This work proposes a novel method based on compressive sensing homotopy to dynamically track power line parameters with voltage phasor angle data from phasor measurement units (PMUs). In the literature, compressive sensing has already been successfully applied to locate multiple fault lines in power systems. Our solution substantially extends this work to the case where power line parameters are to be tracked in real time using phasor angle data from a subset of all buses. The new method offers a better performance both in locating the error lines and tracking the changes of line impedances.