Self-tuning charge control scheme for domestic stored-energy heating systems

The paper examines the problem of controlling domestic electric stored-energy heating systems and describes the development of a self-tuning control scheme which can adjust the off-peak charging of the store to minimise electrical energy consumption. The charging time is controlled by a store temperature-regulator which is designed by application of the well known self-tuning minimum-variance control technique. The regulator uses a statistical estimator, based on a lumped-parameter model of the thermal behaviour of the building and heating system, to predict the next day´s heating energy demand before the start of the off-peak charging period. The control scheme assumes no prior knowledge of the thermal characteristics of the building or heating plant and is suitable for low-cost microprocessor implementation. The long-term performance of the self-tuning charge controller is assessed by digital simulation of a building heated by one of two widely different types of commercial storage heating systems (a fan-assisted block storage heater and a water-storage central heating system). Results are presented which show that the control scheme behaves well and achieves substantial energy savings without the need for manual commissioning. Modification of the basic self-tuning control scheme to compensate for the peculiarities observed in the operation of high-leakage or low-capacity stores is also investigated.