Dynamic performance and security of interconnected systems

The characteristics of a power system that have become of increased importance because of interconnection are discussed. They are: very small damping of disturbances; the need for more voltage support; much more complexity in design, operation, control, protection, and analysis; and much more pervasive and numerous controls. Some new problems introduced by interconnection are examined. They are: the appearance of spontaneous tie-line power oscillations under certain line loading conditions; the appearance of voltage instability with resulting voltage collapse; and widespread blackouts.<>