Research On Microgrid Control System Based On Multi-agent Consistency

In recent years,due to the excessive use of fossil energy in the process of economic development,resource shortage and worsening environmental problems caused by various countries have aroused more and more concerns and concerns.In order to solve these problems,distributed power generation technology with wind,water,solar and other renewable new energy as the main production capacity has attracted wide attention.Different from the centralized power generation method used in the traditional large power grid,distributed power generation has the advantages of safety,environmental protection,flexibility and convenience.As an important form of effective integration of Distributed generation(DG)and energy storage(such as fuel cells,distributed wind and solar power generation and microturbines),microgrid has two operation modes: grid-connected and isolated island.The output voltage and frequency of each distributed power supply during the operation of the microgrid are important indicators to judge the overall system performance of the microgrid.The mismatch between the generation power and load demand of each DG in the microgrid may lead to the instability of the system voltage and frequency,thus making the system voltage and frequency deviate from the predetermined value.The microgrid system can be stable only when the output frequency and voltage of each DG in the microgrid are stable near the set value of the system.Therefore,it is necessary to design an appropriate controller to compensate it.To solve the above problems,this thesis mainly carried out the following research:(1)A mathematical model is established for the micro-grid control system,and the hierarchical control structure of the micro-grid is introduced.In order to eliminate the system output voltage and frequency deviation caused by drooping control in the primary control layer of the micro-grid,this thesis studies the second-level control of the micro-grid,and designs a distributed second-level coordinated control strategy based on the multi-agent consistency theory.The proposed distributed control strategy realizes the target that the output frequency and voltage of each DG in the microgrid reach a predetermined value through information exchange and data transmission between neighboring DG in the microgrid system.In order to solve the problem of communication waste caused by data transmission based on periodic continuous time in microgrid system,this thesis adds event trigger condition to the designed distributed two-level control strategy,and proposes a distributed two-level control strategy based on event trigger communication.(2)In order to improve the dynamic performance of the microgrid system under the distributed event-triggered second-level control strategy,this thesis considers the addition of finite time and fixed time control into the distributed second-level control strategy based on event-triggered communication,and designs the distributed eventtriggered second-level control strategy under the finite/fixed time.The antiinterference performance of the system is verified by adding unknown disturbance to the control input of microgrid at a fixed time.Lyapunov method was used to prove the stability of the above methods,and Zeno behavior was excluded by calculation.Finally,the micro-grid control system is established in MATLAB/Simulink and tested experimentally.The effectiveness of the control strategy is verified by analyzing the simulation results obtained in the experiment.