On-line transient stability assessment in operation-DEEAC in Northeast China Power System

Achievements in on-line transient stability assessment of the Northeast China Power System are reported in this paper. The improved dynamic extended equal area criterion (DEEAC) is interfaced to a state estimator with DBMS in an advanced EMS environment. Thousands of DEEAC results, recorded from snapshots of on-line estimations have been thoroughly checked with an off-line numerical integration method. For first swing stability assessment of both symmetrical and asymmetrical faults, there are only less than 1% of cases whose errors exceed 10%. Moreover, all large errors occur with mild contingencies only. Each critical clearing time (CCT) calculation takes about 10 s CPU time of a VAX-11/785 computer. In an HABITAT environment (developed by ESCA Corp.), the on-line EEAC package is very user-friendly.<>