Patent ID: 6476521
Filing Date: 2002-11-05
Classification: H02H,H02J

Abstract:
System protection scheme (SPS) for protection of the integrity of an overall electric power system against poorly damped power oscillations, comprising:a set of at least two system protection terminals, and a communication system interconnecting said at least two system protection terminals, said at least two system protection terminals in turn comprising: a processor unit, and a communication unit connected to said processor unit for communication on said communication system, wherein system protection terminals in a first subset of said set of system protection terminals comprise measurement signal obtaining means connected to said processor unit for collecting measurement signals of measured characteristics of said electric power system, said first subset comprising at least two system protection terminals, said measured characteristics comprising at least one of, time stamped voltage values, time stamped current values, and quantities derivable therefrom, wherein said processor unit in system protection terminals in a second subset of said set of at least two system protection terminals in turn comprises evaluation means for detecting poorly damped power oscillations based on said measured characteristics from at least two of said system protection terminals in said first subset, wherein said evaluation means being arranged for obtaining node angle differences between different locations associated with said system protection terminals of said first subset and for determining at least one of amplitude, frequency and damping of said detected power oscillations from said node angle differences, and wherein said system protection terminals in said second subset further comprising control signal providing means connected to said processor unit for providing control signals to power system actuating units counteracting said poorly damped power oscillations in response to an output of said evaluation means.