Research On Microgrid Frequency Control Based On Multi-agent System

Vigorously developing and utilizing renewable energy is a national energy strategy that promotes the transition of low-carbon energy and the upgrading of the energy system.As distributed power sources such as photovoltaics and wind power have randomness,fluctuations,low energy density,and large number,they have a large dispersion in space and geography,which has a great impact on the operation safety of traditional power grids.The microgrid can effectively accommodate various distributed power sources and adopt effective control strategies to achieve internal supply and demand balance.It is an effective grid form for organizing and utilizing distributed energy generation.When the output or load power of distributed generation in microgrid fluctuates greatly,the active power of microgrid will be unbalanced,which will affect the frequency of the whole microgrid system.Therefore,it is necessary to take measures to control the frequency of microgrid in time.This paper first introduces the main structure and overall operating characteristics of microgrids,analyzes and studies the concepts,characteristics,advantages and disadvantages of various distributed units such as photovoltaics,wind turbines,combined heat and power,and energy storage batteries in microgrid systems,and establishes the output models of different distributed power sources.The mathematical model of the three-phase inverter is established in different coordinate systems.It lays a theoretical foundation for the research of frequency control strategy in chapter three.Then the basic principle and characteristics of droop control are introduced,the basic principles of each part of the controller and the specific principles of parameter setting are analyzed in detail,and the overall design and research of the microgrid control strategy based on droop control are analyzed,and the power distribution mode between distributed power sources is analyzed.Aiming at the inherent defect of traditional droop control,in order to eliminate the frequency difference,an optimized multi input single output fuzzy controller based on multi-agent system is proposed as the secondary frequency control strategy of distributed power supply.In addition,several control modules of this strategy are designed and studied.Finally,in order to verify and evaluate the superiority of the control strategy based on the multi-agent system,the MATLAB/Simulink micro network simulation platform is built,and the dual computer parallel simulation model of the droop control scheme and the micro network secondary frequency control scheme based on the multi-agent system is established.The simulation,analysis and comparison of the two control strategies are carried out under the conditions of islanding load switching operation,islanding/grid connection switching and grid connection load switching operation,respectively,which verify the correctness of the analysis results,the correctness and effectiveness of the control strategy,and the advantages and economic benefits of the micro grid secondary frequency control scheme based on multi-agent system.