  Integration of intermittent renewable energy sources in modern power systems
is increasing very fast. Replacement of synchronous generators with zero-to-low
variable renewables substantially decreases the system inertia. In a large
system, inertia distribution may vary significantly, areas of low inertia are
more susceptible to frequency deviation, posing risks of load shedding and
generation trip. Therefore, it is necessary for operators to evaluate and
quantify the system inertia and its distribution in real time. This paper
proposes a novel synchronized phasor measurement units (PMUs)-based dynamic
system inertia estimation method. The proposed inertia estimation method is
derived using electrical distance and clustering algorithm, which considers the
impact of location of measurements relative to in-feed load and impact of
oscillations. The center of inertia (COI) area and area of low inertia are also
determined during the estimation. Numerical simulations are conducted on the
IEEE 24-bus system with various load profiles using Transient Security Analysis
Tools (TSAT), a core module of the DSATools, which demonstrate the efficacy of
the proposed approach.
