Dynamic Coupling Analysis and Control of an Integrated Thermal Energy Storage System

Thermal energy storage (TES) is commonly used in district heating systems (DHSs) to collect and store thermal energy for a later use which, in turn, may improve the efficiency and performance of the DHS. Thus, the TES' charging and discharging processes are fundamental. The increasing diversity of heating technologies allows to store energy from different sources into a single storage element at the same time; this increases the system's complexity and induces dynamic coupling between the heat flow inputs and the internal temperature distribution of the storage element. This paper studies such dynamic coupling and assesses its effect on the charging and discharging control process of an integrated TES system for DHSs. Using linear control theory tools, the effect of a secondary energy source on the main system's control loop is assessed, providing an insight on the system dynamics which, in turn, is helpful to determine suitable feedback control configurations.