Parameter estimation of electric water heater models using extended Kalman filter

Electric water heaters have been regarded as a load to be exploited in residential energy management applications due to their potential energy storage capacity. Nevertheless, the implementation of control strategies for water heater systems requires high-performance models which must be capable of reproducing a water heater's internal operation dynamics, especially their inner water temperature variations. Therefore, appropriate water heater model selection and design is a challenge. This paper presents physical parameter estimation methods for two typical water heater models based on experimental data. The first method is based on the evaluation of the on-off times of the heating elements when there is no water consumption; the second method uses an extended Kalman filter to estimate the model's states and physical parameters. Additionally, by leveraging these estimated parameters, a comparative study of the temperature estimation and electric power consumption in both water heater models has been produced and is included. Experimental results show that a precise estimation of the physical parameters in the model allows the water thermal process to accurately identify and predict future power and energy consumption values.