HVAC system using model predictive control with distributed low-level airside optimization

A method for optimizing energy cost in a building HVAC system including an airside system having a plurality of airside subsystems, wherein the plurality of airside subsystems receive a working fluid from a shared waterside system comprising waterside HVAC equipment, the method comprising:

• coordinating operation of the plurality of airside subsystems to manage peak demand by performing a high-level optimization at a high-level model predictive controller to generate an airside subsystem energy target for each of the plurality of airside subsystems;
• providing the airside subsystem energy targets from the high-level model predictive controller to a plurality of low-level airside model predictive controllers, each of the low-level airside model predictive controllers corresponding to one of the plurality of airside subsystems;
• performing a low-level optimization at each of the low-level airside model predictive controllers to generate airside temperature setpoints for the corresponding airside subsystem subject to a constraint based on the airside subsystem energy target for the corresponding airside subsystem;
• and
• operating airside HVAC equipment in each of the plurality of airside subsystems in accordance with the airside temperature setpoints.

A heating, ventilation, or air conditioning (HVAC) system for a building, the HVAC system comprising:

• an airside system having a plurality of airside subsystems, each airside subsystem comprising airside HVAC equipment configured to provide heating or cooling to the airside subsystem, wherein the plurality of airside subsystems receive a working fluid from a shared waterside system comprising waterside HVAC equipment;
• a first model predictive controller configured to coordinate and stagger operation of the plurality of airside subsystems by performing a first mathematical operation to generate an airside subsystem energy target for each of the plurality of airside subsystems;
• a plurality of second model predictive controllers, each corresponding to one of the airside subsystems and configured to:
• receive the airside subsystem energy target for the corresponding airside subsystem from the first model predictive controller;
• perform a second mathematical operation to generate airside temperature setpoints for the corresponding airside subsystem using the airside subsystem energy target as a constraint on the second mathematical operation;
• wherein each of the plurality of second model predictive controllers is configured to control the airside HVAC equipment of the corresponding airside subsystem in accordance with the airside temperature setpoints for the corresponding airside subsystem.