CASE: OPTIMAL OPERATION OF A PLANNED CITY DISTRICT
This case represents a planned city district that consists of one producer and 16 consumers. We integrated physically relevant constraints (temperatures, mass flows and pressures) based on physical and operational limitations in the optimization formulation. Figure 6 shows that the heat loss and transport delay are correctly represented in the optimization model: the customer at the network periphery received a slightly colder water and with a certain delay. During high load, the distribution pump of the producer is at its maximum capacity and the mass rate saturates (Figure 7). As a consequence, the supply temperature is increased to fulfill the heat demand of all customers. The temperature increase is done in advance to compensate for the mass flow dependent delays in the network. The solution time is sufficiently low for a real-time application. MODELS WORK FOR DISTRICT HEATING The results show that the framework is well- suited for simulating larger scale 4GDH systems and that the solution time of the continuous optimization problem is sufficiently low for real-time applications. Current methods and
Figure 6: The optimization model presents heat loss and transport delay correctly.
Figure 7: During high load, the distribution pump of the producer is at its maximum capacity.
tools often are restricted in their application and consequently in their value for decision making, planning and control as they rely on simplified models and single-domain approaches. It has been shown that the modelling language Modelica offers novel possibilities in simulating and optimizing energy systems. Our framework and the included methods provide a major step forward as fully dynamic, thermo-hydraulic investigations of district heating and cooling systems are enabled. In our future research, we intend to integrate detailed models of other domains (e.g. power systems) and implement an interface to CAD and GIS. Science for society? An unbiased comparison of different systems can counteract developments that can be seen not only in various industries but also within academia: The vision of the energy transition is used by many actors to place and consolidate economic interests and to legitimize particular research fields. References: • Schweiger et al. “District heating and cooling systems – Framework for Modelica-based simulation and dynamic optimization,” Energy, 2017. • Schweiger et al. “Framework for dynamic optimization of district heating systems using Optimica Compiler Toolkit,” 12th International Modelica Conference, 2017. • Wetter, van Treeck: “BIM/GIS and Modelica Framework forbuilding and community energy system design and operation.” Presentation of IBPSA Project 1, 2016.
Acknowledgments Special thanks to Stéphane Velut, Per-Ola Larsson, Ingo Leusbrock and Franz Mauthner. The research leading to these results has been supported by Modelon AB and received funding from the Research Studio Austria no. 844732. The prize Gerald Schweiger won the 5th International DHC+ Student Awards. He was invited to present his research outcomes at the 38th Euroheat & Power Congress in Glasgow; furthermore, he received a coaching session from David Beckett (a pitch trainer and TEDx speech coach) and a research contribution of EUR 1000.
For further information please contact:
AEE - Institut für Nachhaltige Technologien Att.: MA Gerald Schweiger Feldgasse 19 A-8200 Gleisdorf, Austria
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