Control-Oriented Modeling, Simulation, and Predictive Control of District Heating Networks

District heating networks (DHNs) are recognized as pivotal infrastructures to reduce the carbon footprint of the heating sector. However, their large-scale dimension and the involved nonlinear dynamics lead to significant issues regarding their modeling and optimal control. Tackling these challenges, two dynamic DHN modeling frameworks are presented: a detailed simulation model and a control-oriented one. The simulation model allows the development of lightweight dynamic DHN simulators, accurately represents the main system dynamics in reduced computational time, and is well-suited for testing online control algorithms. This model is leveraged to develop a simulation library for DHN systems in the Modelica environment, named DHN4Control, freely distributed with this article in Nigro (2023). Then, a methodology for deriving a control-oriented DHN model is presented, suitable for designing a nonlinear model predictive control (NMPC) regulator, ensuring computationally efficient and cost-effective regulation while respecting operative constraints. The developed modeling and control methods are tested in simulation considering as benchmark a Test Facility district heating plant located at Ricerca sul Sistema Energetico - RSE S.p.A. in Milan (Italy), showing promising results in terms of modelling accuracy, computational efficiency and energy savings. Note to Practitioners—The dimension and complexity of multi-producer district heating networks (DHN) make their modeling, simulation, and online optimization challenging tasks. This work proposes a solution for district heating networks efficient simulation and optimal control design. The detailed explanations of the modelling equations and the use of open source software increase results replicability for practitioners. The simulation-oriented model comes with a lightweight simulation library, readily available at Nigro (2023). The control-oriented model is reusable on generic multi-producer district heating networks, for computationally efficient optimization-based control design. The optimal control is able to manage thermal generators and storages to minimize DHN operational costs while respecting operational constraints over the whole thermal network. The proposed solution is tested in simulation considering a real-world DHN plant currently under construction at Ricerca sul Sistema Energetico - RSE S.p.A in Milan (Italy). The simulation results show the cost saving performances of optimal controllers developed with the proposed model. Overall, by using the proposed solution, one can achieve faster simulation times and ease the burden of optimal control modelling for the development of an optimal-based control strategy for cost-effective DHN operation.