First of all sources need to connect with PMSG (permanent magnet synchronous generator).  Thereto the output of PMSG will be fix with respect to time. After that the output of PMSG have to connect with three phase rectifier. This rectifier circuit output should be connect with a GTI ( grid tie inverter). 

Go for the following  steps.

1. Convert AC to DC. It does not  matter that the AC from the source is pure sinusoidal or not. Most of the sources do not produce pure sinusoidal.

2. Use a three phase inverter .

3. Ensure the amplitude, frequency and phase matching using feedback from the grid.

4. You may use the modules available in the market.

Once the signal is fed to the rectifier irrespective of frequency variations it get converted to DC with ripples .Connect a higher value capacitor to reduce ripples. As Muhammad Shafiq mentioned Inverter need to be taken care while synchronizing with the grid.

Thanks a lot. But, what is the suitable technique  for the AC-DC converter control?, particularly how to choose the Modulation technique for PWM, some available techniques like the SPWM(Sinsoidal Pulse Wids Modulation) and SVC(Space Vector Control)-PWM  depends on the source frequency.

1. First convert AC to DC using diode bridge.

2. Then use proper filtering capacitor.

3. Convert this signal to AC using PWM. You may use SPWM. 

4. Ensure the amplitude, frequency and phase matching using feedback from the grid.

of Technology

Once the signal is fed to the rectifier irrespective of frequency variations it get converted to DC with ripples .Connect a higher value capacitor to reduce ripples. As Muhammad Shafiq mentioned Inverter need to be taken care while synchronizing with the grid.

Thanks a lot. For the AC-DC stage I am required to use a VSC (VOLTAGE SOURCE CONVERTER) not any other rectification technology. So, I need a suitable way to design this VSC AND ITS CONTROLLER.

Some electric circuits has batteries as a DC source and also has a AC Bus. When you need to integrate the backup source from the batteries, then you used AC to DC converter and then include the DC batteries followed by converting the combined DC back to AC. Hence, you have back-to-back AC-DC-AC arrangement.

Hope this helps answer your question.

Professor Yehia Khalil

Yale University

USA