Controlling an HVAC system in association with a demand-response event with an intelligent network-connected thermostat

Patent metadata

Field	Value
Publication number	US-9810442-B2
Application number	US-201313866635-A
Country	US
Kind code	B2
Filing date	Apr 19, 2013
Priority date	Mar 15, 2013
Publication date	Nov 7, 2017
Grant date	Nov 7, 2017

Abstract

Apparatus, systems, methods, and related computer program products for carrying out a demand response (DR) event via an intelligent, network-connected thermostat associated with a structure. The systems disclosed include an energy management system in operation with an intelligent, network-connected thermostat located at a structure. The thermostat is operable to control an HVAC system. 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 comprising a combination of a first factor representative of a total energy consumption during the DR event period, a second factor representative of a metric of occupant discomfort, and a third factor representative of deviations of a rate of energy consumption over the DR event period.

First claim

What is claimed is:

1. A method of carrying out a demand response (DR) event by an intelligent, network-connected thermostat associated with a structure, the method comprising:
identifying a DR event that defines a DR event period;
accessing a plurality of parameter sets;
generating candidate setpoint schedules during the DR event for the plurality of parameter sets;
simulating each of the candidate setpoint schedules using a thermodynamic model of how the structure responds to a heating, ventilation, and air conditioning (HVAC) system;
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, the cost function comprising a combination of:
a first factor representative of a total energy consumption of the HVAC system during the DR event period;
a second factor representative of a metric of occupant discomfort in the structure; and
a third factor representative of deviations of a rate of energy consumption of the HVAC system from an equalized rate of energy consumption of the HVAC system over the DR event period such that the rate of energy consumption by the HVAC system over the DR event period can be made substantially constant;

selecting an optimal predicted indoor temperature profile or HVAC duty cycle schedule that minimizes the cost function; and
controlling the HVAC system 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, including:
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 parameter set 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 the deviations of the 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 the pre-DR event period.

6. The method of claim 1 , wherein the thermodynamic model of how the structure responds to the HVAC system is continuously updated.

7. An intelligent network-connected thermostat for controlling an operation of an HVAC system in a structure, the thermostat comprising:
HVAC control circuitry operable to actuate one or more elements of the HVAC system;
one or more sensors for measuring characteristics of a smart home environment; and
a processor coupled to the HVAC control circuitry and the one or more sensors and operable to cause the thermostat to perform operations including:
identifying a DR event that defines a DR event period;
accessing a plurality of parameter sets;
generating candidate setpoint schedules during the DR event for the plurality of parameter sets;
simulating each of the candidate setpoint schedules using a thermodynamic model of how the structure responds to the HVAC system;
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, the cost function comprising a combination of:
a first factor representative of a total energy consumption of the HVAC system during the DR event period;
a second factor representative of a metric of occupant discomfort in the structure; and
a third factor representative of deviations of a rate of energy consumption of the HVAC system from an equalized rate of energy consumption of the HVAC system over the DR event period such that the rate of energy consumption by the HVAC system over the DR event period can be made substantially constant; and

selecting an optimal predicted indoor temperature profile or HVAC duty cycle schedule that minimizes the cost function; and
controlling the HVAC system during the DR event period in accordance with the optimal predicted indoor temperature profile or HVAC duty cycle schedule.

8. The thermostat of claim 7 , wherein the processor is further operable to cause the thermostat to perform operations including:
determining whether the HVAC system should be controlled in accordance with a different predicted indoor temperature profile or HVAC duty cycle schedule; and
upon determining that the HVAC system 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 HVAC system in accordance with the new predicted indoor temperature profile or HVAC duty cycle schedule.

9. The thermostat of claim 8 , wherein determining whether the HVAC system 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 thermostat of claim 8 , wherein determining whether the HVAC system 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 structure and comparing the monitored indoor temperature of the structure to a predicted indoor temperature of the structure;
monitoring a state of the HVAC system and comparing the monitored state of the HVAC system to a predicted state of the HVAC system;
monitoring a real-time occupancy of the structure; and
determining whether the optimal predicted indoor temperature profile or HVAC duty cycle schedule fails.

11. The thermostat of claim 8 , wherein identifying a subsequent predicted indoor temperature profile or HVAC duty cycle schedule includes one of:
determining a newly optimized predicted indoor temperature profile or HVAC duty cycle schedule that minimizes the cost function;
determining an original control trajectory; and
determining a default control trajectory.

12. The thermostat of claim 7 , wherein the processor is further operable to cause the thermostat to perform operations including:
monitoring an indoor temperature of the structure;
comparing the monitored indoor temperature of the structure to a predicted indoor temperature of the structure; and
upon determining that the monitored indoor temperature is different from the predicted indoor temperature of the structure by at least a certain amount:
determining a default control trajectory; and
controlling the HVAC system in accordance with the default control trajectory.

13. The thermostat of claim 7 , wherein the processor is further operable to cause the thermostat to perform operations including:
monitoring a state of the HVAC system;
compar

Assignees

• Google Inc

Inventors

• Matsuoka Yoky
• Malhotra Mark
• Minich Allen J
• Stefanski Mark D

Classifications

• F24F11/64 Primary

  using pre-stored data · CPC title

• F24F11/30 Primary

  for purposes related to the operation of the system, e.g. for safety or monitoring · CPC title

• F24F11/006 Primary

  Mechanical Engineering · mapped topic

• G05D23/1905

  associated with tele control · CPC title

• F24F2011/0047

  Mechanical Engineering · mapped topic