Coordinated defense plan protects against transient instabilities

The electricity generation, transmission and distribution systems in major countries are planned, operated and protected so as to withstand any hazards that are likely to most affect them (short circuits, tripping of a line or generating set), without damage to customers. However, compliance with normal dependability and security practices does not result in a fully safe system protected against major collapses. These may result from the accidental coincidence of more fragile operating conditions and serious damage or from many successive adverse hazards far beyond those against which precautions are generally taken. This paper describes a coordinated power system defense plan, the goal of which is to prevent large regions of France or the entire power network from suffering blackouts and to accelerate restoration.