Simulation Study On Operation Control Of Hybrid AC/DC Microgrid

Hybrid AC/DC microgrid technology with important engineering value and broad application prospects can improve the flexibility ? power supply efficiency and economical efficiency of distributed generators connecting grid.The operation control mode is the basis of stable and economical operation of hybrid AC/DC microgrid and considerable great practical application value.The operation control issue of hybrid AC/DC microgrid is divided into four sub subjects: the operation control in grid-connected mode and island mode,the switch between grid-connected mode and island mode,the coordinated control of the micro turbine and battery energy storage in island mode.Aiming at the operation control in grid-connected mode and island mode,based on the voltage-power droop control of bidirectional AC/DC power converter and the power-voltage droop control of battery energy storage in DC microgrid,the operation control strategy of DC microgrid is designed firstly.Secondly,based on the virtual synchronous generator control of the micro turbine,the frequency division control of AC microgrid is designed to ensure the normal operation of the system.At the same time,the limited power control of photovoltaic and wind power generator is designed to limit the surplus of renewable energy,the normal power consumption of microgrid is ensured.Aiming at the problem of switch between grid-connected mode and island mode,Firstly,the voltage source characteristics of micro turbine based on virtual synchronous generator and conditions of seamless switching from grid-connected mode to isoland mode are analyzed.Secondly,conditions of seamless switching from isoland mode to grid-connected mode are analyzed,and the pre-synchronization control unit is designed to ensure the smoothness of this switch.Aiming at the problem of coordinated switching between micro turbine and battery energy storage in island mode,the control that ensure smooth switching between the voltage outer loop and the power outer loop is designed based on the same current inner loop,the smooth switching between constant power control and virtual synchronous generator control is realized.And the coordinated switching logic of the micro turbine and the storage battery is designed to guarantee the stable operation of microgrid in the process of micro gas turbine input and exit operation.