Demonstration of HVAC chiller control for power grid frequency regulation—Part 1: Controller development and experimental results

Abstract

Secondary frequency regulation is a necessary electric grid ancillary service that balances electric power system supply and demand on short time intervals of seconds to minutes. HVAC chillers may be well positioned to provide secondary frequency regulation as a demand side resource. This article describes the experimental development and performance of a practical controller that modifies chiller power demand to provide secondary frequency regulation. Chiller characteristics are identified through testing of a 200-ton (703-kWth) chiller serving a commercial building in Boston. Appropriate control strategies are subsequently determined. Controller demonstrations using standard electric system operator test routines show the chiller power response to exceed qualification requirements while providing up to ±25% of chiller nameplate power in secondary frequency regulation capability. The controller is further demonstrated to provide secondary frequency regulation continuously for several hours, during which building cooling load changes significantly. The companion article (Su and Norford 2015) discussed the experimental results and assesses the applicability of similar chiller control strategies for broader deployment in other buildings.