| In recent years,distributed generation with renewable and non-polluting properties have received widespread attention and development,however,due to the intermittence and volatility of the distributed generation,the problem of unstable operation and complex energy management will be caused when the distributed power supply is connected to the network.In order to give full play to the advantages of the distributed power supply,the concept of microgrid is proposed.As an independently controllable system,the microgrid can not only be connected to the grid,but also can independently supply the local load from the main grid.Under the mode of island operation without large grid support,how to achieve coordinated control of distributed power sources is an important basis for ensuring the stable operation of island microgrid systems and improving clean energy utilization.At present,most of the research on distributed coordination control of microgrid is focused on economic optimization and electricity market transaction,and it also involves the energy management and power quality of microgrid,but there are few specific microgrid models to be analyzed,and the load classification management in the system has not been considered.In addition,the research of distributed coordination control strategy for microgrid is mainly focused on the balance of supply and demand of the power system,but the requirements of the power quality index are not considered.Therefore,based on the application of multi-agent technology,combined with the concepts of energy management and hierarchical control,a hierarchical control strategy is proposed in this thesis based on MAS for islanding microgrid.Through the coordinated control and optimized scheduling of distributed generations and loads in the island microgrid system,the power supply and demand balance in the system can be achieved while meeting the power quality indices requirements.The main contents of this thesis are as follows:(1)The background and significance of the selected topic and the concept and research status of the microgrid,multi-agent technology and hierarchical control are introduced.Then,the mathematical models of the three kinds of distributed power supply for wind/pv/battery are given,and use Matlab/Simulink to build a simulation model to perform simulation analysis on its operation characteristics.Then the principle of the three control methods of the existing micro-power supply is analyzed,and a simulation model is established on the simulation software.The results of simulation examples show the correctness of the three control methods.(2)A hierarchical control strategy based on multi-agent technology is proposed.For the energy scheduling problem of island microgrids,the coordinated control strategy of MGCC Agent in the central control layer is designed.In order to ensure the power supply of the important load in the system,this thesis divides the load according to the priority,realizes the hierarchical management of the load,and solves the problem of insufficient output power of the islanded microgrid.When the load and micro-power supply of the system are switched,the main control micro power using the traditional droop control in the bottom control is easy to cause the bias of the bus voltage and frequency.An improved droop control method is proposed for the problem,and the simulation verification is carried out,the results prove the effectiveness of the control strategy.(3)The coordination control and the implement method of the islanded microgrid are formulated by combining the thought of the hierarchical control and the energy management with the multi agent technology,and the control strategies of load agent and MGCC agent in islanded microgrid were designed.Finally,by combining the microgrid model built with Matlab/Simulink and the multi-agent system,the effectiveness of the hierarchical coordinated control strategy under distributed power output and load fluctuation is verified. |
PDF Full Text Request