Economic model predictive control for optimal operation of combined heat and power systems

© 2019. ElsevierThe use of decentralized Combined Heat and Power (CHP) plants is increasing since the high levels of efficiency they can achieve. Hence, to determine the optimal operation of these systems in the changing energy market, the time-varying price profiles for both electricity as well as the required resources and the energy-market constraints should be considered into the design of the control strategies. To solve these issues and maximize the profit during the operation of the CHP plant, this paper proposes an optimization-based controller, which will be designed according to the Economic Model Predictive Control (EMPC) approach. The proposed controller is designed considering a non-constant time step to get a high sampling frequency for the near instants and a lower resolution for the far instants. Besides, a soft constraint to met the market constraints for the sale of electric power is proposed. The proposed controller is developed based on a real CHP plant installed in the ETA research factory in Darmstadt, Germany. Simulation results show that lower computational time can be achieved if a non-constant step time is implemented while the market constraints are satisfied.Peer ReviewedPostprint (author's final draft

Optimal operation of combined heat and power systems: an optimization-based control strategy

The use of decentralized Combined Heat and Power (CHP) plants is increasing since the high levels of efficiency they can achieve. Thus, to determine the optimal operation of these systems in dynamic energy-market scenarios, operational constraints and the time-varying price profiles for both electricity and the required resources should be taken into account. In order to maximize the profit during the operation of the CHP plant, this paper proposes an optimization-based controller designed according to the Economic Model Predictive Control (EMPC) approach, which uses a non-constant time step along the prediction horizon to get a shorter step size at the beginning of that horizon while a lower resolution for the far instants. Besides, a softening of related constraints to meet the market requirements related to the sale of electric power to the grid point is proposed. Simulation results show that the computational burden to solve optimization problems in real time is reduced while minimizing operational costs and satisfying the market constraints. The proposed controller is developed based on a real CHP plant installed at the ETA research factory in Darmstadt, Germany.Peer ReviewedPostprint (author's final draft

Study on Action-Oriented Learning with a Learning Factory Approach

AbstractAn important pr erequisite for prospective competitive factories is an effective and enduring development of production-related competencies in today's universities for manufacturing engineering. Learning Factories are an ac tion-oriented approach for developing these competencies. They are highly authentic learning environments in which genuine products are manufactured in a simulated but life-like production setting. The study aims at investigating the learning success of engineering students in a Learning Factory. Results of a conducted experiment are presented and discussed giving proof to the hypotheses that students have a greater application-performance and a higher degree of action-substantiating knowledge after having attended an action-oriented learning event within the Learning Factory than after receiving a conventional treatment

Energy efficient machine tools

The growing global energy demand from industry results in significant ecological and economical costs. Aiming to decrease the impact of machining operations, an increasing number of research activities and publications regarding energy efficient machine tools and machining processes can be found in the literature. This keynote paper provides an overview of current machine- and process-related measures to improve the energy efficiency of metal cutting machine tools. Based on an analysis of the energy requirements of machine tool components, design measures to reduce the energy demand of main and support units are introduced. Next, methods for an energy efficient operation of machine tools are reviewed. Furthermore, latest developments and already available energy efficiency options in the machine tool industry are discussed. The paper concludes with recommendations and future research questions for more energy efficient machine tools

Структура и свойства керамического композиционного материала ZrO[2](MgO)-MgO с бимодальной пористостью

In this paper, different implementations of elastic joint models of industrial robots are described and compared established in ADAMS and SimMechanics. The models are intended to be used for path prediction under process force load due to Roboforming and High Speed Cutting, respectively. The computational results have been compared and showed good agreement. In experiments of robot forming and robot milling the measured and simulated path deviations according to the process force are compared. The experiments are descriped and the results are discussed within the paper as a basis of a next step model based compensation of the path deviation

The antinucleon-nucleon interaction at low energy : annihilation dynamics

The general properties of antiproton-proton annihilation at rest are presented, with special focus on the two-meson final states. The data exhibit remarkable dynamical selection rules : some allowed annihilation modes are suppressed by one order of magnitude with respect to modes of comparable phase-space. Various phenomenological analyses are reviewed, based on microscopic quark dynamics or symmetry considerations. The role of initial- and final-state interaction is also examined.Comment: 128 pages, 49 tables, 27 figure

Untersuchung der Möglichkeiten einer Online-Qualitätsüberwachung (Quality Monitoring) basierend auf Maschinendaten

Die Qualitätsüberwachung in Unternehmen ist heute von größter Bedeutung. Bei der Bearbeitung von Werkstücken können sowohl im Ausgangsmaterial als auch während der Bearbeitung Fehler auftreten. Um diese Fehler zu detektieren können Monitoring-Systeme genutzt werden

A Generic Data Model for Describing Flexibility in Power Markets

In this article, we present a new descriptive model for industrial flexibility with respect to power consumption. The advancing digitization in the energy sector opens up new possibilities for utilizing and automatizing the marketing of flexibility potentials and therefore facilitates a more advanced energy management. This requires a standardized description and modeling of power-related flexibility. The data model in this work has been developed in close collaboration with several partners from different industries in the context of a major German research project. A suitable set of key figures allows for also describing complex production processes that exhibit interdependencies and storage-like properties. The data model can be applied to other areas as well, e.g., power plants, plug-in electric vehicles, or power-related flexibility of households

A Framework for Self-Evaluation and Increase of Resource-Efficient Production through Digitalization

Modern sensor technology and decreasing hardware costs enable the collection of a wide range of data. Nonetheless, the collection of data itself does not generate value. The collected data must be processed and analysed. Many small and medium-sized enterprises already collect a number of data. However, there is no definite strategy, which data needs to be collected in order to acquire relevant insights into processes. The enormous potential of data analysis and the current lack of its implementation caused the development of this framework. It will assist enterprises to evaluate their own level of digitalization to assess resource use

Influence of LPBF-Surface Characteristics on Fatigue Properties of Scalmalloy®

Laser powder bed fusion (LPBF) has indisputable advantages when designing new components with complex geometries due to toolless manufacturing and the ability to manufacture components with undercuts. However, fatigue properties rely heavily on the surface condition. In this work, in-process surface parameters (three differing contour parameter sets) and post-process surface treatments, namely turning and shot peening, are varied to investigate the influence of each treatment on the resulting fatigue properties of LPBF-manufactured specimens of the aluminium–magnesium–scandium alloy Scalmalloy®. Therefore, metallographic analysis and surface roughness measurements, as well as residual stress measurements, computer tomography measurements, SEM-analyses, tensile and fatigue tests, along with fracture surface analysis, were performed. Despite the fact that newly developed in-process contour parameters are able to reduce the surface roughness significantly, only a minor improvement in fatigue properties could be observed: Crack initiation is caused by sharp, microscopic notches at the surface in combination with high tensile residual stresses at the surface, which are present on all in-process contour parameter specimens. Specimens using contour parameters with high line energy show keyhole pores localized in the subsurface area, which have no effect on crack initiation. Contours with low line energy have a slightly positive effect on fatigue strength because less pores can be found at the surface and subsurface area, which even more greatly promotes an early crack initiation. The post-process parameter sets, turning and shot peening, both improve fatigue behaviour significantly: Turned specimens show lowest surface roughness, while, for shot peened specimens, the tensile residual stresses of the surface radially shifted from the surface towards the centre of the specimens, which counteracts the crack initiation at the surface