Central plant with coordinated HVAC equipment staging across multiple subplants

Patent metadata

Field	Value
Publication number	US-10190789-B2
Application number	US-201514872074-A
Country	US
Kind code	B2
Filing date	Sep 30, 2015
Priority date	Sep 30, 2015
Publication date	Jan 29, 2019
Grant date	Jan 29, 2019

Abstract

A central plant includes at least a first subplant and a second subplant configured to serve a thermal energy load of a building. A controller for the central plant includes an equipment staging detector configured to detect a staging event for equipment of the second subplant and to determine when the staging event occurs. The controller includes a subplant staging evaluator configured to use input from the equipment staging detector to determine whether a predetermined time period has elapsed since the staging event for the equipment of the second subplant has occurred. The controller includes a subplant staging preventer configured to prevent the first subplant from staging equipment of the first subplant in response to a determination that the predetermined time period has not elapsed since the staging event for the equipment of the second subplant has occurred.

First claim

What is claimed is:

1. A controller for a central plant that includes at least a first subplant and a second subplant configured to serve a thermal energy load of a building, the controller comprising:
a communications interface configured to communicate with the first subplant and the second subplant; and
a processing circuit communicably coupled to the communications interface and comprising a processor and memory, the memory comprising:
an equipment staging detector configured to detect a staging event for equipment of the second subplant and to determine when the staging event occurs;
a subplant staging evaluator configured to use input from the equipment staging detector to determine whether a predetermined time period has elapsed since the staging event for the equipment of the second subplant has occurred;
a subplant staging preventer configured to prevent the first subplant from staging equipment of the first subplant in response to a determination that the predetermined time period has not elapsed since the staging event for the equipment of the second subplant has occurred;
a central plant optimizer configured to perform an optimization process to determine a desired set of the equipment of the first subplant for use in serving the thermal energy load; and
a desired equipment drop detector configured to determine whether the desired set of the equipment of the first subplant has dropped to zero;
wherein the subplant staging preventer is configured to allow the first subplant to stage the equipment of the first subplant in response to a determination that the desired set of the equipment of the first subplant has dropped to zero.

2. The controller of claim 1 , wherein the first subplant and the second subplant are controlled by separate subplant controllers and configured to serve a same type of thermal energy load.

3. The controller of claim 1 , wherein the first subplant is one of a chiller subplant and a heat recovery chiller subplant and the second subplant is the other of the chiller subplant and the heat recovery chiller subplant.

4. The controller of claim 1 , wherein the staging event comprises at least one of activating or deactivating the equipment of the second subplant, changing a load setpoint for the equipment of the second subplant, and changing a capacity of the equipment of the second subplant.

5. The controller of claim 1 , wherein the subplant staging evaluator is further configured to determine whether the first subplant is at steady state and whether the second subplant is at steady state;
wherein the subplant staging preventer is configured to prevent the first subplant from staging the equipment of the first subplant in response to a determination that the first subplant is at steady state and the second subplant is not at steady state.

6. A controller for a central plant that includes at least a first subplant and a second subplant configured to serve a thermal energy load of a building, the controller comprising:
a communications interface configured to communicate with the first subplant and the second subplant; and
a processing circuit communicably coupled to the communications interface and comprising a processor and memory, the memory comprising:
an equipment staging detector configured to detect a staging event for equipment of the second subplant and to determine when the staging event occurs;
a subplant staging evaluator configured to use input from the equipment staging detector to determine whether a predetermined time period has elapsed since the staging event for the equipment of the second subplant has occurred;
a subplant staging preventer configured to prevent the first subplant from staging equipment of the first subplant in response to a determination that the predetermined time period has not elapsed since the staging event for the equipment of the second subplant has occurred; and
a toggle input configured to provide opposite binary inputs for the first and second subplants;
wherein the subplant staging preventer is configured to allow the first subplant to stage the equipment of the first subplant in response to a determination that a binary input for the first subplant has a first binary value;
wherein the subplant staging preventer is configured to prevent the first subplant from staging the equipment of the first subplant in response to a determination that the binary input for the first subplant has a second binary value, opposite the first binary value.

7. The controller of claim 6 , wherein the toggle input is configured to periodically switch the opposite binary inputs for the first and second subplants.

8. The controller of claim 6 , wherein the subplant staging preventer uses the toggle input as an override signal and determines whether to prevent the first subplant from staging the equipment of the first subplant based on the toggle input regardless of whether the predetermined time period has elapsed since the staging event for the equipment of the second subplant has occurred.

9. The controller of claim 6 , wherein the first subplant and the second subplant are controlled by separate subplant controllers and configured to serve a same type of thermal energy load.

10. The controller of claim 6 , wherein the staging event comprises at least one of activating or deactivating the equipment of the second subplant, changing a load setpoint for the equipment of the second subplant, and changing a capacity of the equipment of the second subplant.

11. A method for coordinating equipment staging across a central plant that includes at least a first subplant and a second subplant configured to serve a thermal energy load of a building, the method comprising:
detecting, by a controller for the central plant, a staging event for equipment of the second subplant and determining when the staging event occurs, the controller comprising a communications interface configured to communicate with the first subplant and the second subplant and a processing circuit communicably coupled to the communications interface, the processing circuit comprising a processor and memory;
determining, by the controller, whether a predetermined time period has elapsed since the staging event for the equipment of the second subplant has occurred;
preventing, by the controller, the first subplant from staging equipment of the first subplant in response to a determination that the predetermined time period has not elapsed since the staging event for the equipment of the second subplant has occurred;
performing, by the controller, an optimization process to determine a desired set of the equipment of the first subplant for use in serving the thermal energy load;
determining, by the controller, whether the desired set of the equipment of the first subplant has dropped to zero; and
allowing, by the controller, the first subplant to stage the equipment of the first subplant in response to a determination that the desired set of the equipment of the first subplant has dropped to zero.

12. The method of claim 11 , wherein the first subplant and the second subplant are controlled by separate subplant controllers and configured to serve a same type of thermal energy load.

13. The method of claim 11 , wherein the first subplant is one of a chiller subplant and a heat recovery chiller subplant and the second subplant is the other of the chiller subplant and the heat recovery chiller subplant.

14. The method of claim 11 , wherein the staging event comprises at least one of activating or deactivating the equipment of the second subplant, changing a load setpoint for the equipment of the second subplant, a

Assignees

• Johnson Controls Tech Co

Inventors

• Mueller Jon T
• Carmody Joseph P

Classifications

• G05B15/02 Primary

  electric · CPC title

• F24F11/006 Primary

  Mechanical Engineering · mapped topic

• F24F11/62

  characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values · CPC title

• F24F11/61

  using timers · CPC title

• F24F2140/50

  Load · CPC title