Research On A Hybrid Active Power Filter

High-quality and stable Power supply is the premise to maintain basic life and promote the development of production.Harmonics and reactive Power exceed the standard will bring serious harm to the Power system.Active Power Filter(APF)can control the harmonics of the Power grid.In the traditional APF,the active part often bears high fundamental voltage,which makes the system capacity too large.In order to solve this problem,a Hybrid Active Power Filter(HAPF)is proposed.HAPF can effectively reduce the fundamental Power of the Active part and compensate a certain amount of reactive Power by using the characteristics of the passive Filter,which has good filtering characteristics and high compensation accuracy.HAPF is an effective measure to reduce APF capacity and improve power quality.First of all,this paper expounds the basic theory of reactive power and harmonics,explains the harm it brings,and introduces the research status of harmonics and reactive power control at home and abroad.The advantages and disadvantages of various APF topologies are analyzed and compared.From the point of reducing the system capacity,a kind of HAPF is chosen for systematic research.Based on the main topological circuit of HAPF,its working principle and filtering characteristics are analyzed,and its mathematical models are established in different coordinate systems.Combined with the practical engineering application background,the principle of selecting the main circuit components and the basis of setting system parameters are discussed.Through the principle of partial voltage and shunt of passive LC single-tuned circuit,the fundamental power borne by active part can be effectively reduced,thus reducing the capacity of the whole system.Based on the mathematical model,the control strategy of the system is proposed,which can control the specified sub-harmonic current and the DC side voltage independently in the synchronous rotating coordinate system.By introducing grid voltage feedforward method,the DC voltage control is relatively stable,and the fundamental reactive current flowing through the converter is effectively reduced.In order to solve the resonant problem of the HAPF circuit,the state variable feedback method is adopted to introduce system damping to suppress the resonance of the system.According to the selected control strategy,the simulation model of the whole system is built in the MATLAB environment.Finally,based on the above analysis and research,a low-voltage experimental platform of HAPF hardware is built.DSP chip is used as the main controller,the peripheral circuit of each module is designed,the software code is written,and the functional indexes are tested and analyzed.Simulation and experimental results verify the validity of the theoretical analysis in this paper.