Dear Vivekanansan

it depends on the configuration your smartgrid and the configuration of your generating units but you can check the equipment typicall used on this website of Schneider

http://solar.schneider-electric.com/solution/residential-grid-tie-with-backup-power/

and on this link is a design guide for solar generating units

http://solar.schneider-electric.com/lp-solution-guide-decentralized-pv-systems-using-conext-cl-inverters/

Gerro

Dear Vivekanansan,

Pls. see the book entitled "GRID CONVERTERS FOR PHOTOVOLTAIC AND WIND POWER SYSTEMS". you can find some algorithms for grid synchronization in this book.

Saeed

Book recommend by Saeed help you.

I thank you Mr. Gerro Prinsloo, your links are very useful. 

Thanks to Saeed Peyghami  and Arpana Mishra, the book you suggest was very useful. Am expecting more practical info's for this topic, which makes easy to understand

If you are generating electricity at nominally grid frequency, are you generating it from a rotary generator of some sort or an electronic source? If the former, what sort of generator is it? And so on. There are lots of variables and reading the book Saeed recommended is a good start.

Sometimes you can connect a rotary generator directly to the mains and have it spin at synchronous frequency, with a lagging power factor (current lags voltage). Driving the rotor advances the phase of the current so it leads the voltage and delivers real power to the grid.

Electronic inverters won't do this and require algorithms as per the book. They then check how well the synchronisation has been achieved, and use that figure to determine if the external input has failed; this is called islanding protection. Islanding is where the local supply operates on its own with the grid failed or disconnected.

Please study these texts thoroughly before making any sort of connection to the grid. You can destroy your equipment (and yourself) very easily if you get it wrong.

Best wishes.

Thanks for your suggestion Mr. Tony Maine.