The bidirectional substation for district heating users: experimental performance assessment with operational profiles of prosumer loads and distributed generation.

• Experimental campaign performed to test the operation of a return-to-supply bidirectional substation. • Hardware-in-the-loop technique coupling in real-time realistic thermal load and production profiles. • Detailed tests for representative days, three case studies and extended assessment for the entire year. • Daily district heating contribution ranging between 21% and 100%. • Yearly local production contribution reaches 100% of the user's load, considering the net-metering. The regulatory European and national policies outline the role of efficient district heating in achieving mid and long-term decarbonization targets. Prosumers could be equipped with bidirectional exchange substations to increase the local production contribution. The present paper evaluates the contribution of a bidirectional substation in maximizing the use of thermal energy produced locally by renewable sources or waste heat in a densely populated area, considering the limitation due to the non-contemporaneity of production and consumption and possibilities to overcome them. The substation prototype and the control system were tested in operational conditions, assuming the district heating network operating at two temperature levels (80 °C/50 °C and 60 °C/30 °C for supply and return) and applying the hardware-in-the-loop technique for coupling the substation in real-time with data-driven thermal loads (multi-family residential building) and production (solar panels and waste heat) profiles. The various energy flows in the substation are presented for representative days, resulting in a district heating contribution to the user's load ranging between 99.8 % (winter day) and 21.8 % (summer day). The net-metering mechanism was considered, and the assessment extended to the entire year. The local production contribution to the user's load ranges between 24 % and 100 %, depending on the system configuration considered. [ABSTRACT FROM AUTHOR]