  Poorly damped oscillations pose threats to the stability and reliability of
interconnected power systems. In this work, we propose a comprehensive
data-driven framework for inferring the sources of forced oscillation (FO)
using solely synchrophasor measurements. During normal grid operations,
fast-rate ambient data are collected to recover the impulse responses in the
small-signal regime, without requiring the system model. When FO events occur,
the source is estimated based on the frequency domain analysis by fitting the
least-squares (LS) error for the FO data using the impulse responses recovered
previously. Although the proposed framework is purely data-driven, the result
has been established theoretically via model-based analysis of linearized
dynamics under a few realistic assumptions. Numerical validations demonstrate
its applicability to realistic power systems including nonlinear, higher-order
dynamics with control effects using the IEEE 68-bus system, and the 240-bus
system from the IEEE-NASPI FO source location contest. The generalizability of
the proposed methodology has been validated using different types of
measurements and partial sensor coverage conditions.
