A New DH Control Algorithm for a Combined Supply and Feed-In Substation and Testing Through Hardware-In-The-Loop

The integration of decentralized feed-in of solar heat into district heating networks results in a high volatility regarding daily and seasonal pressure and temperature characteristics. Therefore new control and automation devices and algorithms are required to handle the complexity of the system. Furthermore the presented combined supply and feed-in substation - a so-called prosumer substation - needs a state machine (automation of switching between the several operation modes) in order to optimise the distribution of solar heat gains: feed-in into the district heating network and/or partly to local consumption. This paper presents results regarding the developed controller system, the test rig for emulation of the solar thermal system and a building as well as measurement data of a complex part of chosen daily load curves. The latter is the synthesis of the emulation test rig, the functional model of the combined supply and feed-in substation and the control system. The presented results are gained as parts of the R&D projects “Dezentrale Einspeisung in Nah- und Fernwärmesysteme unter besonderer Berücksichtigung der Solarthermie” and “Kostenreduktionspotential beim Ausbau der Solarisierung von Fernwärmenetzen durch Standardisierung” (see [1] and [2],[3]).