Research On Current Track Strategy Of Modular Three-level Active Power Filter

With the large number of nonlinear loads in the grid applications,harmonic pollution problem has become a serious problem affecting the quality of the power grid system.Active power filter(APF)is one of the main means to solve the grid harmonic pollution,especially the three-level active power filter,with small current ripple,low harmonic distortion,compact hardware structure,easy module design,etc.,has been widely studied and applied.In the study of active power filter control algorithm,the current loop tracking control strategy is the most critical and central part,this paper,combined with simulation and experiment,has a research on current track strategy of modular three-level active power filter.This paper describes the basic structure and working principle of the three-level shunt APF,states its control method,and focuses on research of the current loop tracking control strategy which is the most critical factor in harmonic compensation effect.This paper focuses on the analysis of proportional integral controller,proportional resonant controller and repetitive controller,including the basic principles,parameter design,system stability,and the specific application in APF,etc.,and proposes the current loop control schemes of proportional resonant control and PI + repetitive control in abc three-phase static coordinate system and dq synchronous rotating coordinate system.In this paper,each control scheme is verified and compared through Matlab / Simulink simulation platform,and reasonable results have been obtained.At the same,a modular three-level active power filter prototype based on DSP28335 + CPLD is built,in which the rated compensation current is 50 A.This paper tests the current loop control schemes of proportional resonant control and PI + repetitive control in abc three-phase static coordinate system and dq synchronous rotating coordinate system by using the prototype,verifies the feasibility of the relevant control strategies,and compares and analysis their steady performance and dynamic performance.