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Analysis of Anti-surge control Method for Axial Flow Compressor

外文科技期刊数据库(文摘版)工程技术 2021年第6期 417-418页

作者： CHEN Hongxin CHEN Sishi Shenyang Blower Group Automatic Control System Engineering Co. Ltd. Shenyang 110000 China

With the continuous development of society, axial compressor has been more and more widely used in modern industry. The surge motion of axial compressor has gradually attracted people's attention. It is necessary to actively explore the anti surge control method of axial compressor. In this paper, the surge control method of fully static regulating axial compressor is analyzed, and the surge control of axial compressor is realized by using programmable controller, which solves the shortcomings of existing control methods, improves the operation condition and improves the efficiency of axial compressor.

关键词： axial flow compressor anti-surge control method implementation

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Detection and classification of turn fault and high-resistance connection fault in inverter-fed permanent magnet machines based on high-frequency signals

Detection and classification of turn fault and high-resistan...

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作者： Hu, Rongguang Wang, Jiabin Mills, Andrew Chong, Ellis Sun, Zhigang Department of Electronics and Electrical Engineering University of Sheffield Sheffield United Kingdom Department of Automatic Control and System Engineering University of Sheffield Sheffield United Kingdom Electrical Capability Group Rolls-Royce plc Derby United Kingdom

Winding turn fault and high-resistance connection (HRC) fault will lead to different consequences and require different mitigation actions. In this study, the differentiating features between a turn fault and HRC fault are analysed and compared in a three-phase surface-mounted permanent magnet machine fed by the inverter with pulse-width-modulation voltages. The resultant high-frequency components in both voltages and currents are utilised for the fault detection and classification based on the high-frequency impedance and ripple current, without requiring modifications to the machine or interface design. Extensive simulations show that this method is capable of fault detection and classification in both transient and steady-state operations. © 2019 Institution of engineering and Technology. All rights reserved.

关键词： Permanent magnets

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The importance of horizontal Poynting flux in the solar photosphere

arXiv

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arXiv 2022年

作者： Silva, Suzana S.A. Murabito, Mariarita Jafarzadeh, Shahin Stangliani, Marco Verth, Gary Ballai, Istvan Fedun, Viktor Plasma Dynamics Group Department of Automatic Control and Systems Engineering University of Sheffield Sheffield United Kingdom Department of Physics Aeronautics Institute of Technology São José dos Campos Brazil INAF - Osservatorio Astronomico di Roma Via Frascati33 Monte Porzio Catone RM 00078 Italy Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany Rosseland Centre for Solar Physics University of Oslo P.O. Box 1029 Blindern OsloNO-0315 Norway ASI Italian Space Agency Via del Politecnico snc Rome00133 Italy Plasma Dynamics Group School of Mathematics and Statistics University of Sheffield Sheffield United Kingdom

The electromagnetic energy flux in the lower atmosphere of the Sun is a key tool to describe the energy balance of the solar atmosphere. Current investigations on energy flux in the solar atmosphere focus primarily on the vertical electromagnetic flux through the photosphere, ignoring the Poynting flux in other directions and its possible contributions to local heating. Based on a realistic Bifrost simulation of a quiet-Sun (coronal hole) atmosphere, we find that the total electromagnetic energy flux in the photosphere occurs mainly parallel to the photosphere, concentrating in small regions along intergranular lanes. Thereby, it was possible to define a proxy for this energy flux based on only variables that can be promptly retrieved from observations, namely, horizontal velocities of the small-scale magnetic elements and their longitudinal magnetic flux. Our proxy accurately describes the actual Poynting flux distribution in the simulations, with the electromagnetic energy flux reaching 1010 erg cm−2 s−1. To validate our findings, we extended the analysis to SUNRISE/IMaX data. First, we show that Bifrost realistically describes photospheric quiet-Sun regions, as the simulation presents similar distributions for line-of-sight magnetic flux and horizontal velocity field. Second, we found very similar horizontal Poynting flux proxy distributions for the simulated photosphere and observational data. Our results also indicate that the horizontal Poynting flux in the observations is considerably larger than the vertical electromagnetic flux from previous observational estimates. Therefore, our analysis confirms that the electromagnetic energy flux in the photosphere is mainly horizontal and is most intense in localized regions along intergranular lanes. Copyright © 2022, The Authors. All rights reserved.

