  This paper develops a systematic framework for analyzing how low frequency
forced oscillations propagate in electric power systems. Using this framework,
the paper shows how to mathematically justify the so-called Dissipating Energy
Flow (DEF) forced oscillation source location technique. The DEF's specific
deficiencies are pinpointed, and its underlying energy function is analyzed via
incremental passivity theory. This analysis is then used to prove that there
exists no passivity transformation (i.e. quadratic energy function) which can
simultaneously render all components of a lossy classical power system passive.
The paper goes on to develop a simulation-free algorithm for predicting the
performance of the DEF method in a generalized power system, and it analyzes
the passivity of three non-classical load and generation components. The
proposed propagation framework and performance algorithm are both tested and
illustrated on the IEEE 39-bus New England system and the WECC 179-bus system.
