A Novel Domestic Electric Water Heater Control Method

As one of important thermostatically controlled loads (TCLs), domestic electric water heaters (DEWHs) show considerable potential for utilities to shave peak load working with direct load control (DLC). The electricity consumption of DEWHs is high in regard to daily domestic electricity consumption, which shows the potential for peak shifting services through the direct control of DEWHs. In practice, off-control is commonly used to control DEWHs, and finding suitable DEWHs to turn off is the main objective of DLC. However, it is difficult to decide which DEWH can be turned off when end-user comfort is taken into consideration, especially with the absence of temperature measurement information. In this paper, a novel control method is proposed to control DEWHs without temperature information. A time-varied weight matrix is generated based on patterns of DEWHs, and the temperatures of DEWHs can be estimated by the weight matrix and their states. The weight matrix and heating durations are used to generate a customer satisfaction prediction index, which can be used as a reference during DLC. The index can be used to select suitable DEWHs to turn off or to turn back on to maintain end-user comfort. The proposed method only needs the on-off states of DEWHs, which are available in practice. Simulation results prove that the proposed method can work well to reduce peak demand without affecting end-user comfort.