Un-Identical Units for One Power Plant Possible?

For matching generating capacity to varying loads, it may be useful to have one or two units sized at about half the capacity of the others. That way, if the load increases a little, you can bring on a smaller unit rather than a larger one.

Every case is different. If there are, say, a dozen turbines, they might well all be the same size. (Each additional unit = 8.33% of total capacity). But if there were only four turbines, each additional unit would be 25% of total capacity, which might be more than you need to add at any one time.

Hi Tornado, thank you so much.

What if we don't have variation in load? And our main aim is to make optimum use of discharge in the river? I mean try to generate to maximum and 10% additional capacity in summer when we have more water in the river and vice versa in winter. How will that effect having un-identical unit?

I think this situation would be analogous to the previous one. Instead of matching your output to load demands, you would be matching to the "run of the river." If this match needs to be within say 10%, then one or two units should be not more than 10% of the total capacity of the entire set.

And then I am curious: how do the loads (consumers) collectively match themselves to the total hydro station output?

(I am not a hydro plant designer; just asking some common-sense systems-type questions. There are some CR4 threads on hydro plants, and maybe there will be some input from those guys....)