Remote leak and failure detection of electrical water heaters through temperature and power monitoring

1. A demand response system comprising:

an aggregation of electric water heaters, each electric water heater including an electronic controller;

an aggregator in operative communication with the electric water heaters via the electronic controllers to receive thermostat readings and power consumption readings from the electric water heaters and to communicate demand response dispatch signals to the electric water heaters, the aggregator comprising an electronic data processing device performs operations including:

responding to instructions for a desired demand response by generating the demand response dispatch signals for the electric water heaters and in response causes the aggregation to draw electrical power of the desired demand response, and

determining whether an electric water heater of the aggregation has a failure and generating a notification of the failure, wherein the electric water heater includes an upper heating element with an upper thermostat and a lower heating element with a lower thermostat, the determining including:

determining whether the electric water heater has a failed heating element based on the thermostat readings received from the electric water heater, and

determining whether the lower heating element of the electric water heater has failed based on a difference between the upper thermostat reading and the lower thermostat reading.

2. The demand response system of claim 1 wherein the determining whether the electric water heater has a failed heating element comprises:

determining that the lower heating element of the electric water heater has failed based at least on whether a difference between the upper thermostat reading and the lower thermostat reading exceeds a threshold.

3. The demand response system of claim 1 wherein the determining whether the electric water heater has a failed heating element comprises:

determining whether the upper heating element of the electric water heater has failed based on a change of the upper thermostat reading over a predefined time interval.

4. The demand response system of claim 1 the determining whether the electric water heater has a failed heating element comprises:

determining that the upper heating element of the electric water heater has failed if a change of the upper thermostat reading over a predefined time interval exceeds a threshold.

5. The demand response system of claim 1 wherein responding to instructions for the desired demand response by generating the demand response dispatch signals for the electric water heaters causes the aggregation to draw electrical power of the desired demand response comprises:

receiving the desired demand response comprising an automatic generation control (AGC) signal; and

generating the demand response dispatch signals for the electric water heaters based on the AGC signal causes the aggregation to draw electrical power by frequency regulation.

6. The demand response system of claim 1 wherein responding to instructions for the desired demand response by generating the demand response dispatch signals for the electric water heaters causes the aggregation to draw electrical power of the desired demand response comprises:

determining constraints on operation of the electric water heaters; and

applying a dispatch algorithm to perform a constrained optimization of the demand response dispatch signals for a next time interval in order to optimally satisfy the desired demand response while obeying the constraints on operation of the electric water heaters.

7. A demand response method operating on an aggregation of electric water heaters wherein each electric water heater includes an electronic controller, the demand response method comprising:

at an aggregator comprising an electronic data processing device, receiving thermostat and power consumption readings from the electric water heaters via the electronic controllers of the electric water heaters;

at the aggregator, receiving instructions for a desired demand response;

using the aggregator comprising the electronic data processing device, generating demand response dispatch signals for the electric water heaters and in response causing the aggregation to draw electrical power of the desired demand response;

communicating the demand response dispatch signals to the electric water heaters and operating the electric water heaters in accordance with the demand response dispatch signals; and

using the aggregator comprising the electronic data processing device, determining an electric water heater of the aggregation has a failure and generating a notification of the failure, wherein the electric water heater includes an upper heating element with an upper thermostat and a lower heating element with a lower thermostat, the determining including:

determining the electric water heater has a failed heating element based on the thermostat readings received at the aggregator from the electric water heater, and

determining whether the lower heating element of the electric water heater has failed based on a difference between the upper thermostat reading and the lower thermostat reading.

8. The demand response method of claim 7 wherein determining the electric water heater has a failed heating element comprises:

determining whether the upper heating element of the electric water heater has failed based on a change of the upper thermostat reading over a predefined time interval.

9. The demand response method of claim 7 wherein:

receiving instructions for the desired demand response comprises receiving an automatic generation control (AGC) signal of an electric power grid supplying electricity to the aggregation; and

generating demand response dispatch signals for the electric water heaters comprises generating the demand response dispatch signals based on the AGC signal causes the aggregation to draw electrical power by frequency regulation.

10. The demand response method of claim 7 wherein generating the demand response dispatch signals for the electric water heaters comprises:

determining constraints on operation of the electric water heaters; and

applying a dispatch algorithm to perform a constrained optimization of the demand response dispatch signals for a next time interval in order to optimally satisfy the desired demand response while obeying the constraints on operation of the electric water heaters.

11. The demand response method of claim 7 , wherein the determining whether the electric water heater has a failed heating element comprises:

determining that the lower heating element of the electric water heater has failed based at least on whether a difference between the upper thermostat reading and the lower thermostat reading exceeds a threshold.

12. The demand response method of claim 7 , wherein the determining whether the electric water heater has a failed heating element comprises:

determining that the upper heating element of the electric water heater has failed if a change of the upper thermostat reading over a predefined time interval exceeds a threshold.