Coordinated Control Of Power Factor And Harmonic At Grid Side Of Motor Speed Regulation System

As an important part of modern industry,motor system plays an important role in national pillar industry and basic livelihood guarantee.Motor AC variable frequency speed regulation system has been widely used and popularized in the industrial field because of its high reliability,good regulation performance,stability and energy saving.However,the introduction of frequency conversion may affect the harmonics and power factor at the power grid side and cause pollution at the power grid side.Therefore,the coordinated control of harmonic and power factor at the grid side of motor speed regulation system has important theoretical and engineering significance for improving the operation efficiency and stability of power system.First,the background and importance of the topic is introduced,the status of the investigation is discussed.And discusses the development trends at home and abroad from the three aspects of network side PWM rectifier topology,PWM rectifier control strategy and Dual PWM rectifier control strategy,and summarizes the topology and control methods used in the existing motor speed regulation system.Then,the basic topology of AC variable frequency speed regulation system,vector control method and the performance of variable frequency speed regulation system are studied and analyzed.The system structure and the function of each part of the circuit topology in the system are clarified.Based on the principle of vector control,the frequency conversion speed regulation control method of the system is introduced.The influence of diode rectifier on system performance is analyzed.The simulation of MATLAB / Simulink shows that this method can realize the rapid and accurate control of speed,but there are still some problems such as sudden rise of voltage in braking state and poor performance of grid side.Then,aiming at the limitations of the existing motor speed regulation system,the research of four quadrant AC motor speed regulation system based on PWM rectifier is carried out.The mathematical model and control principle of PWM rectifier are analyzed.The rectifier control method based on state feedforward structure is designed,and the PI parameter setting principle of current regulator and voltage regulator under decoupling condition is determined.The simulation results show that the dual PWM converter is better than the traditional uncontrolled rectifier converter in operation efficiency and power grid characteristics.Finally,for the harmonic and reactive current problems caused by nonlinear load,the research on reactive power and harmonic control of distribution network in multi motor system is carried out.This paper introduces the structure of multi motor system,and focuses on the principle of PWM rectifier as reactive power compensation and filtering.The control scheme of rectifier system based on harmonic compensation in rotating coordinate and the detection scheme of power grid harmonic current based on rotating coordinate are designed.The MATLAB / Simulink simulation model of multi motor speed regulation system based on public rectifier system is established,and the characteristics of multi motor speed regulation system of public rectifier system under multiple working conditions are studied.The simulation results show that the enterprise power grid with public rectifier system has good quality value.