Low level central plant optimization

Patent metadata

Field	Value
Publication number	US-10101731-B2
Application number	US-201514634615-A
Country	US
Kind code	B2
Filing date	Feb 27, 2015
Priority date	May 1, 2014
Publication date	Oct 16, 2018
Grant date	Oct 16, 2018

Abstract

Systems and methods for low level central plant optimization are provided. A controller for the central plant uses binary optimization to determine one or more feasible on/off configurations for equipment of the central plant that satisfy operating constraints and meet a thermal energy load setpoint. The controller determines optimum operating setpoints for each feasible on/off configuration and generates operating parameters including at least one of the feasible on/off configurations and the optimum operating setpoints. The operating parameters optimize an amount of energy consumed by the central plant equipment. The controller outputs the generated operating parameters via a communications interface for use in controlling the central plant equipment.

First claim

What is claimed is:

1. A controller for a central plant having a plurality of subplants that serve thermal energy loads of a building or building system, the controller comprising:
a processing circuit comprising a processor and memory, wherein the processing circuit is configured to identify a thermal energy load setpoint for a subplant of the central plant, wherein the thermal energy load setpoint is generated by a high level optimization that determines optimum thermal energy load setpoints for each of the plurality of subplants by optimally distributing a predicted thermal energy load for the building across the plurality of subplants;
a low level optimization module comprising a binary optimization module of the processing circuit configured to use binary optimization to determine one or more feasible on/off configurations for equipment of the subplant to achieve the thermal energy load setpoint generated by the high level optimization;
the low level optimization module comprising a setpoint evaluator module of the processing circuit configured to determine optimum operating setpoints for the subplant equipment for each feasible on/off configuration;
the low level optimization module configured to generate a resource consumption curve for the subplant by optimizing an amount of resource consumption by the subplant for several different combinations of thermal energy load and weather conditions, the resource consumption curve indicating a minimum amount of resource consumption by the subplant as a function of a thermal energy load on the subplant;
a subplant control module of the processing circuit configured to generate operating parameters for the subplant equipment, the operating parameters comprising at least one of the feasible on/off configurations and the optimum operating setpoints; and
a communications interface coupled to the processing circuit and configured to output the generated operating parameters for use in controlling the subplant equipment.

2. The controller of claim 1 , further comprising a constraints evaluator module configured to identify applicable constraints for the subplant equipment;
wherein each feasible on/off configuration satisfies the applicable constraints and is estimated to result in the subplant equipment meeting the thermal energy load setpoint.

3. The controller of claim 1 , wherein the binary optimization module uses a branch and bound method to determine the one or more feasible on/off configurations.

4. The controller of claim 1 , wherein the setpoint evaluator module determines the optimum operating setpoints using a nonlinear optimization that minimizes an amount of power consumed by the subplant equipment.

5. The controller of claim 1 , wherein the setpoint evaluator module is configured to:
estimate an amount of power consumed by each feasible on/off configuration of the subplant equipment at the optimum operating setpoints; and
identify which of the feasible on/off configurations is estimated to result in a lowest amount of power consumed by the subplant equipment at the optimum operating setpoints.

6. A method for controlling a central plant having a plurality of subplants that serve thermal energy loads of a building or building system, the method comprising:
identifying, by a processing circuit of a controller for the central plant, a thermal energy load setpoint for a subplant of the central plant, wherein the thermal energy load setpoint is generated by a high level optimization that determines optimum thermal energy load setpoints for each of the plurality of subplants by optimally distributing a predicted thermal energy load for the building across the plurality of subplants;
using, by a binary optimization module of the processing circuit, binary optimization to determine one or more feasible on/off configurations for equipment of the subplant to achieve the thermal energy load setpoint generated by the high level optimization;
generating a resource consumption curve for the subplant by optimizing an amount of resource consumption by the subplant for several different combinations of thermal energy load and weather conditions, the resource consumption curve indicating a minimum amount of resource consumption by the subplant as a function of a thermal energy load on the subplant;
determining, by a setpoint evaluator module of the processing circuit, optimum operating setpoints for the subplant equipment for each feasible on/off configuration;
generating, by a subplant control module of the processing circuit, operating parameters for the subplant equipment, the operating parameters comprising at least one of the feasible on/off configurations and the optimum operating setpoints; and
outputting the generated operating parameters via a communications interface coupled to the processing circuit for use in controlling the subplant equipment.

7. The method of claim 6 , further comprising:
identifying applicable constraints for the subplant equipment;
wherein each feasible on/off configuration satisfies the applicable constraints and is estimated to result in the subplant equipment meeting the thermal energy load setpoint.

8. The method of claim 6 , wherein determining the one or more feasible on/off configurations comprises using a branch and bound method.

9. The method of claim 6 , wherein determining the optimum operating setpoints comprises using a nonlinear optimization that minimizes an amount of power consumed by the subplant equipment.

10. The method of claim 6 , further comprising:
estimating an amount of power consumed by each feasible on/off configuration of the subplant equipment at the optimum operating setpoints; and
identifying which of the feasible on/off configurations is estimated to result in a lowest amount of power consumed by the subplant equipment at the optimum operating setpoints.

11. A method for determining optimum operating parameters for equipment of a central plant that serves thermal energy loads of a building or building system, the method comprising:
identifying, by a controller for the central plant, a thermal energy load setpoint for a subplant of the central plant, wherein the thermal energy load setpoint is generated by a high level optimization that determines optimum thermal energy load setpoints for each of a plurality of subplants of the central plant by optimally distributing a predicted thermal energy load for the building across the plurality of subplants;
initializing, by the controller for the central plant, a database of possible solutions and a database of feasible solutions that achieve the thermal energy load setpoint generated by the high level optimization;
generating, by the controller, a resource consumption curve for the subplant by optimizing an amount of resource consumption by the subplant for several different combinations of thermal energy load and weather conditions, the resource consumption curve indicating a minimum amount of resource consumption by the subplant as a function of a thermal energy load on the subplant;
retrieving, by the controller, a branch from the database of possible solutions, the branch comprising a specified operating status for one or more devices of the equipment of the central plant;
determining, by the controller, whether the branch satisfies applicable constraints for the equipment of the central plant using the specified operating status;
adding, by the controller, the branch to the database of feasible solutions in response to a determination that the branch satisfies the applicable constraints; and
generating, by the controller, operating parameters for the equipment of the central plant, the operating parameters comprising the oper

Assignees

• Johnson Controls Tech Co

Inventors

• Asmus Matthew J
• Turney Robert D

Classifications

• G05B2219/2639

  Energy management, use maximum of cheap power, keep peak load low · CPC title

• G05B19/418 Primary

  Total factory control, i.e. centrally controlling a plurality of machines, e.g. direct or distributed numerical control [DNC], flexible manufacturing systems [FMS], integrated manufacturing systems [IMS] or computer integrated manufacturing [CIM] · CPC title

• G05B15/02

  electric · CPC title

• G06Q50/06

  Energy or water supply · CPC title

• G05B13/048

  using a predictor · CPC title