Water Heater Load Shed Control Using Thermostat Signal Detection
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Solution Overview
Problem
Electric utilities face challenges in managing peak demand during hot or cold weather, as traditional methods like load shedding can inconvenience customers and may not effectively detect low hot water reserves in electric water heaters, leading to unnecessary termination of load control events and potential power generation capacity issues.
Innovation Solution
A method and circuit for detecting low hot water reserves in electric water heaters using a voltage signal level detection circuit to monitor the switching state of the thermostat control module, allowing for decoupling and recoupling of power to the heating element, thereby terminating or pausing load-shedding events to replenish hot water reserves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Difficulty of detecting and measuring
If temperature probes/sensors are installed on the water heater to detect low hot water reserve, then detection capability is improved, but device complexity increases and installation difficulty increases
Solution Approach 1:
The patent uses the existing thermostat control module as an intermediary to detect low hot water reserve conditions. Instead of installing new sensors, the system monitors signals already present in the thermostat control module, which naturally responds to water temperature and reserve levels. This intermediary approach enables detection capability while avoiding the complexity of additional sensing devices.
Solution Approach 2:
The existing thermostat control module on the water heater is leveraged to perform the detection function. The module already contains the necessary sensing and control capabilities to detect low hot water conditions, so no external detection devices are needed. The system essentially uses its own built-in control module to serve the dual purpose of temperature control and reserve level detection.
2Difficulty of detecting and measuring
If temperature probes/sensors are installed on the water heater, then detection capability is improved, but ease of operation deteriorates due to complex installation requirements
Solution Approach 1:
The patent utilizes the existing thermostat control module as an intermediary that already has access to the necessary operational signals. This eliminates the need for separate probe installation, wiring, and calibration steps that would complicate the operation and installation process.
Solution Approach 2:
The detection function is extracted from the concept of physical probe installation and implemented through signal monitoring of the existing control module. This extraction removes the physical installation complexity while retaining the detection capability, as the control module's existing signals already indicate hot water reserve status.
3Loss of energy
If load control devices interrupt power to water heaters during peak load times, then power demand is reduced, but customer convenience deteriorates when hot water reserve is insufficient
Solution Approach 1:
The system implements feedback by continuously monitoring the thermostat control module's signals to detect low hot water reserve conditions. When insufficient hot water is detected, the system provides feedback to the load control device to prevent or terminate power interruption, thereby maintaining customer convenience while still achieving power demand reduction when adequate reserves exist.
Solution Approach 2:
The system performs preliminary detection of low hot water reserve conditions before the load control device interrupts power. By detecting the insufficient reserve status in advance, the system can prevent the inconvenient power interruption from occurring, allowing the water heater to maintain operation and ensure adequate hot water supply during peak periods.
4Power
If electric utilities build new power plants to meet peak demand, then power supply capacity is improved, but cost increases significantly
Solution Approach 1:
The system performs preliminary detection and prevention of hot water depletion before peak demand occurs. By ensuring adequate hot water reserves are maintained through early detection and load control adjustments, the system prevents the need for additional power generation capacity during peak periods, avoiding the high cost of building new power plants.
Solution Approach 2:
The feedback mechanism monitors hot water reserve levels and adjusts power delivery accordingly. This real-time feedback allows the system to optimize power usage, maintaining adequate hot water supply during peak demand without requiring excessive power generation capacity, thereby avoiding the high costs associated with building new power plants.
Data Source
AI summary
A method of operating a water heater in a load shed mode can include detecting that an upper water heater thermostat control module in a water heater is calling for heat to be provided via an upper heating element of the water heater while the water heater is in a load shed mode of operation wherein a first leg of power to the water heater is decoupled from an input to the upper water heater thermostat control module and responsive to the upper water heater thermostat control module calling for heat, transmitting a signal to end the load shed mode of operation at the water heater so that the first leg of power to the water heater is coupled to the input of the upper water heater thermostat control module so that the upper heating element of the water heater is enabled to heat water responsive to the upper water heater thermostat control module calling for heat.