The Study Of Active Power Filter Under Nonideal Power Grid

In order to improve the power quality,the active power filter(APF)has been deeply studied.However,the research on the key technologies of APF at home and abroad is based on the ideal power grid.In fact,the power grid is not always maintained in a stable state,and imbalance and distortion condition of the power grid voltage will also occur.Therefore,this paper studies the key technology of APF under the condition of non-ideal.This paper introduces the research status of APF,describes the working principle of APF and classifies it according to the different topology of its main circuit.The mathematical modeling of a single inductor filter parallel APF is set up.The advantages and disadvantages of several ideal and non-ideal grid voltage phase-locked methods are analyzed,and a specific sub-harmonic filter phase locking is proposed.Several common harmonic detection algorithms are introduced.In order to compensate the various components of the load current flexibly under the condition of the non-ideal power grid,a harmonic detection algorithm based on the CPT theory is proposed.The repetitive control is applied to the current loop and the PI controller is connected in series with it to form the current loop control strategy of the APF.The repetitive control is improved and the repetitive control focusing on dynamic performance is proposed.This paper analyzes the disturbance caused by non-ideal grid voltage to the DC side voltage of APF,the disturbance caused by harmonic current generated by nonlinear load to the DC side voltage.And the voltage loop is improved as well.To verify the correctness of the APF's key technology theory,a simulation platform is built in Matlab/Simulink,and nonlinear load currents are compensated for nonlinear load currents under normal and abnormal power grid conditions.At the same time,the hardware design and digital program is designed on the basis of simulation parameters.An experimental platform with capacity of 10kVA is built to verify the feasibility of the key technology.