  This paper proposes a cooperative game theory-based under-frequency load
shedding (UFLS) approach for frequency stability and control in power systems.
UFLS is a crucial factor for frequency stability and control especially in
power grids with high penetration of renewable energy sources and restructured
power systems. Conventional UFLS methods, most of which are off-line, usually
shed fixed amounts of predetermined loads based on a predetermined schedule
which can lead to over or under curtailment of load. This paper presents a
co-operative game theory-based two-stage strategy to effectively and precisely
determine locations and amounts of loads to be shed for UFLS control. In the
first stage, the total amount of loads to be shed, also referred to as deficit
in generation or the disturbance power, is computed using the initial rate of
change of frequency (ROCOF) referred to the equivalent inertial center. In the
second stage, the Shapley value, one of the solution concepts of cooperative
game theory, is used to determine load shedding amounts and locations. The
proposed method is implemented on the reduced 9-bus 3-machine Western
Electricity Coordinating Council (WECC) system and simulated on Real-time
Digital Simulators (RTDS). The results show that the proposed UFLS approach can
effectively return the system to normal state after disturbances.
