May 24, 2018 - 10:40 PM
the FFT block uses a window average technique, where the window is defined by the base frequency. If you enter 50 Hz as the base frequency, the period of time is 20 ms.
The sampling frequency depends on the number of harmonics you want to be calculated. If the number of harmonics is n = 7, the input signal will be sampled with 2*(n+1) = 16 samples per base frequency (1.25 ms or 800 Hz). For more information, please refer to the PSCAD help, which tells you the number of samples for the other configurable harmonic numbers.