The Research On Hybrid Active Power Filter

Active power filters (APF) are widely used to reduce harmonics, compensate the reactive power, and improve the power factor due to its advantages of superior controllability, fast responding, small bulk and weight, and its achievements are more and more. But the cost of APF is expensive, so this disadvantage restricts the practical application. Combined active power filter and reactive power filter make up hybrid active power filter which not only reduce the cost but also have good harmonics compensation effect, so hybrid active power filter reaches a practical purpose.The paper introduces the concept of harmonics,its harm to power grid and limitation of harmonics voltage and current harmonics , and it also demonstrates the necessity of eliminate harmonics, and briefly introduces several methods to eliminate harmonics and research of both here and abroad. The paper analyzes respective principles and relative merits of passive filter, active power filter and hybrid active power filter. Then the paper detailedly introduces the theory of instantaneous reactive power,the adaptive harmonic detecting algorithm and the way of harmonic currents of a single-phase. On the base of former predicting of the harmonic currents, the paper proposes a novel predicting of the harmonic currents which can predict the deviation of t+2 moment at the moment, and simulates the every kind of harmonics detection methods by MATLAB/simulink. Then the paper analyzes control system of hybrid active power filter,the way of harmonic detecting and the principle of control system, digital low pass filter and the generation of PWM, on the base of which the paper designs a new parallel hybrid active power filter which is controlled by TMS320LF2407, and detailedly introduces drive circuit of PWM, sampling circuit of current, voltage adjustment and protection circuit, communication circuit, liquid crystal display circuit. In the end the paper simulates hardware systems and harmonics detection methods by MATLAB/simulink. The simulation and primarily experimental results verify the validity and feasibility of the method.