关键词： Magnetohydrodynamics

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Unexpected frequency of horizontal oscillations of magnetic structures in the solar photosphere

arXiv

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arXiv 2024年

作者： Berretti, M. Stangalini, M. Verth, G. Jafarzadeh, S. Jess, D.B. Berrilli, F. Grant, S.D.T. Duckenfield, T. Fedun, V. University of Trento Via Calepina 14 Trento38122 Italy University of Rome Tor Vergata Department of Physics Via della Ricerca Scientifica 3 Rome00133 Italy ASI Italian Space Agency Via del Politecnico snc Rome00133 Italy Plasma Dynamics Group School of Mathematics and Statistics The University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany Niels Bohr International Academy Niels Bohr Institute Blegdamsvej 17 CopenhagenDK-2100 Denmark Astrophysics Research Centre School of Mathematics and Physics Queen’s University Belfast Northern Ireland BelfastBT7 1NN United Kingdom Department of Physics and Astronomy California State University Northridge NorthridgeCA91330 United States Plasma Dynamics Group Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom

It is well known that the dominant frequency of oscillations in the solar photosphere is ≈3 mHz, which is the result of global resonant modes pertaining to the whole stellar structure. However, analyses of the horizontal motions of nearly 1 million photospheric magnetic elements spanning the entirety of solar cycle 24 have revealed an unexpected dominant frequency, ≈5 mHz, a frequency typically synonymous with the chromosphere. Given the distinctly different physical properties of the magnetic elements examined in our statistical sample, when compared to largely quiescent solar plasma where ≈3 mHz frequencies are omnipresent, we argue that the dominant ≈5 mHz frequency is not caused by the buffeting of magnetic elements, but instead is due to the nature of the underlying oscillatory driver itself. This novel result was obtained by exploiting the unmatched spatial and temporal coverage of magnetograms acquired by the Helioseismic and Magnetic Imager (HMI) on board NASA’s Solar Dynamics Observatory (SDO). Our findings provide a timely avenue for future exploration of the magnetic connectivity between sub-photospheric, photospheric, and chromospheric layers of the Sun’s dynamic atmosphere. Copyright © 2024, The Authors. All rights reserved.

关键词： Magnetic structure

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Sausage, kink, and fluting MHD wave modes identified in solar magnetic pores by Solar Orbiter/PHI

arXiv

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arXiv 2024年

作者： Jafarzadeh, S. Schiavo, L.A.C.A. Fedun, V. Solanki, S.K. Stangalini, M. Calchetti, D. Verth, G. Jess, D.B. Grant, S.D.T. Ballai, I. Gafeira, R. Keys, P.H. Fleck, B. Morton, R.J. Browning, P.K. Silva, S.S.A. Appourchaux, T. Gandorfer, A. Gizon, L. Hirzberger, J. Kahil, F. Suárez, D. Orozco Schou, J. Strecker, H. del Toro Iniesta, J.C. Valori, G. Volkmer, R. Woch, J. Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany School of Physics & Astronomy The University of Manchester Oxford Road ManchesterM13 9PL United Kingdom Department of Mathematics Physics and Electrical Engineering Northumbria University Newcastle upon TyneNE1 8ST United Kingdom Plasma Dynamics Group Department of Automatic Control and Systems Engineering The University of Sheffield Mappin Street SheffieldS1 3JD United Kingdom ASI Italian Space Agency Via del Politecnico snc RomeI-00133 Italy Plasma Dynamics Group School of Mathematics and Statistics The University of Sheffield Hicks Building Hounsfield Road SheffieldS3 7RH United Kingdom Astrophysics Research Centre School of Mathematics and Physics Queen’s University Belfast BelfastBT7 1NN United Kingdom Department of Physics and Astronomy California State University Northridge NorthridgeCA91330 United States Instituto de Astrofísica e Ciências do Espaço Department of Physics University of Coimbra Coimbra3040-004 Portugal ESA Science and Operations Department c/o NASA Goddard Space Flight Center GreenbeltMD20771 United States Univ. Paris-Sud Institut d’Astrophysique Spatiale UMR 8617 CNRS Bâtiment 121 Orsay91405 Cedex France Apartado de Correos 3004 GranadaE-18080 Spain Leibniz-Institut für Sonnenphysik Schöneckstr. 6 FreiburgD-79104 Germany Institut für Astrophysik und Geophysik Georg-August-Universität Göttingen Friedrich-Hund-Platz 1 Göttingen37077 Germany

