Centrally Adapted Optimal Control of Multiple Electric Water Heaters

Ritchie, M.J.; Engelbrecht, J.A.A.; Booysen, M.J.

doi:10.3390/en15041521

Cited by 5 publications

(2 citation statements)

References 41 publications

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“…Successful studies into EWH smart controls include a centrally adapted control model which avoided the peak power by scheduling each EWH, thereby reducing the peak load of 1.05 kW/EWH to 0.4 kW/EWH [17] and a deep Q-networks algorithm for water heaters under T.O.U pricing that showed electricity cost savings up to 35% [18]. Other recent examples of EWH controls to reduce grid impact from electric vehicles (EV) show that thermal energy storage is viable to improve grid operation, given the smart technology to control them is in place [19,20].…”

Section: Technology Reviewmentioning

confidence: 99%

Electric Water Heater Modeling for Large-Scale Distribution Power Systems Studies with Energy Storage CTA-2045 Based VPP and CVR

Alden

Gong²,

Rooney³

et al. 2023

Energies

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As the smart grid involves more new technologies such as electric vehicles (EVs) and distributed energy resources (DERs), more attention is needed in research to general energy storage (GES) based energy management systems (EMS) that account for all possible load shifting and control strategies, specifically with major appliances that are projected to continue electrification such as the electric water heater (EWH). In this work, a methodology for a modified single-node model of a resistive EWH is proposed with improved internal tank temperature for user comfort modeling and capabilities for conservation voltage reduction (CVR) simulations as well as Energy Star and Consumer Technology Association communications protocol (CTA-2045) compliant controls, including energy storage calculations for “energy take”. Daily and weekly simulations are performed on a representative IEEE test feeder distribution system with experimental load and hot water draw (HWD) profiles to consider user comfort. Sequential controls are developed to reduce power spikes from controls and lead to peak shavings. It is found that EWHs are suitable for virtual power plant (VPP) operation with sustainable tank temperatures, i.e., average water temperature is maintained at set-point or above at the end of the control period while shifting up to 78% of EWH energy out of shed windows per day and 75% over a week, which amounts to up to 23% of the total load shifted on the example power system. While CVR simulations reduced the peak power of individual EWHs, the aggregation effect at the distribution level negates this reduction in power for the community. The EWH is shown as an energy constant load without consistent benefit from CVR across the example community with low energy reductions of less than 0.1% and, in some cases, increased daily energy by 0.18%.

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Section: Technology Reviewmentioning

confidence: 99%

Electric Water Heater Modeling for Large-Scale Distribution Power Systems Studies with Energy Storage CTA-2045 Based VPP and CVR

Alden

Gong²,

Rooney³

et al. 2023

Energies

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“…In addition, the comfort, peak-load and energy usage, as discussed in Roux et al [3] also need to be considered. The troika of challenges visualised by Ritchie et al [23] could therefore be extended to incorporate the optimisation of energy with the consideration of microbial growth mitigation.…”

Section: Health Considerationsmentioning

confidence: 99%

Thermal Stratification and Temperature Variation in Horizontal Electric Water Heaters: A Characterisation Platform

2022

Self Cite

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Electric water heaters, which have the capacity to act as thermal energy storage, are well suited to demand management strategies in smart grid applications. However, finding the balance between managing power load, reducing thermal energy losses, user’s convenience, and bacterial growth control, requires accurate modelling of the internal thermal dynamics of the tank, including stratification. As a black box, this unknown is dependent on a multitude of environmental factors (e.g., ambient temperature and inlet temperature), water draw patterns, scheduling, set temperatures and orientation of the vessel. The latter affects the stratification and temperature variation inside the tank, and therefore has a direct bearing on the balancing act of demand management. Although this has been assessed inside vertically oriented tanks, what happens inside the horizontal variety—ubiquitous in developing countries—is currently left to the guesswork. In this paper, we present the development of an embedded hardware and software platform with which the temperature variations inside a horizontal water heater can be characterised under numerous environmental and usage conditions. The importance of doing so is highlighted by the preliminary results, which clearly show the expected substantial temperature variation along the vertical axis, but also show interesting phenomena along the longitudinal and transverse axes, for both static (no water draw) and dynamic (with water draw) conditions. We conclude by highlighting potential for further research.

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Loadshedding-induced transients due to battery backup systems and electric water heaters

Ritchie,

Engelbrecht,

Booysen

2024

Applied Energy

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Centrally Adapted Optimal Control of Multiple Electric Water Heaters

Cited by 5 publications

References 41 publications

Electric Water Heater Modeling for Large-Scale Distribution Power Systems Studies with Energy Storage CTA-2045 Based VPP and CVR

Electric Water Heater Modeling for Large-Scale Distribution Power Systems Studies with Energy Storage CTA-2045 Based VPP and CVR

Thermal Stratification and Temperature Variation in Horizontal Electric Water Heaters: A Characterisation Platform

Loadshedding-induced transients due to battery backup systems and electric water heaters

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