Hello Janardhan,

To inject active power you just have to inject a current in phase with the grid voltage.

To inject reactive power you need to phase shift the injected current with respect to the grid voltage.

Thus, by controlling the phase and amplitude of the injected current you can control the active and reactive power injected into the grid.

Regards,

Michalis Florides.

As W=VICos phi, and VAR=VISin phi..

The answer of the colleges above is okay. You have to make the phase of the current lags behind the grid voltage by the required phase angle dictated by the reactive power required as given by Desai.

It is so that the grid connected inverter is built with controlling the output power by its controller. It is an output power controlled. Since the output voltage of the inverter is that of the grid wich is stiff, one consider it as the phase reference and adjust the phase and amplitude of the output current by setting its in phase and quadrature components.

For more details , please refer to the link:https://www.researchgate.net/publication/233902842_Simulation_and_Implementation_of_Grid-connected_Inverters

Best wishes

Article Simulation and Implementation of Grid-connected Inverters,

Please look at the synchrnous reference frame controler. You transform the ac quantities into synchronously rotaing dq frame (rotation at the grid frequency). After the transformation, the d and q components of the injected grid current cotrol the active and reactive power fed into the grid. by doing so, you not only decouple the control of active and reactive power, but also are able to use PI controllers for compensation. 

To inject reactive power you just have to inject a current in phase with the grid voltage.

To inject reactive power you need to phase shift the injected current with respect to the grid voltage.

Thus, by controlling the phase and amplitude of the injected current you can control the active and reactive power injected into the grid