Water Heater Demand Side Management System

• US 20100004790A1
• Filed: 06/26/2009
• Published: 01/07/2010
• Est. Priority Date: 07/01/2008
• Status: Active Grant

• Current Assignee: Bristol Tennessee Essential Services, Carina Technology, Inc.
• Original Assignee: Carina Technology, Inc.
• Inventors: O'Neil, Adrian, Toth, Robert J., Browder, R. Michael, Harbin, Benjamin F. III, Holland, Cecil Ray JR., Sansom, Michael Scott, Marin, Brook
• Granted Patent: US 8,204,633 B2
• Time in Patent Office: Days
• US Class Current: 700/291
• CPC Class Codes: F24D 19/1051 for domestic hot water
• CPC Class Codes: F24H 1/0018 using electric energy supply
• CPC Class Codes: F24H 15/128 Preventing overheating
• CPC Class Codes: F24H 15/148 Assessing the current energy consumption
• CPC Class Codes: F24H 15/164 where the price of the electric supply changes with time
• CPC Class Codes: F24H 15/168 Reducing the electric power demand peak
• CPC Class Codes: F24H 15/215 before heating
• CPC Class Codes: F24H 15/219 after heating
• CPC Class Codes: F24H 15/225 at different heights of the tank
• CPC Class Codes: F24H 15/238 Flow rate
• CPC Class Codes: F24H 15/262 Weather information or forecast
• CPC Class Codes: F24H 15/269 Time, e.g. hour or date
• CPC Class Codes: F24H 15/37 of electric heaters
• CPC Class Codes: F24H 15/395 Information to users, e.g. alarms
• CPC Class Codes: F24H 15/421 using pre-stored data
• CPC Class Codes: F24H 15/464 using local wireless communication
• CPC Class Codes: F24H 9/2014 using electrical energy supply
• CPC Class Codes: F24H 9/2021 Storage heaters
• CPC Class Codes: G05B 15/02 electric
• CPC Class Codes: G05D 23/1923 using thermal energy, the cost of which varies in function of time
• CPC Class Codes: G05F 1/66 : Regulating electric power
• CPC Class Codes: H02J 3/28 : Arrangements for balancing of the load in a network by storage of energy
• CPC Class Codes: Y04S 20/222 : Demand response systems, e.g. load shedding, peak shaving

Abstract

A system for shifting energy demand from on-peak time windows to off-peak time windows by using hot water heater load shifting, while providing the end user with the level of service (i.e., availability of hot water) according to the user'"'"'s customary use described by service quality criteria. The shift is accomplished by a controller located at the end user establishment and in communication with a central control server. The controller monitors local water heater upper and/or lower temperature and controls upper and/or lower water heater heating elements in accordance with a demand shift process commanded by the central control server. The controller may determine usage and remaining capacity for reporting back to the central control server. A volumetric capacity and usage determination is disclosed. The control server may select water heaters according to use patterns and/or measured capacity. One embodiment is adapted for use with existing water heaters without disrupting safety features of the existing water heater.

Claims

1. A water heater controller for controlling a water heater to alter electrical demand while providing hot water for normal use, said water heater comprising an upper heater for heating an upper volume of water and a lower heater for heating a lower volume of water;

said water heater controller comprising;

a power control means for varying the power supplied to said upper heater and for separately varying the power supplied to said lower heater;

a processor having a memory, said memory storing a load shift algorithm comprising instructions for varying power applied by said power control, said load shift algorithm specifying a reserve volume capacity for said water heater,

a lower temperature sensor measuring a temperature of said lower volume of water and providing a resulting lower volume temperature measurement to said processor;

means for determining a remaining volume capacity of hot water in said hot water heater;

wherein said processor operates said power control device to control a temperature of said lower volume of said water heater in accordance with said load shift algorithm when said remaining capacity exceeds said reserve capacity.

2. The water heater controller of claim 1, further including a network interface, wherein said processor receives at least a part of said load shift algorithm over said network interface from a control server, said control server in communication with a plurality of water heater controllers at separate customer locations on a power grid.

3. The water heater controller of claim 2, wherein said processor provides said remaining volume capacity determination to said control server and said control server selects said water heater for load shift control in accordance with said remaining capacity of said water heater.

4. The hot water heater controller of claim 2, wherein the processor records historical usage data comprising temperature measurements and power control, and said processor provides said historical usage data to said control server over said network interface and said control server generates said load shift algorithm based on said historical usage data.

5. The hot water heater controller of claim 1, wherein the water heater includes at least one mechanical thermostat, and further including a voltage sensor sensing the voltage at an output of said at least one mechanical thermostat to determine a switch state of said at least one mechanical thermostat.

6. The hot water heater controller of claim 1, wherein the water heater controller further receives a command from said control server to override the requirement for when said remaining capacity exceeds said reserve capacity, and to lower a temperature of said water heater regardless of the remaining capacity.

7. The hot water heater controller of claim 1, wherein the water heater controller further receives a command from said control server to override the requirement for when said remaining capacity exceeds said reserve capacity, and to turn off power to the upper and lower heater regardless of the remaining capacity.

8. A method for controlling a plurality of water heaters to reduce peak loading on a power grid comprising the steps of:

receiving temperature data at a water heater control server from a plurality of water heaters connected to said power grid at separate customer locations,

generating usage pattern information for each water heater based on said temperature data;

receiving load demand information at said water heater control server from a power grid monitoring system monitoring said power grid;

said water heater control server commanding a control strategy comprising a temperature limit over time for each water heater of said plurality of water heaters based on said received temperature data, said load demand data, predicted load demand information;

wherein each water heater of said plurality of water heaters is controlled in accordance with hot water delivery quality criteria applied to said usage pattern information specific to each said water heater.

