Distributed control of thermostatically controlled load aggregators in multi-area power systems

In modern power systems, the high penetration of renewable energy challenges system frequency regulation and stability. In such conditions, the demand-side loads can be aggregated and applied for power system frequency regulation. In this study, a dual-level distributed control framework is proposed for thermostatically controlled load (TCL) aggregators in multi-area load frequency control. In the higher control level, the leader of TCL aggregators in each control area is controlled by local and neighbouring area control errors. In the lower control level, multiple TCL aggregators are coupled via a leader-follower consensus control protocol to track the power reference from the area leader. As a result, the dual-level distributed controlled TCL aggregators can operate together with synchronous generators for frequency regulation in multi-area power systems. The proposed method is validated in a three-area power system under various cyber-physical conditions, including contingency and normal operation conditions, as well as communication failure and delay conditions.