Solar pores are intense concentrations of magnetic flux that emerge through the Sun’s photosphere. When compared to sunspots, they are much smaller in diameter and hence can be impacted and buffeted by neighbouring granular activity to generate significant magnetohydrodynamic (MHD) wave energy flux within their confines. However, observations of solar pores from ground-based telescope facilities may struggle to capture subtle motions synonymous with higher-order MHD wave signatures due to seeing effects produced in the Earth’s atmosphere. Hence, we have exploited timely seeing-free and high-quality observations of four small magnetic pores from the High Resolution Telescope (HRT) of the Polarimetric and Helioseismic Imager (PHI) on board the Solar Orbiter spacecraft, during its first close perihelion passage in March 2022 (at a distance of 0.5 au from the Sun). Through acquisition of data under stable observing conditions, we have been able to measure the area fluctuations and horizontal displacements of the solar pores. Cross correlations between perturbations in intensity, area, line-of-sight velocity, and magnetic fields, coupled with the first-time application of novel Proper Orthogonal Decomposition (POD) techniques on the boundary oscillations, provide a comprehensive diagnosis of the embedded MHD waves as sausage and kink modes. Additionally, the previously elusive m = 2 fluting mode is identified in the most magnetically isolated of the four pores. An important consideration lies in how the identified wave modes contribute towards the transfer of energy into the upper solar atmosphere. We find that the four pores examined have approximately 56%, 72%, 52%, and 34% of their total wave energy associated with the identified sausage modes, and around 23%, 17%, 39%, and 49% to their kink modes, respectively, while the first pore also has around an 11% contribution linked to the fluting mode. This study marks the first-time identification of concurrent sausage, kin

关键词： Magnetohydrodynamics

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Numerical Evaluation of a Robust Self-Triggered MPC Algorithm

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IFAC-PapersOnLine 2016年第22期49卷 151-156页

作者： Brunner, Florian D. Heemels, W.P.M.H. Allgöwer, Frank Institute for Systems Theory and Automatic Control University of Stuttgart Pfaffenwaldring 9 Stuttgart70569 Germany Control System Technology Group Department of Mechanical Engineering Eindhoven University of Technology Netherlands

We present numerical examples demonstrating the efficacy of a recently proposed self-triggered model predictive control scheme for disturbed linear discrete-time systems with hard constraints on the input and state. In order to reduce the amount of communication between the controller and the actuator, the control input is not re-computed at each point in time but only at certain sampling instances. These instances are determined in a self-triggered fashion in the sense that at every sampling instant the next sampling instant is computed as a function of the current system state. A compact set in the state space, whose size is a design parameter in the control scheme, is stabilized. © 2016

关键词： Discrete time control systems Digital control systems Model predictive control Predictive control systems Robustness (control systems) control inputs control schemes Design parameters Hard constraints Linear discrete time systems Predictive control Sampling instants Self triggered controls

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Robust Event-Triggered MPC for Constrained Linear Discrete-Time systems with Guaranteed Average Sampling Rate

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IFAC-PapersOnLine 2015年第23期48卷 117-122页

