I’ve done level control for about 30 hydro electric power plants but with relatively small headponds or reservoirs, between 20m^6 to 50,000 m^2. You can calculate the gains to achieve critical damping, it was one of the first examples in my university controls textbook.

Getting filtering and update rate right is also important.

For me the most complicated part when doing manually was the delay, because the water from the intake gates do not reach the headponds inmediatly. What I like is that the tool considers the delay in the tuning.

Sounds like a different civil arrangement than I am used to. Is there a link to one of the plants you can send me so I can see the layout? I mostly work on high head run of river plants, but some are an upper and lower arrangement where the trail race of one plant is the head pond of the next

Not sure I can (legal reasons?), but suffice to say thay feed multiple stations with multiple relatively large machines (+10MW). In some cases they have daisy-chained basins, so there are also level inner-loops to be tuned. So the approach has been using the pidtuner for tuning the inner loops first by keeping the outloops in manual. Then tune the loops outwards using the same approach. This has been the winning combination.

Thanks for the details. I have not worked on a plant that had intake gates upstream of a headpond so was curious as to what the layout was. The nice thing about hydro is that just about every plant is unique!