A Computationally Inexpensive Energy Model for Horizontal Electric Water Heaters With Scheduling

Abstract

Electric water heaters (EWHs) remain one of the main contributors to energy consumption in countries where they are used. EWH models serve as a step towards achieving optimised control, and can also be used to inform users of expected savings due to changes, if the model is energy-based. Various models have been proposed, but none of them include more than half of the six key features that the model presented in this paper supports: horizontal orientation; schedule control; low computational complexity; validation of the model; multinodal stratification; and multinodal standing losses. The presented model is validated against six datasets: four comprising 900 hours with multiple water usage events; and two with only standing losses. The results show that the model estimates energy consumption over ten days including usage with an error of less than 2% and 5% for schedule control and thermostat control respectively. The simulation model is simple enough to execute ten days of simulation in less than 100 milliseconds on a standard desktop machine, 150 times faster than a prominent model from literature, making it also suitable for large scale simulations or for use on mobile devices.

Collaborative control of thermostatically controlled appliances for balancing renewable generation in smart grid

“…In this system, the user settings for each EWH are shown in Table I. The physical attributes and the initial status for each EWH are given in Table II [13,21,26]. Suppose the residents do not use hot water during this period.…”

A centralized demand response control strategy for domestic electric water heater group based on appliance cloud platform

“…According to Ref. , the energy flow of a EWH is analyzed in static mode of operation, as shown in Fig. .…”

Multi-objective optimization for electric water heater using mixed integer linear programming

“…Many EWH models and control strategies have been proposed for optimizing and controlling the energy usage of the EWH [15][16][17][18]. The performance of several different control strategies of an EWH under dynamic prices is analyzed in [15].…”

“…Reference [16] proposes a system for the realtime control of EWHs with wireless communications and machine-to-machine networking. A two-node EWH model, proposed in [17], can realize the control of an EWH in a computationally inexpensive and accurate way. Reference [18] introduces a systematic way to formulate an optimal load scheduling model of an EWH considering temperature constraints.…”

“…And in the second process, when the heated water leaves the tank through the outlet pipe, it still needs to be fixed with cold water by the thermostaticallycontrolled automatic water mixer (TCAWM), so that the tap water temperature can keep constant. Many works [13,17,18] consider the cold-water mixing of the first process, but neglect the second one.…”