We present a new methodology to identify if forced oscillation (FO) sources are located in excitation systems or turbine governors. In this context, we propose to harness the information that dynamic state estimation (DSE) provides to be able to apply a dissipating energy flow (DEF) method. Measurements from phasor measurement units (PMUs) are used to estimate the internal states of different generators connected to the same bus. Using these estimations, we compute energy functions for the mechanical control loop and for the excitation control loop to determine where the FO was originated. Simulated signals from the IEEE-NASPI Oscillation Source Location (OSL) Contest are used to show that our proposal provides an online systematic methodology for identification and location of power systems forced oscillations, even when current measurements of the generator causing the FO are missing. •To introduce a new procedure capable of identifying forced oscillations.•The control loop where the forced oscillation was originated can be identified.•Useful for scenarios with a limited number of phasor current measurements.•The forced oscillations can be detected and identified in tens of seconds.•To provide a robustness analysis for the entire identification procedure.