  As renewable resources gradually replace conventional generation based
synchronous machines, the dynamics of the modern grid changes significantly and
the system synchronous inertia decreases substantially. This transformation
poses severe challenges for power system stability; for instance, it may lead
to larger initial rate of change of frequency and increase frequency
excursions. However, new opportunities also arise as novelconverter control
techniques, so-called grid-forming strategies, show higher efficiency and
faster response than conventional synchronous generators. They mainly involve
virtual inertia (VI) emulation to mimic the behavior of synchronous machines.
In this study, a state-space model for the power system network is developed
with VI as a frequency regulation method. A reduced model based-norm algorithm
(RMHA) considering the Fiedler mode impact is proposed in this paper to
optimize the allocation of VI devices and improve power system frequency
stability. Finally, case studies conducted on the IEEE 24-bus system
demonstrate the efficacy of the proposed RMHA approach.
