Patent ID: 8369055
Filing Date: 2013-02-05
Classification: H02H

Abstract:
1. A method of determining out-of-step tripping angle based on the information about the voltage angle at a remote end contained in a swing current, characterized by the following steps: measuring the current and voltage of power system, calculating the superimposed positive sequence current and superimposed positive sequence resistance, determining the change in polarity of superimposed positive sequence current (ΔI), determining change in polarity of superimposed positive sequence resistance (ΔR), comparing change of polarity of the superimposed positive sequence current (ΔI) with the change in polarity of the positive sequence resistance (ΔR), determining recoverable swing when the change of ΔI polarity has changed with the change of ΔR polarity, determining pole slip, indicating non-recoverable swing, when the ΔI polarity has changed whilst ΔR polarity remains unchanged, calculating the correct instant for tripping (I