Abstract
Breakthroughs in smart grid technology make it possible to deliver electricity in controlled and intelligent ways to improve energy efficiency between the user and the utility. Demand-side management strategies can reduce overall energy usage and shift consumption to reduce peak loads. Electric water heaters account for 40% of residential energy consumption. Since they are thermal storage devices, advanced control strategies can improve their efficiency. However, existing methods disregard the connection between the user and the grid. We propose a centrally adapted control model that allows for coordinated scheduling to adapt the optimal control schedule of each EWH, spreading the load into off-peak periods to ensure that the grid’s generation capacity is not exceeded. We consider two strategies for the delivery of hot water: temperature matching, and energy matching with Legionella sterilisation, and compare them to a baseline strategy where the thermostat is always switched on. Simulation results for a grid of 77 EWHs showed that an unconstrained peak load of 1.05 kW/EWH can be reduced as low as 0.4 kW/EWH and achieve a median energy saving per EWH of 0.38 kWh/day for the temperature matching strategy and 0.64 kWh/day for the energy matching strategy, without reducing the user’s comfort.
Highlights
The prevailing view of electricity generation is that the system will be most efficient when fluctuations are mitigated as much as possible
The system presented in this study aims to minimise three factors: the overall electrical energy used by an individual electric water heaters (EWHs), the number of times the user experiences cold water temperatures, and the peak loads on the grid as a result of supplying electricity to many
Thermostat control (TC): The EWH temperature is always maintained at the set-point temperature
Summary
The prevailing view of electricity generation is that the system will be most efficient when fluctuations are mitigated as much as possible. Techniques have been devised to smooth the demand profile of the grid and limit the power demand [1,2,3,4]. This is important in the case of electric water heaters (EWHs), as they account for 40% of the residential sector’s energy consumption, and this sector accounts for 20% of greenhouse gas emissions [5,6,7,8,9,10]. South Africa currently lacks the generation capacity to meet the demand on the grid This has led to frequent power outages, necessitating load-shedding [11]. The energy required to operate the five million water heaters in the country is responsible for 30% to
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