Model of FFT in power systems

Anyone know how to model the FFT of the voltage singal of a power system?

The need for this model is to simulate the phasor estimation of the protective relay by using DFT model

I already have the model of the power system and took a mesurement of the voltage on a transmission line (220kV, 50Hz).

Now I want to take this voltage signal and find its frequency-domain FFT by first converting it to discrete time by a sampling time Ts of 1/600 s (sampling frequency of 600Hz) after that I used a buffer and then the FFT block like this

Paramters

Zero-Order Hold Sample time = 1/600

Output buffer size ( per channel= 600

and didn't make any change to the FFT block

but something is not going right

• it gives a magnitudes of order 10^7 while the peak amplitude of the voltage is 220kV*sqrt(2) nearly 311126 V
• Also the frequency axis is not right, I don't see the fundamental frequency of 50 Hz of the original wave

Is there any changes I could make to make this go right?