Research On Distributed Optimal Control Of Multi-agent Finite-time Islanded Microgrids

In order to solve the problems of frequency and voltage deviation,rational power distribution and long system response time caused by traditional sagging control of Microgrid(MG),and overcome the defects of high communication burden and low reliability of the system under centralized control mode.In this paper,the distributed control concept and principle of Multi-agent system(MAS)is applied to microgrid control,and each distributed generator(DG)is regarded as an agent,which can conduct information interaction with its neighboring DG through itself.The disadvantages of microgrid central controller(MGCC)in the traditional centralized control mode are overcome.The coordination among various DG saves the construction cost of communication facilities and network,and improves the flexibility and reliability of DG.At the same time,it can meet the "plug and play" needs of DG.The control strategy designed in this paper can adjust the frequency voltage to the rated value and allocate power on demand.On this basis,the economic optimal operation of microgrid is realized.The main research contents of this paper are as follows:(1)The mathematical model of economic dispatch of microgrid is established,and the characteristics of incremental cost of constant consumption are analyzed,and the solution methods of centralized and distributed economic dispatch are studied.Considering the multi-objective optimization control problem involved in the operation of microgrid,the economic operation of microgrid should be considered while solving the problem of frequency and voltage stability,which provides ideas for the subsequent application of MAS distributed control in microgrid control.The cost increment of each DG unit converges to the same rate,and obtains the optimal output power,realizing the non-differential regulation of frequency and voltage recovery.(2)Aiming at the economic optimal operation of microgrid and subsequent system voltage frequency regulation,a layered and distributed real-time optimization strategy is proposed based on hierarchical control of microgrid and MAS consistency theory.The microgrid is divided into different layers,and the MAS algorithm is used to realize the distributed control of each layer.In the first layer,frequency and voltage deviation caused by droop control is adopted.In the second layer,MAS consistency algorithm is used to introduce frequency and voltage compensation for compensation,so as to ensure that the output frequency voltage of DG is always stable at the rated value.The third layer uses the local communication of DG to exchange the incremental cost information to achieve the same incremental cost of each DG,thus effectively reducing the system operation cost.(3)With the control goal of DG meeting the optimal incremental cost operation and minimizing the total operation cost of microgrid system,a distributed MAS finite-time frequency and voltage errorless correction regulation strategy is proposed.Considering the generation constraints of DG,the first-order MAS consistency protocol is adopted,and the incremental cost of each DG converges to the average consistent value by using the information exchange of each DG,so as to achieve the economic optimal operation.For the optimal control of frequency and voltage,the information interaction among various DG is utilized to generate new frequency and voltage reference values.DG tracks the leader and tends to be consistent with them,thus completing the non-differential control of system frequency and voltage.