TY - CHAP A1 - Grote-Ramm, Wolfgang A1 - Schönig, Felix A1 - Schwarzbözl, Peter A1 - Drexelius, Maximilian A1 - Maldonado Quinto, Daniel A1 - Binder, Matthias T1 - Model Predictive Control and Service Life Monitoring for Molten Salt Solar Power Towers T2 - 29th SolarPACES Conference, Sydney N2 - A two-component system for control and monitoring of solar power towers with molten salt receivers is proposed. The control component consists of a model predictive control applica-tion (MPC) with a flexible objective function and on-line tunable weights, which runs on a In-dustrial PC and uses a reduced order dynamic model of the receiver’s thermal and flow dy-namics. The second component consists of a service-life monitoring unit, which estimates the service-life consumption of the absorber tubes depending on the current mode of operation based on thermal stresses and creep fatigue in the high temperature regime. The calculation of stresses is done based on a detailed finite element study, in which a digital twin of the re-ceiver was developed. By parallelising the model solver, the estimation of service-life con-sumption became capable of real-time operation. The system has been implemented at a test facility in Jülich, Germany, and awaits field experiments. In this paper, the modeling and archi-tecture are presented along simulation results, which were validated on a hardware-in-the-loop test bench. The MPC showed good disturbance rejection while respecting process variable constraints during the simulation studies. KW - Solar Power Tower KW - Molten Salt KW - Model Predictive Control KW - Dynamic Modelling KW - Service-life Monitoring Y1 - 2023 N1 - Eingereichter Beitrag ER - TY - JOUR A1 - Uffmann, Kai A1 - Abicht, Claus A1 - Grote, Wolfgang A1 - Quick, Harald H. A1 - Ladd, Mark E. T1 - Design of an MR-compatible piezoelectric actuator for MR elastography JF - Concepts in Magnetic Resonance Part A: Bridging Education and Research N2 - Magnetic Resonance (MR) elastography is a method for measuring tissue elasticity via phase images acquired with an MR scanner. The propagation of periodic mechanical waves through the tissue can be captured by means of a modified phase contrast sequence. These waves are generated with a mechanical oscillator (actuator) and coupled into the tissue through the skin. The actuator must be capable of generating a sinusoidal excitation with excellent phase and amplitude stability, while not disturbing the MR imaging process. In this work, an actuator based on a piezoelectric principle was developed. Based on the imaging evaluation of several material samples, the housing for the piezoelectric ceramic was constructed of aluminum. Smaller parts of the housing were manufactured from brass and titanium to fulfill the mechanical constraints. A lever was used to transfer the oscillation generated by the piezoelectric ceramic to the point of excitation. The lever amplifies the piezoelectric motion, allowing for a more compact design. Three different lever designs were characterized by an acceleration sensor both outside and inside the magnet. It was shown that the rigidity of the lever, as determined by its material and form, was decisive in determining the resonant frequency of the system and therefore the maximum practical frequency of operation. It was also shown that the motion of the oscillator is unaffected by the electromagnetic fields of the MR imager. The final design can be placed directly in the magnet bore within a few centimeters of the tissue volume to be imaged without generating significant artifacts. An amplitude range of 0–1 mm in the frequency range from 0 to over 300 Hz was achieved, sufficient for performing most MR elastography applications. © 2002 Wiley Periodicals, Inc. Concepts in Magnetic Resonance (Magn Reson Engineering) 15: 239–254, 2002 KW - Elasticity KW - Elastography KW - Actuator KW - MRI KW - Piezoelectric Y1 - 2002 UR - 1552-5023 U6 - https://doi.org/https://doi.org/10.1002/cmr.10045 VL - 15 IS - 4 SP - 239 EP - 254 PB - Wiley ER - TY - JOUR A1 - Galban, Craig A1 - Maderwald, Stefan A1 - Herrmann, Burkhard A1 - Brauck, K. A1 - Grote, Wolfgang A1 - de Greiff, A. A1 - Uffmann, K. A1 - Ladd, M. T1 - Measuring Skeletal Muscle Elasticity in Patients with Hypogonadism by MR Elastography JF - Proc. Intl. Soc. Mag. Reson. Med. N2 - Men afflicted with hypogonadism have reduced fat-free mass and in some cases a loss in muscle strength. We hypothesize that muscle elasticity of the lower extremities differs between patients with hypogonadism and healthy controls. The shear modulus of the soleus muscle was measured non-invasively using MR elastography (MRE) at 0%, 5%, 10%, 15%, and 20% of the subject’s maximum applied force. The results from this study showed statistical differences between the patients and controls, even though there were no statistical differences in applied force. Y1 - 2005 UR - https://cds.ismrm.org/protected/05MProceedings/PDFfiles/02016.pdf VL - 13 SP - 2016 ER - TY - JOUR A1 - Galban, Craig A1 - Maderwald, Stefan A1 - Eggebrecht, Holger A1 - Grote, Wolfgang A1 - de Greiff, A. A1 - Uffmann, K. A1 - Ladd, M. E. T1 - Monitoring the Effects of Chronic Obstructive Pulmonary Disease on Muscle Elasticity by MR Elastography JF - Proc. Intl. Soc. Mag. Reson. Med. N2 - Men afflicted with chronic obstructive pulmonary disease (COPD) show signs of muscle dysfunction, such as increased muscle fatigue and acidosis during