ABSTRACT
There have been several attempts in the 1980s to develop on-line DSA techniques to ensure that the system will survive any credible contingency involving a large disturbance. In a stressed power system when the line loading is close to the stability limits, a large disturbance such as the fault followed by clearing can lead to uncontrolled tripping of generators and cascading outages that may finally result in a blackout if proper remedial actions are not taken. Since on-line time domain simulation is not feasible, “the common practice in industry is to perform off-line studies using a manually identified set of critical operating conditions. The results of these studies are provided to the operator as an instruction and/or in a computerized form for the on-line monitoring of the power system, but will not encompass many situations which the operators may face. On-line computation of approximate limits (on power flow in critical lines) is currently limited to the use of various forms of the equal area criterion. Advanced methods should be developed to provide both accuracy and speed before on-line DSA becomes a reality” (Findlay et al. 1988, Pai 1989).
