  Inverter Based Generators (IBGs) have been increasing significantly in power
systems. Due to the demanding thermal rating of Power Electronics (PE), their
contribution to the system Short Circuit Current (SCC) is much less than that
from the conventional Synchronous Generators (SGs) thus reducing the system
strength and posing challenges to system protection and stability. This paper
proposes a Unit Commitment (UC) model with SCC constraint in high
IBG-penetrated systems to ensure minimum operation cost while maintaining the
SCC level at each bus in the system. The SCC from synchronous generators as
well as the IBGs are explicitly modeled in the formulation leading to an SCC
constraint involving decision-dependent matrix inverse. This highly nonlinear
constraint is further reformulated into linear form conservatively. The
influence of the SCC constraint on the system operation and its interaction
with the frequency regulation are demonstrated through simulations on IEEE 30-
and 118-bus systems.
