Research On Coordinated Control Of Island Ac Microgrid Based On Photovoltaic-Energy Storage-Diesel Generator

The microgrid contains a large amount of renewable energy,and the output power of renewable energy is easily affected by external factors,with uncertainty and intermittency,which can affect the stable operation of the microgrid system.Therefore,it is necessary to coordinate and control the various micro power sources containing renewable energy in the microgrid system to ensure stable operation of the system.This thesis will study the coordinated control of isolated AC microgrid composed of photovoltaic,energy storage and diesel generator.Firstly,the development status of microgrids at home and abroad was introduced,and the control strategies of distributed power inverters and microgrid coordination control strategies were introduced and compared.Photovoltaic power generation system,energy storage system and diesel generator are selected as the components of the island AC micro grid system.The principle analysis and modeling of these three micro power sources are carried out,and the simulation verification is carried out,which lays the foundation for the following research.Secondly,the control strategy for the inverter side of the island AC microgrid proposed in this article was introduced.The output of the energy storage system and the photovoltaic power generation system are both direct flow.In order to integrate them into the AC bus,appropriate control strategies need to be adopted on the inverter side.To maximize the utilization of photovoltaic energy,the inverter side of the photovoltaic power generation system adopts PQ control as the secondary power source;The energy storage system,as the voltage and frequency supporter of the island system,needs to absorb or release energy.The inverter side adopts VSG control to increase inertia and damping for the system,and its advantages are compared with those of droop control through simulation.A theoretical analysis was also conducted on the voltage imbalance phenomenon caused by the frequent connection of single-phase loads in the isolated AC microgrid system,and the voltage imbalance compensation control strategy was studied and verified through simulation.Then,a coordinated control strategy was proposed for the AC microgrid of the photovoltaic fuel storage island,and tasks were assigned to each of the three micropower sources in the coordinated control layer based on their respective characteristics.Secondary compensation control is also adopted for voltage and frequency to further improve system stability.Based on the principle of maximizing the utilization of photovoltaic power,photovoltaic power generation systems must always be connected to the microgrid;The energy storage system coordinates the energy flow within the system based on the sag curve set by VSG control,and provides voltage and frequency support;The diesel generator is used as the standby power supply to supplement the power shortage.The coordinated control strategy proposed in this article was validated and analyzed by building a simulation model.Finally,build a seven port coordination controller experimental platform.Introduced the software and hardware design and conducted software debugging.The reliability and stability of data communication were verified through simulation experiments;The human-computer interaction interface enables real-time observation of the operating status of the equipment and the effectiveness of parameter settings.