Research On Three-phase Four-switch Active Power Filter For Grid-side Current Detection

With the rapid development of power electronics technology,its negative effects as non-linear and time-varying loads have become increasingly obvious,and the switching action of power electronics devices has gradually become the main harmonic source.Active Power Filter(APF)is a new type of power electronic device which can dynamically detect and compensate harmonic currents in power grid.It has good real-time compensation,fast dynamic response and is not easy to resonate with power grid,so it has been widely studied.The research of APF is mostly focused on the basic principle and theory of APF,and is mainly based on three-phase six-switch topology.Inverters are in high-frequency on-off state for a long time and are prone to failure.Therefore,it is particularly important to improve the compensation performance of three-phase four-switch APF after fault.On the basis of reading a lot of relevant literature at home and abroad,this dissertation makes a detailed analysis of the development prospects of APF through the understanding of the current research situation of APF,and discusses the importance of three-phase four-switch active power filter in fault-tolerant field and small and medium capacity field in low-voltage power system.The active power filter system designed in this paper adopts grid-side current control strategy,eliminates the link of load current detection,saves a set of current sensors,and avoids the errors caused by load current detection.After the disadvantage of traditional PI control algorithm in controlling AC output,the Proportional IntegralVector Proportional Integral(PI-VPI)control algorithm is adopted to improve the compensation accuracy.Then this dissertation analyses the influence of DC voltage on AC output from the energy point of view,and formulates the corresponding voltage stabilization and equalization strategy.After analyzing the utilization ratio of DC voltage in three-phase four-switch APF,the space vector pulse width modulation(SVPWM)strategy is adopted.Finally,according to the parameters of the key components calculated theoretically,the overall model of three-phase four-switch active power filter is built by using MATLAB software,and the design scheme of this paper is verified.On the basis of theoretical analysis and simulation verification,an experimental platform is built.The simulation and experimental results verify the correctness and effectiveness of the scheme.