Electronic Load Disconnect Control for HVAC Peak Demand Spreading
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Solution Overview
Problem
During peak electricity demand periods, especially in summer months when air conditioning usage increases, power demand often exceeds availability, leading to disruptive 'brownout' or rolling blackout conditions.
Innovation Solution
An electronic circuit board is introduced to intercept and override thermostat controls for air conditioning units and water heaters, implementing a load spreading algorithm to minimize simultaneous operation and reduce peak power demand by strategically turning units on and off.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If multiple air conditioning units and water heaters operate independently based on their own thermostat controls during peak demand periods, then each unit can maintain its set temperature, but the simultaneous operation of multiple units causes peak power demand to exceed availability, resulting in brownout or rolling blackout conditions
Solution Approach 1:
The patent combines multiple independent thermostat controls into a single centralized controller that manages all air conditioning units and water heaters. This unified control system coordinates the operation of multiple units to prevent simultaneous startup, thereby reducing peak power demand while maintaining temperature setpoints across all controlled devices.
Solution Approach 2:
The controller implements preliminary sequencing by predicting and preventing simultaneous operation of multiple units before peak demand occurs. When the controller anticipates that multiple units would otherwise start simultaneously based on their individual thermostats, it proactively sequences their startup to stagger the load, avoiding brownout conditions.
2Power
If a centralized controller coordinates multiple HVAC units to reduce peak demand, then simultaneous operation is minimized and brownout conditions are reduced, but the system requires an electronic circuit board to intercept and override thermostat controls
Solution Approach 1:
The patent introduces an electronic circuit board as an intermediary device that is installed between existing thermostats and HVAC units. This circuit board intercepts control signals from individual thermostats and overrides them with coordinated control commands from the centralized controller, enabling load management without requiring complete system replacement or complex rewiring.
Solution Approach 2:
The control system is segmented into independent functional modules: individual thermostat interfaces, the electronic circuit board with centralized controller, and multiple HVAC unit outputs. This modular architecture allows the system to be installed by simply interposing the circuit board in existing wiring, avoiding labor-intensive rewiring while maintaining individual thermostat functionality for each zone.
3Power
If the electronic circuit board overrides thermostat settings to implement load spreading, then peak power demand is reduced, but individual thermostat preferences and settings are disregarded
Solution Approach 1:
The controller dynamically adjusts the level of override based on real-time conditions. During normal operation, individual thermostat preferences are respected. However, when the controller detects conditions that would lead to peak demand or brownout, it dynamically overrides thermostat settings to sequence unit operation, thereby balancing user comfort with grid stability.
Data Source
AI summary
Electrical load spreading arrangements reduce peak power demand. An enclosure houses an electronic circuit board, which receives at a first input terminal a first thermostat control signal from a thermostat intended to control a first air conditioning unit and at a second input terminal a second thermostat control signal from a thermostat intended to control a second AC unit. A controller on the circuit board is programmed with instructions stored in a memory coupled to the controller causing the controller to monitor the first and second input terminals to determine the timing and duration of the thermostat control signals passed to the output terminals for activating or deactivating the AC units such that overlapping operation of the AC units is reduced particularly during peak demand periods. A similar arrangement may be applied to a broader class of HVAC equipment, including water heaters, for example.