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Order reduction for nonlinear dynamic models of district heating networks

: Rein, Markus
: Klar, A.; Marheineke, N.

Volltext urn:nbn:de:0011-n-5901283 (1.6 MByte PDF)
MD5 Fingerprint: a61505af044bddba989fbf4917cba85c
Erstellt am: 27.5.2020

Stuttgart: Fraunhofer Verlag, 2020, X, 138 S.
Zugl.: Kaiserslautern, TU, Diss., 2019
ISBN: 978-3-8396-1581-2
Dissertation, Elektronische Publikation
Fraunhofer ITWM ()
numerical analysis; heat transfer processes; optimization; district heating network; model order reduction; optimal control applications; linear time-varying systems; Lyapunov stability; angewandte Mathematiker; Energieingenieur; Berechnungsingenieur

This thesis focuses on the formulation of reduced order models for a numerically efficient simulation of district heating networks. Their dynamics base upon incompressible Euler equations, forming a system of quasi-linear hyperbolic partial differential equations. The algebraic constraints introduced by the network structure cause dynamical changes of flow direction as a central difficulty. A control system is derived allowing to analyze essential properties of the reduced order model such as Lyapunov stability. By splitting the problem into a differential part describing the transport of thermal energy and an algebraic part defining the flow field, tools from parametric model order reduction can be applied. A strategy is suggested which produces a global Galerkin projection based on moment-matching of local transfer functions. The benefits of the resulting surrogate model are demonstrated at different, existing large-scale networks. In addition, the performance of the suggested model is studied in the numerical computation of an optimal control of the feed-in power employing a discretize-first strategy.