Central plant control system with setpoints modification based on physical constraints

Patent metadata

Field	Value
Publication number	US-12000608-B2
Application number	US-201816046971-A
Country	US
Kind code	B2
Filing date	Jul 26, 2018
Priority date	Jul 27, 2017
Publication date	Jun 4, 2024
Grant date	Jun 4, 2024

Abstract

Disclosed herein are a system, method, and non-transitory computer readable medium for operating an energy plant. In one aspect, a system determines a ratio of flow rates between devices of the energy plant connected in parallel with each other in a branch. The system generates a candidate set of operating parameters of the devices according to the ratio of flow rates. The system predicts thermodynamic states of the devices operating according to the candidate set of operating parameters. The system determines whether the predicted thermodynamic states satisfy constraints of the devices. The system determines whether the predicted thermodynamic states satisfy a target thermal energy load of the branch based on the ratio of the flow rates. The system operates the energy plant according to the candidate set of operating parameters, in response to determining that the predicted thermodynamic states satisfy the constraints and the target thermal energy load.

First claim

What is claimed is:

1. A controller for an energy plant including heating, ventilation, air conditioning (HVAC) devices, the controller comprising:
a processing circuit comprising a processor and memory storing instructions executed by the processor, the processing circuit configured to:
determine flow rates of gas or liquid through a plurality of the HVAC devices of the energy plant connected in parallel with each other in a branch such that outputs of the plurality of the HVAC devices combine to form a combined output of the branch;
use the flow rates and a constraint on the combined output of the branch to generate a candidate set of operating parameters indicating target thermodynamic states other than flow rate of the outputs of the plurality of the HVAC devices, the candidate set of operating parameters predicted to result in the combined output of the branch having a thermodynamic state other than flow rate that satisfies the constraint on the combined output of the branch when the outputs of the plurality of the HVAC devices combine according to the flow rates to form the combined output of the branch; and
operate the energy plant according to the candidate set of operating parameters by controlling the plurality of the HVAC devices to produce the outputs using the target thermodynamic states indicated by the candidate set of operating parameters.

2. The controller of claim 1 , wherein:
the outputs of the plurality of the HVAC devices comprise heated or chilled fluids supplied by the plurality of the HVAC devices;
the candidate set of operating parameters indicate target supply temperatures for the heated or chilled fluids;
the combined output comprises a combined heated or chilled fluid formed by combining the heated or chilled fluids generated by the plurality of the HVAC devices; and
the constraint indicates a target temperature for the combined heated or chilled fluid.

3. The controller of claim 1 , wherein generating the candidate set of operating parameters comprises:
predicting thermal energy loads of the plurality of the HVAC devices predicted to result from operating the energy plant according to the candidate set of operating parameters; and
adjusting the candidate set of operating parameters to reduce a difference between the predicted thermal energy loads and target thermal energy loads for the plurality of the HVAC devices.

4. The controller of claim 1 , wherein generating the candidate set of operating parameters comprises:
predicting thermal energy loads of the plurality of the HVAC devices predicted to result from operating the energy plant according to the candidate set of operating parameters; and
adjusting the candidate set of operating parameters such that a sum of the predicted thermal energy loads is substantially equal to a target thermal energy load of the branch.

5. The controller of claim 1 , wherein determining the flow rates through the plurality of the HVAC devices comprises:
obtaining hydraulic resistance values for the plurality of the HVAC devices; and
calculating, for each HVAC device of the plurality of the HVAC devices, a flow rate ratio based on a hydraulic resistance value for the HVAC device and a summation of the hydraulic resistance values for the plurality of the HVAC devices.

6. The controller of claim 4 , wherein the processing circuit is configured to determine whether the sum of the predicted thermal energy loads of the plurality of the HVAC devices is substantially equal to the target thermal energy load based on a ratio of the flow rates and outlet temperatures of liquid or gas from the plurality of the HVAC devices.

7. The controller of claim 1 , wherein the processing circuit is configured to generate the candidate set of operating parameters indicating the outputs of the plurality of the HVAC devices by:
generating a matrix including:
a first element associated with a first HVAC device of the plurality of the HVAC devices,
a second element associated with a second HVAC device of the plurality of the HVAC devices, the first element and the second element disposed in a diagonal direction of the matrix,
a third element equal to a negative of the first element, and
a fourth element equal to a negative of the second element, the third element and the fourth element disposed in a column direction of the matrix.

8. The controller of claim 7 , wherein the processing circuit is configured to generate the candidate set of operating parameters indicating the outputs of the plurality of the HVAC devices by:
generating a first vector including outlet temperatures of liquid or gas from the plurality of the HVAC devices;
generating a second vector including thermal energy loads of the plurality of the HVAC devices; and
performing a least squares optimization of the matrix, the first vector, and the second vector to obtain the candidate set of operating parameters.

9. A method for an energy plant including heating, ventilation, air conditioning (HVAC) devices, the method including:
determining flow rates of gas or liquid through a plurality of the HVAC devices of the energy plant connected in parallel with each other in a branch such that outputs of the plurality of the HVAC devices combine to form a combined output of the branch;
using the flow rates and a constraint on the combined output of the branch to generate a candidate set of operating parameters indicating target thermodynamic states other than flow rate of the outputs of the plurality of the HVAC devices, the candidate set of operating parameters predicted to result in the combined output of the branch having a thermodynamic state other than flow rate that satisfies the constraint on the combined output of the branch when the outputs of the plurality of the HVAC devices combine according to the flow rates to form the combined output of the branch; and
operating the energy plant according to the candidate set of operating parameters by controlling the plurality of the HVAC devices to produce the outputs using the target thermodynamic states indicated by the candidate set of operating parameters.

10. The method of claim 9 , wherein:
the outputs of the plurality of the HVAC devices comprise heated or chilled fluids supplied by the plurality of the HVAC devices;
the candidate set of operating parameters indicate target supply temperatures for the heated or chilled fluids;
the combined output comprises a combined heated or chilled fluid formed by combining the heated or chilled fluids generated by the plurality of the HVAC devices; and
the constraint indicates a target temperature for the combined heated or chilled fluid.

11. The method of claim 9 , generating the candidate set of operating parameters comprises:
predicting thermal energy loads of the plurality of the HVAC devices predicted to result from operating the energy plant according to the candidate set of operating parameters; and
adjusting the candidate set of operating parameters to reduce a difference between the predicted thermal energy loads and target thermal energy loads for the plurality of the HVAC devices.

12. The method of claim 9 , wherein generating the candidate set of operating parameters comprises:
predicting thermal energy loads of the plurality of the HVAC devices predicted to result from operating the energy plant according to the candidate set of operating parameters; and
adjusting the candidate set of operating parameters such that a sum of predicted thermal energy loads is substantially equal to a target thermal energy load of the branch.

13. The method of claim 9 , wherein determining the flow rates through the plurality of the HVAC

Assignees

• Johnson Controls Tech Co
• Tyco Fire & Security Gmbh

Inventors

• Willmott Graeme
• Fread Jared W
• Asmus Matthew J

Classifications

• F24F11/49 Primary

  ensuring correct operation, e.g. by trial operation or configuration checks · CPC title

• F24F11/58

  using Internet communication · CPC title

• F24F11/64

  using pre-stored data · CPC title

• F24F11/65

  for selecting an operating mode · CPC title

• G05B13/042

  in which a parameter or coefficient is automatically adjusted to optimise the performance · CPC title