  The flexible power consumption feature of thermostatically controlled loads
(TCLs) such as heating, ventilation, and air-conditioning (HVAC) systems makes
them attractive targets for demand response (DR). TCLs possess a brief period
where their power utilization can be altered without any significant impact on
customer comfort level. This indicates TCLs are hidden potentials for providing
ancillary services. This paper proposes a novel metric of demand response
support time (DRST) for HVAC enabled demand response and a novel algorithm for
the quantification of such HVAC-DR. The consumers' comfort will not be
compromised with the proposed DRST-based HVAC-DR. Case studies demonstrate its
benefits in terms of cost saving in microgrid day-ahead scheduling and
reduction of forced load shedding during a grid-microgrid tie-line outage
event. This illustrates the reserve potential benefits and the increase of
microgrid reliability when DRST-based HVAC-DR is considered.
