Low-frequency power-grid ancillary services from commercial building HVAC systems

With the introduction of volatile renewable energy sources into the grid, the need for inexpensive ancillary service increases. We propose a method to provide ancillary service by using the flexibility of demand in commercial building HVAC (Heating, Ventilation, Air-Conditioning) systems. In particular, we show how a regulation command transmitted by a balancing authority can be tracked by varying the cooling demand in commercial buildings in real-time. A key idea here is the bandwidth limitation of the regulation signal, which allows the building´s HVAC system to provide this service with little effect on the indoor climate. The proposed control scheme can be applied on any building with a VAV (Variable Air Volume) system and on-site chiller(s). Simple calculations show that the commercial buildings in the U.S. can provide 47 GW of regulation reserves in the frequency band f ∈ [1=(60 min);1=(3 min)] with virtually no change in the indoor climate, while meeting current ISO/RTO standards for regulation.