tested.