Analysis Of November 29, 2005 Western American Oscillation Event

The letter discusses the oscillation event of November 29, 2005 in the western American power system when a 20 MW forced oscillation in Alberta led to 200 MW oscillations on the California-Oregon Inter-tie lines. Using archived synchrophasor data from the event, this letter shows that the large amplitude tie-line oscillations were caused by a resonance between the forced oscillations and the 0.25 Hz inter-area western system mode. Specifically the letter shows that resonance occurred even though the system mode was well-damped during the event because of the oscillation frequency and location of the forced oscillations.