This paper presents a security assessment approach for operational pla
nning studies that provides the operator with accurate boundary visual
ization in terms of easily monitored precontingency information. The a
pproach is modeled after traditional security assessment procedures wh
ich result in use of a nomogram for characterizing the security bounda
ries; these procedures are common among many North American utilities
today. Therefore, the approach builds on what is already familiar in t
he industry, but it lakes advantage of computer automation and neural
networks for generating and understanding large data bases. The appeal
of the approach is threefold: it provides increased accuracy in bound
ary representation, it reduces the labor traditionally required in gen
erating security boundaries, and the resulting boundaries, encoded in
fast, flexible C subroutines, can be integrated into energy management
system software to provide the operator with compact, understandable
boundary illustration in real time. These improvements are of particul
ar interest in securely operating transmission systems close to their
limits so as to fully utilize existing facilities.