As background, we describe frequently used feedforward wide-area discontinuous power system stability controls. Then we describe online demonstration of a new response-based (feedback) Wide-Area stability and voltage Control System (WACS). The control system uses powerful discontinuous actions for power system stabilization. The control system comprises phasor measurements at many substations, fiber-optic communications, real-time deterministic computers, and transfer trip output signals to circuit breakers at many other substations and power plants. Finally, we describe future development of WACS. WACS is developed as a flexible platform to prevent blackouts and facilitate electrical commerce.

The author discusses the need for accurate time coordination in the generation and distribution of electric power. He points out that the efficiency of present electric power systems can be increased with the addition of time and frequency technology, and that the same technology is an important ingredient in new electric power systems. Knowledge of the location of a short circuit fault can speed the automatic or manual reenergizing of a transmission line. One fault location technique requires clocks synchronized to one microsecond.>