A Phase Model Based Control of Periodic Deferrable Loads in Demand Response Programs

A significant portion of electricity consumed worldwide is used to power thermostatically controlled loads (TCLs) such as air conditioners, refrigerators, and water heaters. Because the short-term timing of operation of such systems is inconsequential as long as their long-run average power consumption is maintained, they are increasingly used in demand response (DR) programs to balance supply and demand on the power grid. Here, we use the phase model representation of TCLs to design and evaluate control policies for modulating the power consumption of aggregated loads with parameter heterogeneity and stochastic drift. In particular, we design a phase model based minimum energy control law that modulates the duty cycle of a TCL in order to reduce its energy consumption. We further demonstrate that the designed control policy can be used to effectively modulate the aggregate power of a heterogeneous TCL population while maintaining load diversity and minimizing power overshoots. More importantly, an acceptable quality of service for the utility customers is maintained. The developed control policy can be used to compensate for the intermittent generation by renewable energy sources (RESs) such as wind and solar by regulating the aggregated load of a TCL ensemble, and hence will facilitate the broader integration of RESs.