Proposed a novel control methodology to modulate the aggregated power of a population of heterogeneous end-use loads to follow desired power modulation signals Applied proposed control methodology for end-use loads to provide two different grid services Frequency regulation Damping of inter-area oscillations Technical novelties: Novel signal decomposition method to facilitate load controller design so that heterogeneous end-use loads can provide the service of frequency regulation for the first time (in the literature, only homogeneous end-use loads were considered for frequency regulation) With proposed control approach, it is also for the first time that end-use loads can damp inter-area oscillations for improving grid reliability (in the literature, only transmission-level control was considered)