Phasor measurment unit

I am trying to measure the phase magnitude voltage and its phase angle of the three phase AC system using arduino due and gps module with data logging to display to lcd module through wirelss medium.Is there any way to take the ac signal from source as a input and compute it to calculate phase angle and volatge magnitude?

How do you plan to sample the AC signal? What voltage does it have? That's the hardest part. Everything else follows.

Phase difference: you could use peak or zero crossing detection. In case of peak detection you can distinguish between the positive and negative half of the cycle but the timing may be less precise than with zero crossing detection. You could consider a combination of course.

Voltage: safest is to use a dedicated AC voltage sensor, which typically provides RMS voltage, but assuming clean sine waves that's all you need to calculate peak.