Multi‐Range Signal Oscillation Detection – Concepts and Applications Mark Adamiak Zhiying Zhang Ilia Voloh GE Grid Solutions Abstract Oscillations on the power system represent an exchange of real or reactive power between entities on the grid or quantities induced onto the grid or as the result of a resonance. Due to the electromechanical make-up of the grid, oscillations have existed from the beginning power system time. In the beginning, the primary source of oscillations was machine-to-machine hunting – resulting in what is known today as Inter-Area Oscillations. As the power system has grown and expanded into new realms, the sources and frequencies of oscillations have expanded. This paper identifies a set of ranges of sub-synchronous oscillations, introduces a new measurement technique for these oscillations, and identifies possible mitigation strategies. Oscillation Definition Oscillations can be characterized by: • Frequency • Magnitude • Synchro Angle • Damping constant In the example in figure 1, one can see examples of both Positively (Figure 1a) and Negatively (Figure 1b) damped oscillations. The August 10, 1996 Western US system breakup has been attributed to negatively damped electromechanical oscillations on the grid3. Figure 1a Positively Damped Oscillation Figure 1b Negatively Damped Oscillation