ig (t) = Im sinwt

Where Ig= Grid Current;

Im= Peak Current;

w- Angular frequency of grid current

you can used these equations 

ig (t) = Im sin (wt )

Where Ig= Grid Current;

Im=  Current max ;

w- Fundamental pulsation of grid 

We Thank you for your consideration of our question. just i have another question concerning the interconnection between the DC/DC converter and the DC/AC inverter. When I connect both, the laison does not work, but each one works properly. i don't know where is the problem exactly? if you have any idea share it with me. 

Dear Ilham, 

I think it does not work just because of the capacitor value of the DC-link and also the output capacitors at the end of the inverter. Try to adjust them at the lower value which system is able to work. First, design them by formulas in the references, but it is not enough to have a good response. You need to find better values for them by means of simulation and trial and error technique. Usually, these values are close to the designed values by formulas. Also, let the capacitor value at the end of the DC-DC converter attain enough energy to arrive at the reference voltage. After that let the inverter switching process start. 

First I want to clarify what do you mean by id ? is it D.C Current from solar panels  ? and what is your voltage system ?

Thank you for your time.

id is the direct current in the dq0 park transformation.

i have another question concerning the interconnection between the DC/DC converter and the DC/AC inverter. When I connect both, the laison does not work, but each one works properly. i tried to adjust the capacitors values but the problem is still existing.

the problem exist in idref value and in three-phases current waves.

The attached images show the variation of idref and ia,b,c.

i don't know where is the problem exactly? if you have any idea, file or article share with me. 

Dear Mr. Nassar-Eddine

You must first determine the maximum power point  of the PV from MPPT controller. This will give you the required reference capacitor voltage to be controlled. The capacitor voltage controller is responsible on determining the reference AC current of the inverter to extract the exact MPP from the PV. Finally The current controller controls the drawn current to preserve the capacitor voltage to work at MPP.

You can work in any reference frame, as ABC reference frame or to transform the controlled values to alpha-beta reference frame or to dq0 reference frame by the proper transformaton.

Regards

You can read our paper (Novel deadbeat power control strategy for grid connected systems) in Research gate:

https://www.researchgate.net/profile/Yousry_Atia/publications

Best Regards