Research On The Coordinate Operation Of Multiple Micro-source And Energy Management Strategy In Dc Micro-grid

With the development of national economy,on the one hand,the traditional fossil energy cannot satisfy the demand for energy,on the other hand,the environmental pollution caused by the excessive use of energy is a serious threat to human survival and development.Distributed energy which is connected to the power grid in the form of micro-grid,reduces the negative influence of intermittent distributed power on power grid,improves power supply reliability and power quality,becomes an important technical path to solve the energy problem.Dc micro-grid does not involve in frequency,phase and reactive power problem of the power grid,which greatly improved the controllability and reliability,is more suitable for the access of distributed power supply and load.In this paper,the related research on DC micro-grid is carried out.First of all,this paper introduces the working characteristics of micro-sources,energy storage devices and converters in DC micro-grid and so on,establishes their mathematical model respectively.Then the relevant control strategy of various units are introduced.The simulation has been carried out to verify the proposed model and control strategy.These jobs lay the foundation for the study of micro-source coordinated operation and system energy management technology in the following chapters.On the basis of understanding the characteristics and control strategies of micro-sources,this paper then summarizes control method of parallel operation of micro-source,and analyzes the basic principle and shortcomings of dc droop control strategy which is widely used.Aiming at the shortcomings of the droop control,master-slave control strategy based on the current tracking is proposed.These two control strategies are compared respectively in three aspects:current(power)distribution accuracy,voltage quality and impedance adaptability.The advantages of master-slave control in these three aspects and its stability are also demonstrated.Then the detailed simulations and experiments for the proposed control strategy are carried on.simulation and experimental results prove the correctness and the effectiveness of the proposed control strategy.After solving the problem of parallel operation of micro-source,this paper regards a typical dc micro-grid structure as the research object,proposes a energy management strategy which can improve the running performance of dc micro-grid.It could be divided into three big running mode and 11 specific working modes.The power definition standard of each working mode is put forward and the simulation of several typical mode switching is carried out.The simulation results show the correctness and validity of the proposed energy management strategy.