Frequency regulation support from aggregation of air conditioners based on the trigger value local update strategy

As the penetration of renewable energy sources increases, demand side resources like air conditioners (ACs), whose electricity consumptions account for a large share, present remarkable potentials as frequency reserves to maintain the electricity supply-demand balance. This study proposes a hybrid control framework based on a central controller and local controllers, under which air conditioning loads managed by the load aggregator are constructed as a virtual generator for frequency regulation. A well-founded setting and updating method of frequency deviation trigger values in consideration of lock on and off constraints is designed. In the level of the central controller, on the basis of priority lists, the actual droop curve composed of ACs is constructed and the initial frequency deviation trigger values are determined. In the level of the local controllers, on/off states of ACs are switched autonomously according to their trigger values. In order to prevent response power deviations caused by lock on and off constraints, a trigger value local update strategy is developed to adjust the frequency deviation trigger values in the local controllers, which would not increase communication burden between the central controller and local controllers. Simulation studies suggest the effectiveness of the proposed method.