  Load-altering attacks (LAAs) pose a significant threat to power systems with
Internet of Things (IoT)-controllable load devices. This research examines the
detrimental impact of LAAs on the voltage profile of distribution systems,
taking into account the realistic load model with constant impedance Z,
constant current I, and constant power P (ZIP). We derive closed-form
expressions for computing the voltages of buses following LAA by making
approximations to the power flow as well as the load model. We also
characterize the minimum number of devices to be manipulated in order to cause
voltage safety violations in the system. We conduct extensive simulations using
the IEEE-33 bus system to verify the accuracy of the proposed approximations
and highlight the difference between the attack impacts while considering
constant power and the ZIP load model (which is more representative of
real-world loads).
