Automatic set point detection for water heaters operating in a demand response

Patent metadata

Field	Value
Publication number	US-2016178239-A1
Application number	US-201514976878-A
Country	US
Kind code	A1
Filing date	Dec 21, 2015
Priority date	Dec 22, 2014
Publication date	Jun 23, 2016
Grant date	—

Abstract

An electric water heater that includes a thermostat is retrofitted for remote control as follows. A relay is installed on an electrical feed to the electric water heater. Water temperature and electric current or power through the electrical feed are measured over time with the relay closed, and the thermostat deadband maximum and minimum are detected as the water temperature at which the thermostat turns the heating element off, and the water temperature at which the thermostat turns the heating element on, respectively. The detected thermostat deadband maximum and minimum are stored as load controller deadband maximum and minimum, respectively. The thermostat set point is raised, and the electric water heater is thereafter controlled using the load controller by operations including closing the relay when the water temperature falls below the load controller deadband minimum and opening the relay when the water temperature rises above the load controller deadband maximum.

First claim

1 . An electric water heater control system for controlling a water heater having a heating element and a thermostat, the electric water heater control system comprising:
a power regulation device configured to regulate electrical power to the heating element of the water heater; and a load controller operatively coupled to operate the power regulation device, the load controller comprising an electronic data processing device, non-transitory storage storing at least load controller deadband limits, and a communication link, the load controller programmed to perform a thermostat algorithm to operate the power regulation device to regulate water temperature in the electric water heater respective to the stored load controller deadband limits.

2 . The electric water heater control system of claim 1 wherein the load controller is further programmed to perform a load controller setup algorithm including:
performing a thermostat deadband measurement algorithm to detect the thermostat deadband limits; and
setting the stored load controller deadband limits based on the detected thermostat deadband limits.

3 . The electric water heater control system of claim 2 wherein the thermostat deadband measurement algorithm includes:
performing a monitoring operation including measuring water temperature and monitoring electric current or power to the heating element over time with the power regulation device applying power to the heating element of the electric water heater;
during the monitoring operation, detecting the thermostat deadband maximum as the water temperature at which the thermostat turns the heating element off; and
during the monitoring operation, detecting the thermostat deadband minimum as the water temperature at which the thermostat turns the heating element on.

4 . The electric water heater control system of claim 3 wherein:
the thermostat deadband measurement algorithm further includes, during the monitoring operation, detecting the highest water temperature measured after the thermostat turns the heating element off; and
the load controller setup algorithm further includes storing a raised thermostat deadband maximum in the non-transitory storage of the load controller wherein the raised thermostat deadband maximum is greater than the highest water temperature measured after the thermostat turns the heating element off.

5 . The electric water heater control system of claim 4 wherein the load controller is further programmed to perform a thermostat adjustment detection algorithm after performing the load controller setup algorithm, the thermostat adjustment detection algorithm including:
measuring water temperature and monitoring heating element current or power over time with the power regulation device applying power to the heating element of the electric water heater and detecting a current thermostat deadband maximum as the water temperature at which the thermostat turns the heating element off;
determining a thermostat set point change as equal to a difference between the current thermostat deadband maximum and the raised thermostat deadband maximum stored in the non-transitory storage of the load controller;
after the determining, updating the raised thermostat deadband maximum stored in the non-transitory storage of the load controller to equal the current thermostat deadband maximum; and
adjusting the stored load controller deadband limits based on the determined thermostat set point change.

6 . The electric water heater control system of claim 2 wherein setting the stored load controller deadband limits based on the detected thermostat deadband limits includes:
setting the stored load controller deadband maximum equal to the detected thermostat deadband maximum; and
setting the stored load controller deadband minimum equal to the detected thermostat deadband minimum.

7 . The electric water heater control system of claim 1 wherein the load controller is further programmed to perform a thermostat deadband maximum detection algorithm including:
performing a monitoring operation including measuring water temperature and monitoring heating element current or power over time with the power regulation device applying power to the heating element of the electric water heater; and
during the monitoring operation, detecting the thermostat deadband maximum as the water temperature at which the thermostat turns the heating element off.

8 . The electric water heater control system of claim 7 wherein the load controller is further programmed to store the detected thermostat deadband maximum in the non-transitory storage of the load controller and to perform a thermostat adjustment detection algorithm including:
repeating the thermostat deadband maximum detection algorithm to generate a current thermostat deadband maximum;
determining a thermostat set point change as equal to a difference between the current thermostat deadband maximum and the thermostat deadband maximum stored in the non-transitory storage of the load controller;
after the determining, updating the thermostat deadband maximum stored in the non-transitory storage of the load controller to equal the current thermostat deadband maximum; and
adjusting the stored load controller deadband limits based on the determined thermostat set point change.

9 . The electric water heater control system of claim 1 wherein the power regulation device comprises a power relay.

10 . The electric water heater control system of claim 1 wherein the load controller is further programmed to perform a demand response algorithm in response to a demand response instruction received via the communication link of the load controller to increase or decrease energy consumption by the electric water heater.

11 . The electric water heater control system of claim 10 wherein the demand response algorithm includes at least one of:
(1) operating the power regulation device to reduce or turn off power to the heating element of the electric water heater in response to a demand response instruction comprising a curtailment instruction, and
(2) operating the power regulation device to increase or decrease energy consumption by the electric water heater in response to a demand response instruction comprising an automatic generation control (AGC) signal.

12 . An apparatus comprising:
an electric water heater including a heating element and a thermostat having a raised thermostat deadband maximum; a power regulation device configured to regulate power to the heating element of the electric water heater; and a load controller operatively coupled to operate the power regulation device, the load controller comprising an electronic data processing device and non-transitory storage storing at least load controller deadband limits and the raised thermostat deadband maximum which is raised as compared with the load controller deadband maximum; wherein the load controller is configured to perform a thermostat algorithm to operate the power regulation device to regulate water temperature in the electric water heater respective to the load controller deadband limits without the regulated water temperature reaching the raised thermostat deadband maximum.

13 . The apparatus of claim 12 wherein the load controller is further configured to perform a load controller setup algorithm including:
performing a thermostat deadband measurement algorithm to detect the thermostat deadband limits of the thermostat of the electric water heater; and
setting the stored load controller deadband limits equal to the detected thermostat deadband limits.

14 . The apparatus of claim 13 whe

Assignees

• Battelle Memorial Institute

Inventors

• Thornton Douglas
• Black Jason W
• Adams Lauren

Classifications

• G05B13/0265

  the criterion being a learning criterion · CPC title

• G05F1/66

  Regulating electric power · CPC title

• G05D23/20

  with sensing elements having variation of electric or magnetic properties with change of temperature (G05D23/13 takes precedence) · CPC title

• G06N3/126

  Evolutionary algorithms, e.g. genetic algorithms or genetic programming · CPC title

• G05D23/1905

  associated with tele control · CPC title