Variable refrigerant flow system with multi-level model predictive control

A method for optimizing energy cost in a variable refrigerant flow (VRF) system including an outdoor subsystem and a plurality of indoor subsystems, the method comprising:

• performing a high-level optimization at a high-level model predictive controller to generate an optimal indoor subsystem load profile for each of the plurality of indoor subsystems, wherein the optimal indoor subsystem load profiles optimize the energy cost;
• providing the optimal indoor subsystem load profiles from the high-level model predictive controller to a plurality of low-level indoor model predictive controllers, each of the low-level indoor model predictive controllers corresponding to one of the plurality of indoor subsystems;
• performing a low-level optimization at each of the low-level indoor model predictive controllers to generate optimal indoor setpoints for one or more indoor VRF units of the corresponding indoor subsystem using the optimal indoor subsystem load profile for the corresponding indoor subsystem;
• and
• using the optimal indoor setpoints to operate the indoor VRF units in each of the plurality of indoor subsystems.

A variable refrigerant flow (VRF) system comprising:

• a plurality of indoor subsystems, each indoor subsystem comprising one or more indoor VRF units;
• an outdoor subsystem comprising one or more outdoor VRF units;
• a high-level model predictive controller configured to perform a high-level optimization to generate an optimal indoor subsystem load profile for each of the plurality of indoor subsystems, wherein the optimal indoor subsystem load profiles optimize energy cost;
• and
• a plurality of low-level indoor model predictive controllers, each corresponding to one of the indoor subsystems and configured to perform a low-level optimization to generate optimal indoor setpoints for the indoor VRF units of the corresponding indoor subsystem using the optimal indoor subsystem load profile for the corresponding indoor subsystem.