Research On The Consensus Of Battery Energy Storage System With Droop Controller

Battery Energy Storage System(BESS)has been widely used in microgrid and the power system,so the research on the coordination and grid connection of battery energy storage system has attracted more and more attention.In many researches,the variability of communication topology,load switching and communication delay become the uncertain factors of the system.In a large-scale power grid,the physical distance results in the attenuation of communication intensity,which causes obstacles to the cooperative power supply of multiple systems.In addition,the fruit of existing research on consensus time is not satisfactory.Therefore,in order to improve the coordination and response speed of multi-agent energy storage system,this paper studies the following based on the idea of multi-agent consensus:(1)Consensus design of heterogeneous battery energy storage system based on droop controller.The coordination of frequency,active power,energy level,voltage and reactive power is realized through the information exchange of multi battery energy storage devices.In order to restore the frequency and voltage to the nominal values,an external command is introduced as the leader.Through system simulation,we can see that the two consensus algorithms can achieve the coordination of five states of multi battery energy storage system in island mode,and the voltage and frequency can be restored to the leader.Moreover,when it comes to the topology change and communication delay,the consensus input designed can ensure the convergence.(2)Consensus design of heterogeneous battery energy storage system considering geographical factors based on droop controller.The weight of the communication topology is the distance between the two battery energy storage systems,and the clustering algorithm based on the minimum spanning tree is designed.The communication topology is divided into several subgraphs,so the concept of multi-agent step-by-step consensus is proposed.It can be seen from the simulation that in the island mode,the coordination speed of battery energy storage systems can be different by the change of the position.The consensus can be reached firstly between the closest ones,and the consensus among all clusters is the slowest;the consensus can be kept well when it comes to the communication delay and load switching.(3)Finite time step-by-step consensus design of heterogeneous battery energy storage system based on droop controller.It can be seen from the formula of convergence time that the convergence time under the fixed topology is up to the initial value of the system.From the simulation results,whether island mode or grid mode,the system can converge in a short time,and can cope with the load switching and communication delay.In addition,the effect of input parameters on convergence is also studied.At the same time,it is pointed out that the faster the convergence speed,the more aggressive the system will be.(4)Fixed time step-by-step consensus design of heterogeneous battery energy storage system based on droop controller.From the calculation formula of the upper limit of convergence time,the convergence time of the system is completely determined by the parameter and communication topology.The performance of the design is verified by simulation.(5)Distributed optimal management method for Energy Internet based on battery energy storage system.Here,real-time electricity price is tracked by electricity cost increment,and global power mismatch is estimated by average consensus algorithm,and exchange power can be calculated by control strategy of energy router.The simulation results show that when the cost increment of electricity consumption converges to the electricity price,the global power mismatch converges to 0 p.u,and each generating equipment is in the optimal output state.Even if the electricity price changes and the local communication fails,the system can quickly converge to the optimal working point.