Water Heater Control for Absorbing Excess Distributed Generation
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Solution Overview
Problem
Conventional power grids struggle to handle excess power from distributed generation sources, leading to upstream current flow, overvoltage, and disconnection issues, which limits the implementation of renewable technologies due to their inability to maintain a clean sinusoidal power supply.
Innovation Solution
A water heater system with upper and lower heating packages and a controller that absorbs excess power as thermal energy by adjusting heating based on voltage and temperature conditions, preventing disconnection and maintaining grid stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If DG sources are implemented to reduce greenhouse gas emissions, then renewable energy usage increases, but upstream current flow and overvoltage damage the power grid
Solution Approach 1:
The patent converts the harmful effect of excess DG power (which causes upstream current flow and overvoltage) into a beneficial thermal energy storage in the water heater. The water heater absorbs the excess electrical energy and transforms it into thermal energy, preventing grid damage while utilizing the renewable energy that would otherwise be wasted.
Solution Approach 2:
The water heater acts as an intermediary device between the DG sources and the power grid. It mediates the power flow by absorbing excess energy during high DG generation periods and can potentially release it during peak demand periods, thus stabilizing the grid while enabling higher DG penetration.
2Loss of energy
If DG sources are implemented to reduce power plant load, then greenhouse gas emissions decrease, but the power grid disconnects DG sources when power exceeds demand
Solution Approach 1:
The water heater converts the harmful disconnection scenario into a benefit by providing a local energy sink. When DG power exceeds local demand, instead of disconnecting the DG sources, the excess power is directed to heat water, thereby utilizing the renewable energy that would otherwise be curtailed and preventing greenhouse gas emissions.
Solution Approach 2:
The system changes the operational parameters of the water heater based on grid conditions. When voltage indicates excess DG power (higher than normal), the water heater increases its power consumption to absorb the surplus energy, thereby maintaining DG source connection and maximizing renewable energy utilization.
3Device complexity
If conventional power grids maintain predetermined frequency, then power distribution is simple, but DG sources degrading signal shape limit renewable technology implementation
Solution Approach 1:
The water heater converts the harmful effect of DG sources degrading the power signal into a benefit by providing a resistive load that does not contribute to signal degradation. The heating element presents a purely resistive impedance that draws current in phase with voltage, thereby not introducing harmonics or distorting the sinusoidal waveform, while still consuming the excess DG power.
4Reliability
If water heater absorbs excess power as thermal energy, then grid stability is maintained, but additional control complexity is required
Solution Approach 1:
The water heater control system uses voltage magnitude as a feedback signal to determine when excess DG power is available. When the voltage exceeds a predetermined threshold, indicating surplus power from DG sources, the controller activates the heating element to absorb the excess energy. This simple feedback mechanism enables the water heater to respond automatically to grid conditions without complex communication infrastructure.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The system effectively absorbs and stores excess renewable energy, preventing grid disconnection and equipment damage, while ensuring a stable power supply, thus enabling efficient use of renewable energy sources.
Implementation Method 1
The upper heating package includes an upper thermostat configured to sense an upper portion temperature and an upper resistive heating element configured to heat the upper portion. Likewise, the lower heating package includes a lower thermostat configured to sense a lower portion temperature, and a lower resistive heating element configured to heat the lower portion.
Implementation Method 2
The upper heating package includes an upper thermostat configured to sense an upper portion temperature and an upper resistive heating element configured to heat the upper portion. Likewise, the lower heating package includes a lower thermostat configured to sense a lower portion temperature
Data Source
AI summary
Systems and methods for storing power from distributed generation systems or other loads and sources that affect line voltage are disclosed. In embodiments, a water heater can be powered in a way that absorbs excess power from the grid by heating water when a controller senses excess power generation in the grid. Excess power generation can be sensed by either an increase in line voltage amplitude above a predetermined standard, or an increase in line voltage frequency above a predetermined standard.