A New Transient Stabilty Control

Disturbances threatening transient stability commence by accelerating generators in a limited area of the total transmission grid. Usually, only after one second, when this accelerating energy has been spread to other units, would stability be lost. Capitalising on this fact leads to a new approach to the control of transient stability. It would utilise simple, fast-acting measures capable of local control at major substations for meeting the initial impact of the disturbance. These measures involve the selective switching of shunt capacitors and reactors, only at substations surrounding the initially accelerating generators. This quarantines, and so diminishes the initial accelerating energy as it flows past these substations. A later switching on the backswing would further reduce the energy transfer between the system's generators, so damping inter-unit oscillations. The new control procedure is capable of extending existing transient stability limits.