Model predictive control for air to water heat pump in context of explicit flexibility: From design to hardware in the loop experiment

Building electrification through heat pumps and renewable energies deployment have pushed for a growing interest in leveraging building flexibility to support the grid. To do so, advanced control strategies for heat pumps specifically designed to address flexibility are required. In that context, this study presents the development of a flexibility-focused controller for heat pumps to meet explicit demand response schemes especially relying on shutdown orders. The primary objective is to enhance the response of heat pumps to the grid orders while maintaining safe and efficient HP operations and suitable user comfort. To achieve this goal, a Model Predictive Control (MPC) framework is developed and combined with additional expert Rule-Based Control (RBC) rules. The controller is then tested on a Hardware-in-the-Loop (HIL) test bench. The tests demonstrate significant improvements in energy management by reducing consumption by 16% as well as reducing discomfort degree-hours by 75% compared to baseline control over the course of 4 winter days. Finally, this study highlights that in order not to degrade HP performance after a shutdown order, it is preferable to maintain standby electricity consumption for immediate compressor availability. This enables a significant mitigation of rebound effects after the shutdown period.