Parameter identification of thermal models for domestic electric water heaters in a direct load control program

This paper investigates an approach for identification of physical models of domestic electric water heaters (DEWH´s) that are used to provide aggregated regulation services. The model is used within a direct load control (DLC) algorithm to estimate and forecast the water usage and temperature of individual water heaters. Individual physical models are used instead of aggregated models to allow the DLC algorithm to minimize the impact on customers by customizing the control of each water heater to individual water usage patterns. A single-zone lumped-parameter thermal model was considered for a single element DEWH. Two scenarios are investigated: i) when measurements of water temperature and heater power consumption are available, and ii) when measurements of only heater power consumption are available. The problem is challenging because water usage patterns cannot be measured directly and are governed by the behaviour of individual customers.