9. The method of claim 8, wherein the water heater control server commands a control procedure that includes allowing a temperature of a delivery volume of a water heater to drop to a lower temperature than normal operating temperature to delay water heater electrical demand.

10. The method of claim 8, wherein the water heater control server commands a control procedure that includes allowing a temperature of an inlet volume of a water heater to drop to a lower temperature than normal operating temperature to delay water heater electrical demand.

11. The method of claim 8, further including the step of:

receiving real time peak demand information from said power grid monitoring system;

sending a command by said water heater control server to a majority of said plurality of said water heaters to reduce demand in response to said peak demand information reported by said power grid monitoring system.

12. A method for shifting a load of a power grid comprising the steps of:

providing a control server in network communication with a plurality of water heater controllers controlling a respective plurality of water heaters;

determining historical water heater usage patterns for said plurality of water heaters;

said historical usage patterns comprising an expected usage as a function of time over at least one daily interval;

receiving a load shift goal at said control server from a power grid controller for said power grid;

selecting a first set of water heaters of said plurality of water heaters based on said historical water heater usage patterns;

receiving contemporaneous hot water remaining capacity measurements by said control server for each water heater of said first set of water heaters;

selecting a second set of water heaters based on said contemporaneous hot water remaining capacity measurements, said second set of water heaters being a subset of said first set of water heaters;

commanding said respective water heater controllers for said second set of water heaters to reduce a temperature associated with a lower heating element of each water heater of said second set of water heaters.

13. The method of claim 12, wherein the step of selecting said first set of water heaters includes selecting water heaters in accordance with at least one group, the members of said at least one group having at least one common usage category attribute.

14. The method of claim 12, wherein the remaining capacity is based on a volume measurement of hot water.

15. The method of claim 14, wherein the volume measurement is based on an upper temperature measurement proximal to an upper heating element and a lower temperature measurement proximal to a lower heating element together with power delivered to the water heater.

16. The method of claim 14, wherein the volume measurement of hot water is based on at least one temperature measurement between the top and the bottom of the water heater and a heat distribution model of the hot water heater vertical temperature profile as a function comprising usage and power applied to the water heater.

17. The method of claim 12, wherein the step of selecting by historical patterns includes selecting at least one water heater according to expected future demand.

18. The method of claim 17, wherein the expected future demand is the greatest time interval in the future.

19. The method of claim 12, wherein the usage is based on a volume measurement of hot water.

20. The method of claim 19, wherein the volume measurement is based on an upper temperature measurement proximal to an upper heating element and a lower temperature measurement proximal to a lower heating element together with power delivered to the water heater.

21. The method of claim 19, wherein the volume measurement of hot water is based on at least one temperature measurement between the top and the bottom of the water heater and a heat distribution model of the hot water heater vertical temperature profile as a function comprising usage and power applied to the water heater.

22. The method of claim 12, wherein the second set of water heaters is further selected based on maintaining a minimum available remaining capacity at each water heater of said second set of water heaters.

23. The method of claim 12, wherein an average daily usage pattern is determined as an average volumetric usage rate as a function of time over a 24 hour interval.

24. The method of claim 23, wherein the average daily pattern is determined as a moving average of a predetermined number of daily patterns determined for each day of said predetermined number of days.

25. A water heater controller for controlling a water heater to alter electrical demand, said water heater comprising an upper heater for heating an upper volume of water in accordance with an upper thermostat and a lower heater for heating a lower volume of water in accordance with a lower thermostat, said upper thermostat switching from said upper heater to said lower thermostat when said upper volume of water is above an upper thermostat set point;

said water heater controller comprising;

a power input for receiving power from a power source;

a power output for connecting to said water heater and supplying power to said water heater;

a power control device connected between said power input and said power output for varying the power supplied to said water heater;

a processor having a memory, said memory storing a load shift algorithm for varying power applied to said water heater to alter the electrical demand by said water heater, said processor controlling said water heater by controlling said power control device;

a lower temperature sensor measuring a temperature of said lower volume of water and providing a resulting lower volume temperature measurement to said processor;

a thermostat state sensor determining a switch state of said upper thermostat and communicating said switch state to said processor;

wherein said processor operates said power control device to control a temperature of said lower volume of water when said upper thermostat is switched to deliver power to said lower thermostat, said temperature of said lower volume of water controlled in accordance with said load shift algorithm, said lower volume temperature measurement, and said switch state of said upper thermostat.

26. The water heater controller of claim 25, wherein the upper thermostat state sensor comprises a voltage sensing associated with said upper thermostat.

27. The water heater controller of claim 25, wherein the water heater is a commercial item produced to be sold without said water heater controller and having a factory supplied power input terminals and said water heater controller controls said water heater through said factory supplied power input terminals.

28. The water heater controller of claim 27, wherein the water heater controller is installed to control said water heater without bypassing safety related components on said water heater.

29. The water heater controller of claim 25, further including an upper volume temperature sensor in communication with said processor for producing an upper volume temperature measurement, and said lower volume of water is further controlled in response to said upper volume temperature measurement.

30. The water heater controller of claim 29, wherein the processor uses the upper volume temperature measurement to determine whether the upper thermostat is switched to the lower thermostat when the power controller is switched off.