sorry for my poor english, i'm using google translate to explain and also don't understand the code well

in this line you are using the calculation for seconds to calculate the result of tic. As a result, the use of more than 600 steam per second

local vanilla_turbine_fluid_usage = 60 / 6 -- Default Factorio fluid usage per MW, rounded up
turbine.fluid_usage_per_tick = vanilla_turbine_fluid_usage

I modified it to this to give the results I believe are correct according to my testing.

local vanilla_turbine_fluid_usage = (60 / 6 * custom_turbine_power) / 60 -- Default Factorio fluid usage per MW, rounded up
turbine.fluid_usage_per_tick = vanilla_turbine_fluid_usage

There may be errors in steam-engine but I don't know how to fix it because it only uses 2 steams per second

I pressed the wrong button but don't know how to delete it. So becoming 2 replies

No worries.
I did catch this error in my gameplay... I ended up consuming way more steam than needed.
But, a new version was made by DanuaDangoo which already correct this, and also adds other features. Check it out. I left the link on this mods's description.