Problem in FFT Analysis

I have built a model of inverter connected Grid.

. In Powergui block I have put discrete and one microsecond.

. In setting I have put Time: Tout

signal logging

Data stores

Answer 1

[Sayan]

Hi NIBEDITA,

It seems your steps are correct to generate the FFT of the signal. It would be better if you could share the Simulink model. However, you can try the following possible changes in the FFT analyzer window to fix the issue:.

• Ensure the fundamental frequency is correct for the signal. You have selected 50 Hz as your fundamental frequency, which is different from the signal frequency as the period of the signal is nearly 0.92 sec, i.e., nearly 1 Hz.
• If you need to set a different fundamental frequency than the signal frequency, please ensure the frequency is available in the signal. The display style is selected as "Bar (relative to fundamental)". So, the FFT bar graph will show the harmonics relative to the fundamental frequency amplitude.

If the issue still persists, you can use the Fourier block (available at Simscape / Electrical / Specialized Power Systems / Sensors and Measurements). You can use this block to get the amplitude and phase angle of the harmonics in the signal.

You can find more information on the block and its parameters in the following documentation.

https://www.mathworks.com/help/sps/powersys/ref/fourier.html

You can type "power_Fourier" in the command window to open an example model using the block to know its use case.

Hope this helps in resolving your issue.