| In recent years, in order to alleviate the pressure of the traditional non-renewableenergy generation, to meet human demand for electricity, many countries in the world areactively utilizing the renewable energy generation, developing the distributed generationtechnology. As the power grid accesses a large number of distributed generations, thisbrings huge challenge to the power grid’s security and stability. Microgrid technology caneffectively play the advantages of distributed generation, solve the problems thatdistributed generation brings. In the system of microgrid, the inverter is one of the vitalconnection interfaces of system and power grid, the control of it can realize the system ofmicrogrid being connected to the grid or not at any time, realize the function of plug andplay.For the purpose of studying the control strategy of two modes inverter, this paperestablishes mathematical model of three-phase inverter, designs the control strategy andcontrol parameter of the inverter when stand-alone mode and grid-connected mode,. Wheninverter connected to the grid, it is controlled by the synchronizatio controller and the twokinds of operation modes are validated through the simulation.This paper detailed studies mode switching control strategy, and analyzes the effecton the output of inverter of different parameters and different switching modes during theprocess of switching, also points out that the change of load will impact on the systemwhen switching. This paper determines control strategy of the inverter when switching,verifies the switching process through simulation, and achieves smooth transition.Finally, this paper sets up the three-phase inverter experimental platform withTMS320LF2407as controller chip, writes the control program. The program of open loop,single current closed loop and the PI adjust, SPLL algorithm are given in detail. In thisexperiment, the inverter can run successfully on open loop and grid-connect, whichverifies the rationality of the experiment platform, and this makes preparations for thefurther experiment. |
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