Research On Multi-Agent Coordination Control Strategy For Microgrid Energy Storage System

In order to reduce the use of fossil energy and promote the use of renewable energy,energy storage microgrids are gradually being widely used,energy storage microgrid has gradually been used widely.Since renewable energy is intermittent and volatile,the introduction of energy storage devices in microgrid can effectively regulate the system fluctuation and ensure the safe and stable operation of microgrid.In practice,multiple energy storage units are required to meet the power demand of the microgrid.When multiple energy storage units work continuously in inconsistent State of Charge(SoC),it will lead to over-discharge or over-charge of some energy storage units,which will affect the life of energy storage units and the stability of microgrid.Based on this,in order to realize the multi-storage SoC equalization,this thesis proposes a multi-storage coordination control strategy based on the multi-agent consensus algorithm to realize the equalization of multiple storage unit’s SoC and based on this,proposes a variable regulation factor SoC equalization strategy to effectively improve the SoC equalization speed,and the main work of the thesis contains the following four aspects.Ⅰ.Modeling of optical storage DC microgrid systemDesign the overall structure of the optical storage DC microgrid system,establish the mathematical models of PV cells and energy storage batteries,and on this basis analyze the operating characteristics of PV cells,energy storage batteries and the SoC characteristics of energy storage batteries.Ⅱ.Research on multi-intelligent based multi-storage coordination control strategyTo address the problem that the sag control current distribution accuracy,line impedance,battery capacity and other factors affect the SoC equalization degree and speed of energy storage units,a multi-agent consensus algorithm based multistorage coordination control strategy is proposed,which correlates the sag coefficient and SoC through the inverse cotangent function,so that the sag coefficient can be varied within a certain range to control the charging and discharging process of energy storage units,reduce the voltage deviation,improve the current distribution accuracy,and better realize the SoC equalization of energy storage units.SoC equalization of energy storage unit and improve the equalization speed.Ⅲ.Research on the communication strategy of multi-intelligent body energy storage system based on event-triggeredFor the above equalization strategy in the energy storage unit using the traditional periodic communication method will cause unnecessary communication resources waste,high frequency of controller update,a kind of adaptive event-triggered communication method is proposed,which can effectively reduce the communication frequency of energy storage unit by comparing the size of the state variable error and threshold value in the energy storage system and dynamically adjusting the event-triggered parameters.Simulation results show that the number of event-triggered communications is reduced from 103 for periodic sampling to 102 and 101 orders of magnitude,and compared with centralized and distributed event-triggered,adaptive eventtriggered has the least number of communications,which saves communication resources and reduces the communication burden of the system,and has a better control effect.Ⅳ.Case validation and analysisTo verify the effect of the proposed control strategy,a model is built in MATLAB/Simulink platform and six different operating conditions such as load disturbance,energy storage unit failure and line impedance change are simulated and analyzed,and the results show that the proposed strategy can achieve SoC equalization of the energy storage unit under different scenarios,improve the SoC equalization speed,increase the speed by 7.5%-26%under different working conditions,and improve 14.325%on average,and the line impedance changes The current distribution accuracy can still be improved in the case of line impedance change,in order to improve SoC equalization accuracy and reduce bus voltage fluctuation.Compared with periodic communication,the communication strategy of adaptive event-triggered can effectively adjust the event triggering frequency when the system operation state changes,significantly reduce the number of communications between energy storage units,save communication resources.In summary,this paper proposes a coordinated control strategy based on the multi-agent consensus algorithm and an adaptive event-triggered multi-storage communication strategy to address the problems of current distribution accuracy and line impedance that affect the SoC equalization degree and speed,as well as the problems of high communication frequency and unnecessary communication resource waste caused by the traditional fixed-cycle communication method for multiple energy storage units.The simulation and experimental verification results show that the proposed strategy can achieve SoC equalization,improve SoC equalization speed,and reduce the communication frequency between energy storage units to save communication resources.