CONTROLLING AN HVAC SYSTEM IN ASSOCIATION WITH A DEMAND-RESPONSE EVENT

• US 20180088605A1
• Filed: 11/07/2017
• Published: 03/29/2018
• Est. Priority Date: 03/15/2013
• Status: Active Grant

• Current Assignee: Google LLC (Alphabet Inc.)
• Original Assignee: Google LLC (Alphabet Inc.)
• Inventors: Matsuoka, Yoky, Malhotra, Mark, Minich, Allen J., Stefanski, Mark D.
• Granted Patent: US 10,718,539 B2
• Time in Patent Office: Days
• CPC Class Codes: F24F 11/30 for purposes related to the operation of the system, e.g. for safety or monitoring
• CPC Class Codes: F24F 11/62 characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
• CPC Class Codes: F24F 11/64 using pre-stored data
• CPC Class Codes: F24F 2120/20 Feedback from users
• CPC Class Codes: F24F 2140/60 Energy consumption
• CPC Class Codes: G05D 23/1904 variable in time
• CPC Class Codes: G05D 23/1905 associated with tele control

Abstract

A control system includes an energy management system in operation with intelligent, network-connected thermostats located in structures. The thermostats are operable to control HVAC systems. Control during a DR event period may be performed based on an optimal control trajectory of the HVAC system, where the control trajectory is optimal in that it minimizes a cost function.

Claims

1. A method of carrying out a demand response (DR) event by a control system, the method comprising:

identifying, by the system, a DR event period for the DR event;

accessing a plurality of parameter sets;

generating candidate setpoint schedules for the DR event period for each of the plurality of parameter sets;

simulating each of the candidate setpoint schedules using a thermodynamic model of how one or more structures respond to one or more heating, ventilation, and air conditioning (HVAC) systems;

generating predicted indoor temperature profiles or HVAC duty cycle schedules for each of the simulated candidate setpoint schedules;

evaluating a cost function for each of the predicted indoor temperature profiles or HVAC duty cycle schedules;

selecting an optimal predicted indoor temperature profile or HVAC duty cycle schedule that minimizes the cost function; and

controlling the one or more HVAC systems during the DR event period in accordance with the optimal predicted indoor temperature profile or HVAC duty cycle schedule.

2. The method of claim 1, further comprising:

determining a setpoint temperature profile over the DR event period by;

calculating a setpoint temperature profile over the DR event period based on an expected indoor temperature trajectory, and

identifying peaks and troughs of the calculated setpoint temperature profile; and

causing setpoint temperatures defined by the setpoint temperature profile to be displayed to a user of the HVAC system.

3. The method of claim 1, wherein each of the plurality of parameter sets comprises:

a first parameter indicative of a temperature-wise offset from a temperature setpoint of an original setpoint schedule; and

a second parameter indicative of a slope of a linear sequence of temperature setpoints passing through a point at the temperature-wise offset from the temperature setpoint of the original setpoint schedule,

wherein the temperature-wise offset and the slope of the linear sequence of temperature setpoints are designed to assist in reducing deviations of a rate of energy consumption over the DR event period.

4. The method of claim 3, wherein each parameter set further comprises a third parameter indicative of a maximum HVAC duty cycle period.

5. The method of claim 3, wherein each parameter set further comprises a fourth parameter indicative of a duration of a pre-DR event period.

6. The method of claim 1, wherein the thermodynamic model is continuously updated.

7. The method of claim 1, wherein the control system comprises a thermostat and a thermostat management server.

8. The method of claim 1, further comprising:

determining whether the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule; and

upon determining that the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule;

identifying a new predicted indoor temperature profile or HVAC duty cycle schedule; and

controlling the one or more HVAC systems in accordance with the new predicted indoor temperature profile or HVAC duty cycle schedule.

9. The method of claim 8, wherein determining whether the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule is performed periodically during the DR event period.

10. The method of claim 8, wherein determining whether the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule includes one or more of:

monitoring an indoor temperature of the one or more structures and comparing the monitored indoor temperature of the one or more structures to a predicted indoor temperature of the one or more structures;

monitoring a state of the one or more HVAC systems and comparing the monitored state of the one or more HVAC systems to a predicted state of the one or more HVAC systems;

monitoring a real-time occupancy of the one or more structures; and

determining whether the optimal predicted indoor temperature profile or HVAC duty cycle schedule fails.

11. A control system for controlling operations of one or more HVAC systems in one or more structures, the control system comprising:

one or more processors; and

one or more memory devices comprising instructions that, when executed by the one or more processors, cause the one or more processors to perform operations comprising;

identifying, by the system, a DR event period for the DR event;

accessing a plurality of parameter sets;

generating candidate setpoint schedules for the DR event period for each of the plurality of parameter sets;

simulating each of the candidate setpoint schedules using a thermodynamic model of how one or more structures respond to one or more heating, ventilation, and air conditioning (HVAC) systems;

generating predicted indoor temperature profiles or HVAC duty cycle schedules for each of the simulated candidate setpoint schedules;

evaluating a cost function for each of the predicted indoor temperature profiles or HVAC duty cycle schedules;

selecting an optimal predicted indoor temperature profile or HVAC duty cycle schedule that minimizes the cost function; and

controlling the one or more HVAC systems during the DR event period in accordance with the optimal predicted indoor temperature profile or HVAC duty cycle schedule.

12. The control system of claim 11, wherein the operations further comprise:

determining a setpoint temperature profile over the DR event period by;

calculating a setpoint temperature profile over the DR event period based on an expected indoor temperature trajectory, and

identifying peaks and troughs of the calculated setpoint temperature profile; and

causing setpoint temperatures defined by the setpoint temperature profile to be displayed to a user of the HVAC system.

13. The control system of claim 11, wherein each of the plurality of parameter sets comprises:

a first parameter indicative of a temperature-wise offset from a temperature setpoint of an original setpoint schedule; and

a second parameter indicative of a slope of a linear sequence of temperature setpoints passing through a point at the temperature-wise offset from the temperature setpoint of the original setpoint schedule,

wherein the temperature-wise offset and the slope of the linear sequence of temperature setpoints are designed to assist in reducing deviations of a rate of energy consumption over the DR event period.

14. The control system of claim 13, wherein each parameter set further comprises a third parameter indicative of a maximum HVAC duty cycle period.

15. The control system of claim 13, wherein each parameter set further comprises a fourth parameter indicative of a duration of a pre-DR event period.

16. The control system of claim 11, wherein the thermodynamic model is continuously updated.

17. The control system of claim 11, wherein the one or more processors and the one or more memory devices are distributed between one or more thermostats and one or more thermostat management servers.

18. The control system of claim 11, wherein the operations further comprise:

determining whether the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule; and

upon determining that the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule;

identifying a new predicted indoor temperature profile or HVAC duty cycle schedule; and

controlling the one or more HVAC systems in accordance with the new predicted indoor temperature profile or HVAC duty cycle schedule.

19. The control system of claim 18, wherein determining whether the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule is performed periodically during the DR event period.

20. The control system of claim 18, wherein determining whether the one or more HVAC systems should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule includes one or more of:

monitoring an indoor temperature of the one or more structures and comparing the monitored indoor temperature of the one or more structures to a predicted indoor temperature of the one or more structures;

monitoring a state of the one or more HVAC systems and comparing the monitored state of the one or more HVAC systems to a predicted state of the one or more HVAC systems;

monitoring a real-time occupancy of the one or more structures; and

determining whether the optimal predicted indoor temperature profile or HVAC duty cycle schedule fails.