Matlab Simulink - Load disturbance

Hi! I would like to simulate in Simulink "Load disturbance" or Load changes. Currently I use output signal from Step as a Load, but I need Load disturbance. I want that my step signal(which represents Load) vary inside some borders(lets say +/- 10% of some nominal value).

I'm trying to simulate off-grid(or islanded) hydropower plant, and this part is making me problem. So any help here? What blocks I should add after my "step response".

Answer 1

[Azzi Abdelmalek]

You can use a Band-Limited White Noise block

[Robin Beene]

I think that's what I am looking for. Thank you