Forced oscillation source location via mahalanobis distance with confidence assessment

When the frequency of an external periodic input or a forced oscillation (FO) is close to that of an inter-area mode of the power system, resonance can occur, and the oscillations may be observed over a vast geographical region. This makes it challenging to locate the FO source. This paper analyzes the interactions of a forced oscillation with local and inter-area modes to show that the amplitude and phase of the dynamic response near the source location can differ substantially from those of non-source generators during a forced oscillation event. This concept forms the basis of a novel source location method, implemented using the Mahalanobis distance (MD) to identify the likely source as a statistical outlier among the amplitude and phase responses observed in phasor measurement units at the forced-oscillation frequency. Results from a validated model of the 1996 Western Interconnection system blackout events and a 240-bus Western Electricity Coordinating Council system model, along with comparisons with existing methods, demonstrate the effectiveness of the proposed approach. In addition, a confidence metric is proposed to assess the credibility of the potential FO source suggested by the method.