exercise. We hypothesize that muscle elasticity of the lower extremities differs between patients with COPD and age-related controls. The shear modulus of the soleus muscle was measured non-invasively using MR elastography (MRE) at 0%, 5%, 10%, 15%, and 20% of the subject’s maximum applied force. The results from this study showed statistical differences between the patients and controls, even though there were no statistical differences in the maximum applied force. Y1 - 2005 UR - https://cds.ismrm.org/protected/05MProceedings/PDFfiles/02015.pdf VL - 13 SP - 2015 ER - TY - JOUR A1 - Beyer, Marc-André A1 - Grote, Wolfgang A1 - Reinig, Gunter T1 - Adaptive exact linearization control of batch polymerization reactors using a Sigma-Point Kalman Filter JF - Journal of Process Control N2 - The Chylla–Haase polymerization reactor is widely accepted as a benchmark process for the evaluation of control strategies for batch reactors. In this contribution a control concept based on Exact I/O-Linearization is proposed and compared to a conventional cascade control structure. In order to adapt the exact linearization control strategy to various polymerization products and batch conditions, an advanced probabilistic inference algorithm (Sigma-Point Kalman Filter) is applied and investigated. Sigma-Point Kalman Filters have the major improvement of simplified implementation compared to local linearization methods (i.e. Extended Kalman Filter) because no analytical Jacobians are required. Stochastic simulation studies are introduced and show the effectiveness, accuracy and benefit of the control concept. Within several scenarios a satisfying robustness against structural errors in the underlying model equations for the nonlinear control law and the inference algorithm is demonstrated. Furthermore it is pointed out, that with little effort in reassembling the plant design, control performance can be improved significantly. KW - Batch process operation KW - Exact I/O-Linearization control KW - Online parameter estimation KW - Sigma-Point Kalman Filter Y1 - 2008 UR - 1873-2771 U6 - https://doi.org/10.1016/j.jprocont.2007.12.002 VL - 18 IS - 7-8 SP - 663 EP - 675 PB - Elsevier ER - TY - THES A1 - Grote, Wolfgang T1 - Ein Beitrag zur modellbasierten Regelung von Entnahmedampfturbinen KW - Dynamische Modellierung KW - Dampfturbine KW - Prädiktive Regelung KW - Dampfkraftwerk Y1 - 2009 UR - https://hss-opus.ub.ruhr-uni-bochum.de/opus4/2109 PB - Bochum ER - TY - CHAP A1 - Grote, Wolfgang A1 - Schulze Darup, M. A1 - Reinig, G. T1 - Modellprädiktive Regelung von Entnahmeturbinen und Dampfnetzen (Poster) T2 - Chemie Ingenieur Technik Y1 - 2009 U6 - https://doi.org/10.1002/cite.200950184 VL - 2009 IS - 8 SP - 1113 EP - 1114 PB - Wiley CY - Weinheim ER - TY - CHAP A1 - Grote, Wolfgang A1 - Reinig, Gunter T1 - Modellbasierte Regelung von Entnahmedampfturbinen (eingeladener Vortrag) T2 - 43. Regelungstechnisches Kolloquium in Boppard vom 25.-27. Februar 2009 KW - Modellierung von Dampfturbinen KW - Modellprädiktive Regelung KW - Generische Modelle KW - MIMO Regelung KW - Betriebsartenspezifische Regelung Y1 - 2009 UR - https://www.iosb.fraunhofer.de/content/dam/iosb/iosbtest/documents/veranstaltungen/boppard-regelungstechnisches-kolloquium/Programm_2009.pdf ER - TY - CHAP A1 - Grote, Wolfgang A1 - Kastsian, Darya A1 - Mönnigmann, Martin T1 - Optimal power system unit commitment with guaranteed local stability T2 - Proceedings of the 2011 American Control Conference N2 - This article deals with the cost optimal commitment of power systems. System stability is often only considered after solving the commitment problem. We show by example that a cost optimization may result in a mode of operation that, while economically optimal, is unstable or has otherwise unacceptable dynamics. As a remedy, we propose to use the so-called normal vector method, which has been developed for the optimization of nonlinear dynamical systems with stability boundaries and uncertain parameters. We apply the method to a small sample power grid, where the optimization goal is to minimize the energy production costs for a given power consumption. KW - Optimization KW - Power system stability KW - Robustness Y1 - 2011 U6 - https://doi.org/10.1109/ACC.2011.5991058 SN - 2378-5861 SP - 4526 EP - 4531 PB - IEEE ER - TY - JOUR A1 - Grote, Wolfgang A1 - Kastsian, Darya A1 - Mönnigmann, Martin T1 - Guaranteed stability in optimal power generation dispatching under uncertainty JF - IEEE Transactions on Power Systems N2 - Stability and cost optimality of power generation and supply systems must not be considered independently from one another. Simple examples show that optimizing cost without considering stability may result in modes of operation that, while economically optimal, are unstable. We demonstrate that stability, robustness, and optimality can be considered systematically and simultaneously by combining bifurcation theory and nonlinear optimization. Essentially, the proposed method enforces a backoff distance between the optimal point of operation and operational or stability boundaries in the space of the optimization variables, where bifurcation theory is used to describe nonlinear stability boundaries. KW - Normal vector method KW - Power dispatch KW - Robust optimization KW - Stability KW - Unit commitment Y1 - 2013 U6 - https://doi.org/10.1109/TPWRS.2012.2207970 SN - 1558-0679 VL - 28 IS - 2 SP - 1103 EP - 1112 PB - IEEE ER -