Research On Control Strategy For Photovolaic Ac Microgrids During Island Operation

With the rapid development of the economy and the life quality continuous improvement,the demand of electricity gradually increased,the power quality and power supply reliability requirements are getting higher.Use the traditional non-renewable energy to supply power,not only facing the crisis of energy depletion,but also caused serious environmental pollution.It is an effective method to resolve the contradiction between economic development and environmental by adjusting the energy structure and using clean energy.So a variety of new energy distributed power generation has been rapid development,through integrated control these distributed power,making it as a whole,provide a manageable unit for the grid or users,it can maximize use the advantages of distributed power,based on this concept,scholar put forward the microgrid.When the microgrid operation in the island mode,due to wind speed,light,temperature and other natural conditions,it will lead to the output of the distributed power unstable,and then it affect the normal operation of microgrid.In this paper,the photovoltaic AC microgrid is the object of study,The main contents are described as follows:Firstly,it discusses the significance of the research,summarizes the current research situation at home and abroad.The main control methods of the existing AC microgrid are analyzed.Secondly,the structure of PV microgrid is analyzed,and the performance of PV cell and battery in AC microgrid is studied.The mathematical model of control circuit is established.Thirdly,the parallel operating characteristics of the inverter in the microgrid is analyzed,and the parallel control method of the photovoltaic AC microgrid inverter is introduced.In view of the shortcomings of the fixed coefficient droop control,the integral adjustable coefficient droop control method is proposed.The energy flow relation of photovoltaic AC microgrid and the working mode of each micro power are analyzed.Then,the control method of distributed power is designed.Coordinate control of batteries and photovoltaic cells to ensure the entire AC microgrid system energy balance.Finally,the simulation model of photovoltaic AC microgrid is set up in MATLAB/Simulink environment.The simulation results are carried out under different conditions.The simulation results show that adjustable coefficient droop control can achieve accurate power share,and in the case of load change,it can improve the control accuracy of the system.At the same time under different conditions,the photovoltaic microgrid can be stable and reliable operation.