Session 4D: Control Systems I

Title: Framework for dynamic optimization of district heating systems using Optimica Compiler Toolkit
Authors: Gerald Schweiger, Håkan Runvik, Fredrik Magnusson, Per-Ola Larsson and Stéphane Velut
Abstract:Recent studies show that district heating infrastructures should play an important role in future sustainable energy systems. Tools for dynamic optimization are required to increase the efficiency of existing systems and design new ones. This paper presents a novel framework to represent, simplify, simulate and optimize district heating systems. The framework is implemented in Python and is based on Optimica Compiler Toolkit as well as Modelon's Thermal Power Library. The high-level description of optimization problems using Optimica allows flexible optimization formulations including constraints on physically relevant variables such as supply temperature, flow rate and pressures. The benefit of new algorithms for symbolic elimination in Optimica Compiler Toolkit is also investigated. The framework is applied on a test case, which is based on a planned city district located in Graz, Austria. The results demonstrate the generality of the representation as well as the accuracy of the simplification for dynamic optimization of temperature supply and pressure control.
Links: Full paper

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Title: Optimal Control of District Heating Systems using Dynamic Simulation and Mixed Integer Linear Programming
Authors: Loïc Giraud, Massinissa Merabet, Roland Baviere and Mathieu Vallée
Abstract:This paper presents the development of a new advanced control method suitable for variable temperature District Heating Systems (DHS). The proposed controller determines optimal planning for the on/off status and power of the heat generators as well as for the supply temperature and differential pressure at the production plant level. Compared to existing methods, the original features of the developed solution are to fully exploit the thermal storage capacity of the network and to determine the best compromise between pumping costs and heat losses. A numerical case study based on a representative DHS is used to evaluate the method over a heating season (5 months). Results show that our method reduces production costs up to 8.3 % when compared to a more classical controller. Moreover, the observed computational costs are compatible with the requirements of the receding time horizon principle, ensuring that the method is tractable on real DHS.
Links: Full paper

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Title: Rapid development of an aircraft cabin temperature regulation concept
Authors: Alexander Pollok, Daniel Bender, Ines Kerling and Dirk Zimmer
Abstract:The air in aircraft cabins is controlled for pressure, temperature and humidity. The number of temperature zones is generally kept low, for reasons of necessary ducting space. We devise a new ducting concept, which enables a large number of temperature zones. Controllability of the system is however predicted to be a potential obstacle. For a quick resolution of this question, a Modelica model is created. Model creation is focused on a short development time as well as usefulness for controller synthesis. A workflow is presented that enables a quick iteration time between controller synthesis in Matlab and controller testing in a Modelica environment. Finally, the impact of this new concept on the energy consumption of the air generation unit is discussed.
Links: Full paper

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Title: Investigation of the Influence of Controller Approaches on Room Thermal Behaviour A Simulation Study
Authors: Kristin Majetta, Christoph Clauss and Christoph Nytsch-Geusen
Abstract:To control the room temperature normally special developed and adapted controllers are used. This development is both time-consuming and expensive. Therefore, this paper shows the first steps to achieve the goal of developing a methodology to provide rules and guidelines for typical use cases of those controllers with regard to given rooms and their installed HVAC technology. Thereby it should be possible to choose suitable controllers for a wide range of rooms without the necessity of an expensive development process. To achieve this goal a simulation study will be performed. This paper presents first steps of this investigation. This includes the choice development of four different, representative room models as well as five controller models of important controller types. Simulations of well defined scenarios analyze the eligibility of the controller models regarding net energy consumption and comfort. First optimization results to improve the quality of the controllers are shown and further steps are explained.
Links: Full paper