Hey!
It’s about control systems for hydro power plants, where one of the main role has turbine-governor which should be able to control speed(frequency) of the generator.
But can someone explain me why on the some block diagrams there are speed and power feedback while some block diagrams use only speed as feedback to control frequency constant. What’s deal if we have power too as feedback?
Look the following picture and you will know what I am talking about.
http://oi48.tinypic.com/iqdc08.jpg