Central plant control system with linear solver for computation reduction

Patent metadata

Field	Value
Publication number	US-10558178-B2
Application number	US-201816039076-A
Country	US
Kind code	B2
Filing date	Jul 18, 2018
Priority date	Jul 27, 2017
Publication date	Feb 11, 2020
Grant date	Feb 11, 2020

Abstract

Systems and methods for predicting a plurality of thermodynamic states of a plurality of heat, ventilation, and air conditioning (HVAC) devices of an energy plant are disclosed. The system includes a processor and a non-transitory computer readable medium storing instructions when executed causing the processor to: obtain plant netlist data describing the plurality of HVAC devices of the energy plant and connections of the plurality of HVAC devices to corresponding nodes; identify, from the first reduced subset, a second reduced subset of the plurality of thermodynamic states to be predicted by propagating a known value of the plurality of thermodynamic states using a linear solver; predict the second reduced subset of the plurality of thermodynamic states using a non-linear solver; and determine the plurality of thermodynamic states of the energy plant at the plurality of nodes based on the predicted second reduced subset of the plurality of thermodynamic states.

First claim

What is claimed is:

1. A controller for an energy plant, the controller comprising:
a processing circuit comprising a processor and memory storing instructions executed by the processor, the processing circuit configured to:
obtain plant netlist data describing a plurality of heat, ventilation, and air conditioning (HVAC) devices of the energy plant and connections of the plurality of HVAC devices to corresponding nodes, each HVAC device configured to operate according to a corresponding operating parameter,
identify, from a plurality of thermodynamic states of the energy plant at a plurality of nodes, a first reduced subset of the plurality of thermodynamic states to be predicted based on the connections of the plurality of HVAC devices,
identify, from the first reduced subset, a second reduced subset of the plurality of thermodynamic states to be predicted by propagating a known value of the plurality of thermodynamic states using a linear solver,
predict the second reduced subset of the plurality of thermodynamic states using a non-linear solver,
determine the plurality of thermodynamic states of the energy plant at the plurality of nodes based on the predicted second reduced subset of the plurality of thermodynamic states,
determine a set of operating parameters of the plurality of HVAC devices based on the plurality of thermodynamic states of the energy plant at the plurality of nodes, and
operate the plurality of HVAC devices according to the set of operating parameters.

2. The controller of claim 1 , wherein the processing circuit is configured to:
generate an incidence matrix indicating the connections of the plurality of HVAC devices,
obtain an augmented matrix indicating linear relationships of the first reduced subset of the plurality of thermodynamic states, and
obtain an occurrence matrix indicating non-linear relationships of the first reduced subset of the plurality of thermodynamic states.

3. The controller of claim 2 , wherein a row of the augmented matrix corresponds to a number of the linear relationships and a column of the augmented matrix corresponds to a corresponding unknown value of the first reduced subset of the plurality of thermodynamic states.

4. The controller of claim 3 , wherein the processing circuit is configured to:
perform a PLU factorization on the incidence matrix to obtain a permutation matrix of the incidence matrix, the permutation matrix indicating rows in a sequential order to be solved by the linear solver, and
determine whether at least one of the first reduced subset of the plurality of thermodynamic states is predictable using the linear solver based on the augmented matrix.

5. The controller of claim 4 , wherein the processing circuit is configured to:
predict a predictable unknown value of the first reduced subset of the plurality of thermodynamic states using the linear solver, in response to determining that the at least one of the first reduced subset of the plurality of thermodynamic states is predictable based on the augmented matrix, and
determine whether an additional one of the first reduced subset of the plurality of thermodynamic states is predictable using the linear solver based on the augmented matrix.

6. The controller of claim 4 , wherein the processing circuit is configured to:
determine whether at least one of the first reduced subset of the plurality of thermodynamic states is predictable using the linear solver based on the occurrence matrix, in response to determining that no remaining unknown value of the first reduced subset of the plurality of thermodynamic states is predictable based on the augmented matrix.

7. The controller of claim 6 , wherein the processing circuit is configured to:
predict a predictable unknown value of the first reduced subset of the plurality of thermodynamic states using the linear solver, in response to determining that the at least one of the first reduced subset of the plurality of thermodynamic states is predictable based on the occurrence matrix, and
determine whether an additional one of the first reduced subset of the plurality of thermodynamic states is predictable using the linear solver based on the augmented matrix.

8. The controller of claim 6 , wherein the processing circuit is configured to:
predict an unknown value of the first reduced subset of the plurality of thermodynamic states based on system level relationships of the plurality of HVAC devices, the second reduced subset comprising remaining unknown values of the first reduced subset of the plurality of thermodynamic states and excluding predicted values of the first reduced subset.

9. The controller of claim 1 , wherein the second reduced subset of the plurality of thermodynamic states is iteratively predicted by propagating the known value of the plurality of thermodynamic states using the linear solver.

10. A non-transitory computer readable medium storing instructions to operate an energy plant, the instructions when executed by one or more processors cause the one or more processors to:
obtain plant netlist data describing a plurality of heat, ventilation, and air conditioning (HVAC) devices of the energy plant and connections of the plurality of HVAC devices to corresponding nodes, each HVAC device configured to operate according to a corresponding operating parameter;
identify, from a plurality of thermodynamic states of the energy plant at a plurality of nodes, a first reduced subset of the plurality of thermodynamic states to be predicted based on the connections of the plurality of HVAC devices;
identify, from the first reduced subset, a second reduced subset of the plurality of thermodynamic states to be predicted by propagating a known value of the plurality of thermodynamic states using a linear solver;
predict the second reduced subset of the plurality of thermodynamic states using a non-linear solver;
determine the plurality of thermodynamic states of the energy plant at the plurality of nodes based on the predicted second reduced subset of the plurality of thermodynamic states;
determine a set of operating parameters of the plurality of HVAC devices based on the plurality of thermodynamic states of the energy plant at the plurality of nodes; and
operate the plurality of HVAC devices according to the set of operating parameters.

11. The non-transitory computer readable medium of claim 10 , further comprising instructions when executed by the one or more processors cause the one or more processors to:
generate an incidence matrix indicating the connections of the plurality of HVAC devices;
obtain an augmented matrix indicating linear relationships of the first reduced subset of the plurality of thermodynamic states; and
obtain an occurrence matrix indicating non-linear relationships of the first reduced subset of the plurality of thermodynamic states.

12. The non-transitory computer readable medium of claim 11 , wherein a row of the augmented matrix corresponds to a number of the linear relationships and a column of the augmented matrix corresponds to a corresponding unknown value of the first reduced subset of the plurality of thermodynamic states.

13. The non-transitory computer readable medium of claim 12 , further comprising instructions when executed by the one or more processors cause the one or more processors to:
perform a PLU factorization on the incidence matrix to obtain a permutation matrix of the incidence matrix, the permutation matrix indicating rows in a sequential order to be solved by the linear solver; and
determine whether at least one of the first reduced subset of the plurality of thermodynamic states is predictable

Assignees

• Johnson Controls Tech Co

Inventors

• Willmott Graeme
• Asmus Matthew J

Classifications

• G05B2219/2642

  Domotique, domestic, home control, automation, smart house · CPC title

• F24F11/64 Primary

  using pre-stored data · CPC title

• G06F17/10

  Complex mathematical operations {(function generation by table look-up G06F1/03; evaluation of elementary functions by calculation G06F7/544)} · CPC title

• F24F2140/00

  Control inputs relating to system states · CPC title

• F24F11/46

  Improving electric energy efficiency or saving · CPC title