Research And Simulation Of Three Level Active Power Filter

The demand for power supply network in modern industrial production and daily life is not only "quantity",but also "quality".There are relevant standards for the quality requirements of the power supply network,in which harmonics are an important standard to judge the "cleanliness" of power supply.Active filter(APF)is an electrical equipment designed to filter out harmonics in the power grid.This paper studies the three-level APF based on the neutral point clamping(NPC)topological structure.The control system of the three-level APF uses double closed-loop control mode.The voltage outer loop is used to control the DC side capacitor smooth charging and voltage stability during start-up,while the current inner loop is mainly used to track the current signal.The main work of this paper is as follows:1.This paper briefly analyzes the working principle of the active filter,deduces the mathematical model,introduces the SVPWM modulation strategy in the60 °coordinate system,improves the harmonic detection link of the active filter.The DSOGI-PLL phase-locked loop is used to improve the performance of the harmonic detection link and reduce the harmonic content in the fundamental wave extracted by the load current.2.The voltage controller of the voltage outer loop is changed from the PI controller to the fuzzy PI controller to reduce the impulse voltage and current during the start-up phase of the APF.The current controller of the current inner loop is no longer controlled by PI,but is replaced by quasi-PR control to improve the current tracking effect of the current loop.3.In this paper,several models for all the changes in APF are built to verify the effect before and after the improvement.Finally,a comprehensive model for three improvements is built to verify the performance of the three improvements in the same model.And external interference is simulated to test the performance of the APF mode.Figure [61] table [9] reference [65]...