Damping of System Oscillations with a Hydrogenerating Unit

Stabilization of the initial interconnection across Utah and Arizona between the Northwest and Southwest power systems has been aided by damping torques generated through special control of a unit in Grand Coulee powerplant in Washington. The special control is derived from local frequency, using the phase advance of the first derivative to offset the inherent lags of the hydro unit. The scheme is proving capable in augmenting the stabilizing effort from the limited amount of suitable fast response steam capacity available.