Analysis On Power Coordinated Coritrol Strategy Of DC/AC Micro-Grid With Hybrid Storage System

Photovoltaic generation has been widely used with the advantages of clean,renewable and continuous.However,photovoltaic generation which is intermittent and unpredictable will affect the stable operation and quality control of the utility grid if it is connected to the grid directly.Therefore,it needs to be connected to the utility grid through Micro-Grid.DC Micro-Grid has developed rapidly with the increasing DC load,while the AC Micro-Grid is still huge.Therefore,the DC/AC Micro-Grid contains DC and AC bus has been the primary trend of Micro-Grid research.How to control the power of the Micro-Grid is the crux to the normal and steady running condition of the DC/AC Micro-Grid effectively.The point of the power control is to control the power flow between the converters to realize the power balance of the Micro-Grid system.Aiming at power control,a lot of research has been done while lacking the crux conclusion.For this issue,this paper studies the DC/AC Micro-Grid applied to buildings set hybrid storage module combined power and energy characters.A coordinated power control strategy for DC/AC Micro-Grid under various variables is proposed,the main research contents are as follows:Firstly,the photovoltaic generations storage DC/AC Micro-Grid topology for buildings is built based on the study of DC/AC Micro-Grid structure,which mainly consists of photovoltaic power generation module,hybrid energy storage module,load module and public power grid module.The modeling and simulation analysis of the photovoltaic power source is carried out,and the maximum power point tracking method based on variable step size disturbance are discussed.The accuracy and response speed of maximum power point tracking are discussed through simulation.Secondly,comparing the main performances of various energy storage media with the various factors such as service life,power density,energy density and environmental protection,a lead-lithium battery and a super capacitor are combined to the hybrid energy storage system.The connection mode and system architecture of the hybrid energy storage unit are determined after the simulation modeling and charging and discharging characteristics are analyzed.The active architecture mode paralleled with the DC bus through DC/DC converter,which can fully optimize the charge and discharge characteristics of the energy storage medium and prolong the service life of the hybrid energy storage system.Finally,a power control strategy for DC/AC Micro-Grid is proposed.The operation mode of each unit is determined according to different operation state of the Micro-Grid to ensure the power balance.When the operation mode of the Micro-Grid changes,the converters of each unit adjust their operation modes according to the threshold,and the power exchange of other units is supplemented.The total power reaches a dynamic balance,thereby achieving a reasonable distribution of power among the units.The validity of the control strategy is testified by Simulink simulation eventually.