A. new horizon for system protection schemes

Interconnected grid operation, control, and security will be revolutionized by a system protection scheme that safeguards the grid's integrity by adapting its responses to the most severe, unforeseen disturbances. The new approach takes advantage of power system resilience to the initial impact of even the most severe disturbances. The disturbance causes changes of system vulnerability parameters that are used by the protection to direct pre-selected measures to affected locations. A system protection that sustains system voltage stability and incorporates a simple emergency strategy is outlined. The approach allows practical and reliable, modest cost schemes that can gain considerable financial benefits in the operation and control of the grid.