Study On The Key Techniques Of Harmonic Detection And Control Strategy In Active Power Filter

The more and more power electronic devices and nonlinear loads make the power polluted. The harmonic can cause problems for power generation, power transmission and electric equipment. However the people demand on the higher power quality day by day. Therefore, improving power quality should be taken on urgency. As a dynamic equipment of harmonic compensation, active power filter has become research focus. This paper does an in-depth study on the main circuit parameters, adaptive harmonic detection algorithm, the software phase- locked loop and other aspects of the active power filter. The harmonic detection algorithm and the adopted control scheme are verified by simulation and experiments.First of all, the harm to the harmonic is analyzed. By consulting literature, the development of active power filter and its working principle are introduced. The main research direction in recent years are summarized, the different research direction are introduced. Then the research direction of this paper is determined based on the hotspot. The mathematical model of active power filter is established and the applications of the different coordinates are described. The main components of the circuit of active power filter are discussed through theoretical analysis and calculation. It provides theoretical support for building simulation and experiment platform.The existing adaptive harmonic detection algorithm can’t balance the accuracy and rapidity. The paper improves the existing adaptive algorithms according to the mathematical theory. The new algorithm makes iterative calculation using a dynamic step size with adaptive gain. The new algorithm has not only higher accuracy but also higher dynamic response. The simulation and DSP experiment verify the validity of the algorithm.Because of the disadvantages of the phase locked method on the previous platform, the principle and the realization method of software phase locked loop are studied. And performance is analyzed under three-phase unbalance and the voltage distortion conditions. This paper adopts the filter to filter the interference. The improved software phase- locked algorithm is proved by the simulation and the experiment. This paper adopts the control scheme based on dq rotating frame, which is introduced in detail. The space vector modulation algorithm commonly used in engineering is introduced. The hardware and software of the experiment are also designed. At last, the harmonic detection algorithm and control strategy adopted in this paper are verified on the APF system by simulation and experiment.