In the SimPowerSystems library there is a block for that. It is called "Discrete PLL-Driven Fundamental Value" and it is found in SPS->Extra Library->Discrete Measuremenent

you need to provide the expected frequency and a sin and a cos as reference to evaluate the angle. 

If the frequency is unknown you'll need  a second PLL which could provide this information. Just keep in mind that those block use PI controller and their dynamic might be a bit slow sometime

Luc-A

Great thanks dear Luc-Andre .. Great thanks dear sir.

I found the block and now using it. But, I didn't get the point of (sin and cos inputs). May you please shed more light .. To try it, when I put 0 and 1 as inputs for the sin and cos I get angle 90, and when I put 1 and 0 instead, I get angle 0. I realized that this is not the right way for their inputs. What to put as an input for sin and cos? On the other hand, value of the magnitude which I obtained is double the correct value ..

Thank you so much ..

The Sin cos signals serve as reference to compute the angle.

You can have a look at the example for you

Hope it helps

That has helped me a lot. Thank you for your time. Your help is highly appreciated.        I will refer to you again. Thank you.

I think that tool block is just ideal block diagram. If you want to calculate angle please derived transfer function of that circuit as a ratio of voltage in frequency domain as a numerator polynomial and denominator polynomial in closed form . For typical , you can plot graph as a magnitude response and phase response of voltage gain as a function of input frequency in frequency domain. If you want to see the waveform why does it lag or lead in angle in time domain . You just you inverse Laplace's  transform for continuous time system or Z's transform of E. I. Jury for discrete time system

Thank you Mr. Kittipong. May you please provide me a simple example.