Governing Characteristics for 820,000 Horsepower Units for Grand Coulee Third Powerplant

In selecting parameters for large hydropower generating units such as those for the Grand Coulee Third Powerplant, control characteristics to satisfy power system needs can strongly influence economics of the design. The needs for abnormal mechanical inertia and expensive reduction of the penstock water starting time are shown to be mitigated by refinement of governor characteristics. This paper describes selection of controllability to meet power system needs, relation of controllability to mechanical inertia and the penstock time constant to facilitate economic proportioning, influence of the governing system and its refinement with several new features for improved performance.