Research On The Control Of Microgrid Inverter Based On PQ Control

As fossil fuels are non-renewable energy sources,uncontrolled use and consumption of fossil fuels make human beings gradually face serious problems of exhausting energy.Countries around the world have begun to pay attention to the use of new energy sources,such as environmental protection,efficient distributed generation,solar power generation and so on.However,due to the uncontrollability of distributed generation,the development of microgrid is proposed.Microgrid can form a controllable independent power supply system by integrating distributed generation units.Therefore,the research on the operation and control of microgrid has a very good role in promoting the development and application of microgrid technology.The microgrid related technologies,from the micro power supply grid-connected control to the microgrid integrated operation,are studied in this paper.The main work includes:This paper introduces the composition and working principle of the micro-grid system,and mainly studies he distributed power supply,analyzes the mathematical model,working principle,equivalent circuit and related output characteristics of wind turbines,solar cells and batteries.As the key technology of microgrid,grid-connected inverters control has become a hot research topic.By introducing the types and working principles of inverters,the topology of inverters is built.This paper adopts full-bridge inverters structure,which not only improves the reliability of the system,but also improves the power quality of microgrid system.The PWM modulation strategy,voltage and current double closed-loop control strategy and PQ control method for grid-connected operation are studied.By analyzing the dq coordinate transformation,a control model based on PQ control principle is established in dq coordinates to achieve decoupling control of active power and reactive power.Through the analysis of the mathematical model and the wave diagram of the filter,the LCL filter is designed,and the characteristics of the LCL filter are analyzed.Compared with the common active damping and passive damping schemes,a passive damping scheme with series resistors on the filter capacitors is used to simplify the system.Finally,the control simulation model of MATLAB/simulink for single-phase grid-connected inverter and three-phase grid-connected inverter is built respectively.The simulation verification and analysis were carried out for the adopted scheme.