Optimized control strategies for solar district heating systems

Solar district heating (SDH) systems are a proven concept for the supply of space heating and/or domestic hot water using solar energy as the main heat source. SDH systems with a high solar fraction include seasonal thermal storage and various subsystems with different time scales that must be managed by the supervisory control system. This paper presents the development of optimized control strategies for the Drake Landing Solar Community in Okotoks (Alberta, Canada). The proposed strategies, based on the application of model predictive control concepts, aim to further reduce the use of auxiliary energy for heating (gas) while also reducing the pumping energy (electricity). Perfect forecasts for the weather and the SDH loads are assumed in the study and a detailed TRNSYS model is used. Results show that the primary energy consumption can be reduced by 5% by updating the supervisory control strategies.