Patent ID: 7996116
Filing Date: 2011-08-09
Classification: H02J,Y02B,Y04S

Abstract:
1. A method of monitoring voltage stability within an electrical power system, the method comprising the steps of: establishing a voltage stability margin Stability based on an operating characteristic of the power system including calculating: where Z where a) Z L1 and Z L2 are, respectively, initial and final values of the load impedance Z L , b) S being a load apparent power, V being a power system voltage, and Y being the load admittance given by Y=1/Z with Δ=φ c) where φ s is the source equivalent impedance phase angle and φ L is the load phase angle, F=cos [0.5(Δ1+Δ2)], and d) Δ1 and Δ2 are respectively initial and final values of Δ indicating that the power system has become unstable when the voltage stability margin falls below a predetermined value; and initiating dynamic load shedding and/or restoration depending on the voltage stability margin.