We propose a robust event-triggered model predictive control (MPC) scheme for linear time-invariant discrete-time systems subject to bounded additive stochastic disturbances and hard constraints on the input and state. For given probability distributions of the disturbances acting on the system, we design event conditions such that the average frequency of communication between the controller and the actuator in the closed-loop system attains a given value. We employ Tube MPC methods to guarantee robust constraint satisfaction and a robust asymptotic bound on the system state. Moreover, we show that based on a given periodically updated Tube MPC scheme, an appropriate event-triggered MPC scheme can be designed, with the same guarantees on constraints and region of attraction, but with a reduced number of average communications. © 2015, IFAC (International Federation of automatic control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Discrete time control systems Closed loop systems Digital control systems Linear control systems Model predictive control Predictive control systems Probability distributions Robustness (control systems) Stochastic models Stochastic systems Constraint Satisfaction Discrete time systems Event triggered controls Linear discrete time systems Linear time invariant Predictive control Region of attraction Stochastic disturbances

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Communication scheduling in robust self-triggered MPC for linear discrete-time systems 5

Communication scheduling in robust self-triggered MPC for li...

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5th IFAC Workshop on Distributed Estimation and control in Networked systems, NecSys 2015

作者： Brunner, Florian D. Gommans, T.M.P. Heemels, W.P.M.H. Allgöwer, Prank Institute for Systems Theory and Automatic Control University of Stuttgart Pfaffenwaldring 9 Stuttgart70569 Germany Control System Technology Group Department of Mechanical Engineering Eindhoven University of Technology Netherlands

We consider a networked control system consisting of a physical plant, an actuator, a sensor, and a controller that is connected to the actuator and sensor via a communication network. The plant is described by a linear discrete-time system subject to additive disturbances. In order to reduce the required number of communications in the system, we propose a robust self-triggered model predictive controller based on rollout techniques that robustly asymptotically stabilizes a certain periodic sequence of sets in the state space while guaranteeing robust satisfaction of hard state and input constraints. At periodically occurring scheduling times, the self-triggered model predictive control algorithm determines the times at which the control input and plant measurement are updated in the time span until the next scheduling time. We establish a certain upper bound on the average sampling rate in the closed-loop system. Moreover, we show how increasing the asymptotic bound on the system state, which is a design parameter in the control scheme, can be used to further reduce the average number of communications in the system. © 2015, IF AC (International Federation of automatic control) Hosting by Elsevier Ltd. All rights reserved.

关键词： Closed loop systems

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Communication Scheduling in Robust Self-Triggered MPC for Linear Discrete-Time systems ∗

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IFAC-PapersOnLine 2015年第22期48卷 132-137页

作者： Florian D. Brunner T.M.P. Gommans W.P.M.H. Heemels Frank Allgöwer Institute for Systems Theory and Automatic Control University of Stuttgart Pfaffenwaldring 9 70569 Stuttgart Germany Control System Technology Group Department of Mechanical Engineering Eindhoven University of Technology The Netherlands

关键词： predictive control self-triggered control robustness

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Resource-aware set-valued estimation for discrete-time linear systems

Resource-aware set-valued estimation for discrete-time linea...

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IEEE Annual Conference on Decision and control

作者： F. D. Brunner T. M. P. Gommans W. P. M. H. Heemels F. Allgowert Institute for Systems Theory and Automatic Control (IST) University of Stuttgart 70550 Stuttgart Germany Control System Technology group Department of Mechanical Engineering Eindhoven University of Technology

ISBN: (纸本)9781479978878

In this paper, we propose a self-triggered estimator for discrete-time linear systems subject to unknown but bounded disturbances affecting both the system states and outputs. The proposed self-triggered estimator is a set-valued estimator that employs rollout techniques to reduce the communication between the sensors and the estimator with respect to a periodic sampling strategy. Moreover, at each time instant it provides an estimate of the plant state and a guaranteed bound on the difference between the true plant state and the estimate.

关键词： Linear system discrete-time discrete time systems Unknown Sensors Communication Research

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