Patent ID: 8498832

Claim:
A device for assessing and monitoring voltage stability in an electrical power system including a plurality of generators and phasor measurement units, said phasor measurement units adapted to acquire and communicate phasor measurements from various locations on the power system, the device comprising: a communications port adapted to receive the phasor measurements from the phasor measurement units, a predictive reactive power load limit calculator to calculate a reactive power loading margin where the plurality of generators will reach their respective and combined reactive power limits using a small number of power-flow runs, the calculator in communication with the communications port and receiving the phasor measurements, and the calculator adapted to: calculate a predictive generator reactive power sensitivity indicating an anticipated change in generation reactive power output resulting from a predictive change in reactive power load at a specified reactive power load using the phasor measurements, wherein the magnitude of the sensitivity is related to the proximity to a static limit; determine, based on the sensitivity, a load increment used for calculating the specified reactive power load for the next power-flow run, and, when the sensitivity is not less than a threshold, calculate the reactive power loading margin as a difference between the specified reactive power load and a current reactive power load.