Hierarchical Control of Residential HVAC Units for Primary Frequency Regulation

This paper presents a hierarchical control framework for implementing primary frequency regulation (PFR) by using residential heating, ventilating, and air-conditioning (HVAC) loads. The proposed control system consists of a load aggregator, a central controller, and a group of local controllers. The load aggregator is responsible for managing a population of HVAC loads as a virtual generator to participate in primary reserve market. The central controller dispatches the HVAC loads by assigning a triggering frequency to each HVAC load. A temperature-priority-list method is applied to avoid frequent switching on/off HVAC units when implementing PFR. The local controllers determine the ON/OFF status of HVAC units autonomously based on their triggering frequencies. A self-adjustment algorithm is proposed to correct the error in the assigned triggering frequency by considering minimum ON/OFF time of HVAC units. The proposed control framework can significantly reduce the communication needs. The simulation results indicate that by adopting the proposed control framework, one can dispatch HVAC units more efficiently at the central control level while achieve fast response at the local control level.