Hi,
what's your DC source voltage? You must have (Vdc/2)>V_grid_peak if you are using IGBTs with diodes. Is your DC source symetric with a neutral point? Have you chosen you LC filter value? You will need a PLL to lock your inverter's output voltage frequency reference to the Grid's voltage, and also an RMS controller to control your output voltage amplitude. Finally, to be able to inject or consume Active & Reactive Power, you will need a droop controller to control your output voltage amplitude & phase references regarding your power references.
If you do not want to use a droop controller, you can set your inverter to work as a current source by only controlling your output current reference. You still need to fulfill the Vdc requirements though.
Greg
