Cluster Control of Heterogeneous Thermostatically Controlled Loads Using Tracer Devices

Managing the aggregated demand of large heterogeneous clusters of thermostatically controlled loads (TCLs) is considered a sequential decision-making problem under uncertainty. Recent research indicates that using reduced-order models in combination with a broadcasted control signal offers a viable solution to the tradeoff between computational feasibility, and accurately describing the steady-state and transient cluster response. In this paper, we propose a novel control strategy based on tracer devices, which we define as a limited amount of virtual TCLs that represent the entire cluster of heterogeneous TCLs. These second-order model devices are identified in a nonintrusive manner, and capture both steady-state and transient population dynamics, as well as cluster heterogeneity. Additionally, the dispatch mechanism is included in the optimization, further improving the tracking performance. The parameterizable number of tracer devices enables a covering of the tradeoff domain. Both approaches have been evaluated in two scenarios. In the first small-scale scenario, improvements in price and power deviations are evaluated when using increasing numbers of tracer devices and integrating the dispatch dynamics. Results from the second large-scale scenario show that root mean square dispatch errors can be reduced by more than 10% when integrating the dispatch mechanism in the resulting high-fidelity model.