Computation of simultaneous available transfer capability under thermal and voltage security constraints

This paper proposes a method to compute
the Available Transfer Capability (ATC) of a power
system under both thermal and voltage security constraints.
The objective is to determine, in some optimal
manner, the ATC of several simultaneous transactions,
such that any postulated contingency does not
cause voltage instability nor thermal overloads. Thermal
constraints are derived for every branch likely to
be overloaded in post-contingency states. Voltage security
constraints are derived from voltage unstable
post-contingency scenario, obtained by Quasi Steady-
State simulation, a fast time-domain method. The paper
also addresses the discrimination problem, i.e. the
fact that the computed ATC might favor some trades
to the detriment of others. Variants will be discussed
to deal with such situations. The method is illustrated
on an 80-bus test system.