Development Of Shunt Three-level APF In Rural Power Grid Distribution Area

Under the background of continuous renewal of theoretical physics and applied technologies and rapid development,power electronic devices are increasingly used in modern industrial production and life.However,some non-linear problems appearing in the power electronics device work link have caused the power quality at the current stage to be seriously affected,which in turn has led to a drop in power quality.The decline in power supply quality not only has a serious impact on the production and livelihood of cities with high electricity demand and high demand for electricity safety.At the same time,as the national strength increases and the economy soars,the decline in power supply quality also significantly improves the quality of life.The majority of rural areas have no small impact and cause electricity hazards.Therefore,this article focuses on improving the power quality of rural power grid distribution stations and discussing the prevention of harmonic pollution.Current research has found that active power filters can effectively solve this problem.It can continuously compensate for harmonics and reactive power,and govern power quality.Therefore,this study uses a parallel three-level active power filter(Active Power Filter,APF)as a research direction,and from the harmonic detection method,harmonic current tracking control,three-phase three-wire parallel LCL three-level APF's system simulation and its hardware and software design were studied.The main contents are as follows:Firstly,the definition of power quality,the causes of harmonic generation,and the hazards are introduced.The current research status of APF is described in detail,and the key technologies of APF:harmonic current detection technology and harmonic current tracking technology are elaborated.List analysis.Secondly,the relevant theory of active power filter currently mastered is introduced,and the detailed theoretical introduction and rigorous formula derivation of the topological structure,mathematical model and switching function of three-phase three-wire parallel LCL three-level APF are introduced.Then the mathematical model and switching function of the three-level APF are analyzed in abc coordinate system and dq coordinate system.On this basis,this article also introduces and analyzes harmonic current detection method based on instantaneous reactive power and its derived p-q detection method i_p-i_q detection method,and uses i_p-i_q detection method as harmonic current detection of this experiment.method.Next,the current tracking control method of APF is analyzed,and an improved simplified algorithm that is different from the traditional three-level Space Vector Pulse-Width Modulation(SVPWM)method is introduced.The method is based on space vectors and formulas.Derivation,detailed comparison elaborated the difference between the traditional SVPWM modulation strategy and the improved SVPWM modulation strategy.In the end,this paper analyzes the current harmonic detection method and tracking control method of the three-level APF,and uses the Matlab/Simulink platform to build a simulation model.The i_p-i_q harmonic detection is verified by the simulation experiment waveform and spectrum results.Technology and effectiveness of the improved SVPWM modulation strategy.Then the hardware was designed and the whole hardware was divided into three parts:sample conditioning circuit,power supply circuit,and driver circuit.Then the software flow was designed for the designed hardware circuit.Finally,the experimental platform was built and the experimental research was completed.Simulation and experimental results all can demonstrate the effectiveness and practical feasibility of this control method in this paper.