Implementation of thermal network simulation in operation optimization of an energy system

Developing new technologies and promoting a more rational use of sources are the main tasks addressed in the energy field for fighting climate changes. Concerning the latter one, energy systems composed by different technologies interacting between them to perform a combined production of multiple energy vectors are studied with increasing interest. Higher production efficiencies, compensation of renewable sources oscillations, and increasing flexibility in power generation are some of their potentialities. However, planning their operation is a complex optimization task since many aspects must be included to build the model. High problem dimensions can be easily reached, constituting a challenge for commercial solvers. Including a simulation of the thermal network based on temperatures and flowrates in the optimization allows to achieve some important goals. In addition, when operating temperatures are considered, their effect on components' performance should be included as well. As an attempt to investigate these issues, the present study proposes a model for the integration of a thermal network in the operation optimization of an energy system. The model is based on an iterative process in which the operating powers and the thermal network are separately optimized. The mathematical formulation is kept as simple as possible (MILP for the energy system and QCQP for the heating network) and the result obtained is a near-optimal solution. One of the most important advantages of the model is the non-demanding computational time requested to find the solution, whose quality is demonstrated to be high despite not being a global optimum.