Abstract—Security-constrained generation scheduling (SCGS)
is an indispensable tool for independent system operators (ISOs)
to plan a secure and economical hourly generation schedule in the
daily/weekly ahead markets. Power outputs of thermal units are
usually formulated as step functions in almost all literature on
SCGS, i.e., the generation level schedule is taken as an energy
delivery schedule. The ramp-rate constraints are also simplified
as limits on the differences of generation levels in consecutive time
periods. However, it has been found in our previous work that the
energy delivery schedule obtained from this formulation may not
be realizable. The schedule obtained is generally different from
what is implemented. In this paper, feasible energy delivery is
embedded in SCGS model and power outputs of thermal units are
formulated as piece-wise linear functions rather than step
functions. The schedule obtained from the new formulation is
deliverable in terms of energy and precise ramping process for
implementing the energy schedule is also obtainable. A
mixed-integer linear programming (MILP) method is applied to
solve the problem with the new formulation and numerical testing
is performed for a six-bus system and an IEEE 118-bus system.
The testing results and primary analysis show that the new
formulation is valid.