Characterization of Photovoltaic systems for Large Scale Solar Power Generation

Séminaire le 17 Décembre 2015, 16h00 à CentraleSupelec (Gif-sur-Yvette) Salle du conseil du L2S - B4.40
Fernando Mancilla-David


Photovoltaic electric power generation is increasingly attracting the attention of industry and academia mainly motivated by the urgent need to depart from fossil fuel-based electricity generation. As the cost of PV panels production continues to decrease, it is expected that bulk solar power generation will be competitive with other forms of renewable energy, and hence massively deployed. Grid-connected PV power plants are currently generating up to a few megawatts as a single unit, and built through PV arrays containing hundreds of thousands of solar cells. The PV plant is connected to the ac grid via a power electronics-based interphase realized through a voltage source inverter.

The seminar presents research conducted at the University of Colorado Denver on the modeling and control of this type of systems, often referred to as large PV power plants. The modeling of the various elements making up a large PV power plant, namely PV cells, inverter and an equivalent of the ac grid, will be discussed. Furthermore, the seminar addresses the PV array's maximum power point tracking and the regulation of current injection into the ac grid. Considerations regarding the identification of solar irradiance are also to be discussed. The modeling and control techniques presented within the seminar are validated through computer simulations and/or experimentation performed in the University of Colorado Denver campus.

Biography

Fernando Mancilla-David is an Associate Professor at the University of Colorado Denver, where he teaches and directs research in energy and power systems as a faculty member of the Electrical Engineering Department. Prof. Mancilla-David received the B.S. degree in electrical engineering from the Universidad Tecnica Federico Santa Maria, Valparaiso, Chile, in 1999, and the M.S. and Ph.D. degrees in electrical engineering from the University of Wisconsin-Madison, Madison, Wisconsin, United State of America, in 2002 and 2007, respectively. He has been a visiting professor in several universities in Europe and has coauthored more than 60 technical articles, mostly in the area of utility applications of power electronics.

Pseudorational transfer functions and their spectral properties - an introductory survey

Séminaire le 15 Octobre 2015, 14h30 à CentraleSupelec (Gif-sur-Yvette) Salle du conseil du L2S - B4.40
Yutaka Yamamoto, univ of Kyoto


This talk gives an overview of the class of pseudorational transfer functions. This class consists of the ratio of entire functions of exponential type that are Laplace transforms of distributions with compact support. It gives rise to a convenient platform for dealing with distributed parameter systems whose state space is determined by bounded-time data.  Delay-differential systems, with retarded, neutral or distributed delays, are typical examples. We explore its interesting interplay with the ring of entire functions, and highlight some appealing structures as follows: Starting from a completely general input/output framework, we derive a concrete realization procedure based on the above fractional representation of transfer functions (or impulse responses).  It is then also possible to give a complete characterization of spectral properties of such realizations via zeros of the denominator of transfer functions.
Such spectral properties allow us to give a stability criterion and also an appropriate relationship between internal and external stability notions. Based on a concrete representation of the state space, we are led to a concrete characterization of left-shift invariant subspaces of H^2.  This result has a direct consequence on H-infinity control theory.
We also give a concise yet comprehensive and unified overview of such results.  The talk is concluded with this and also a criterion on the existence of a Bezout identity in this class.

Dynamics and Control of Inverted Ultra-Flexible Pendulum on Cart System

Séminaire le 29 Juin 2015, 16h00 à CentraleSupelec (Gif-sur-Yvette) Amphi Blondel
Prof. Prasanna S. Gandhi


Ultra-flexible beams are useful in several flexible mechanisms having applications, for example, in high-precision positioning systems and flexible link robotic systems. They demonstrate interesting dynamics, especially when these systems are in a vertical plane. This talk focuses on a representative of such system: a vertical, large-deformation cantilever with tip mass and actuated at fixed base by a cart. The system is shown to demonstrate multiple equilibria as a function of tip mass using elastica theory. Dynamics of this system is further captured using assumed modes method and imposing length constraint to model potential energy change of tip mass (constrained Langrange formulation). Evolution of chaotic behaviour under harmonic excitation is presented in comparison with experiments. We further develop a nonlinear nested saturations based controller for stabilising the cantilever in central unstable equilibrium with cart also reaching the desired position. Multiple coordinate transformations are performed to obtain a system in feedforward chain of integrators before applying nested saturation based control. Effectiveness of control is established through simulation cases and experimental implementation.

Biography: P.S. Gandhi received the B.Eng. degree in from the University of Bombay, Mumbai in 1994 and the M.Tech degree from the Indian Institute of Technology, Bombay, Mumbai in 1996, both in mechanical engineering. He received the Ph.D. degree in mechanical engineering from the Rice University, Houston in 2001. Since 2001, he has been faculty member, currently Professor, in the Department of Mechanical Engineering at Indian Institute of Technology, Bombay, Mumbai. His research interests are in the areas of MEMS and Microsystems, Mechatronics, and Nonlinear Dynamical Systems and Control. He has been a recipient of 2006 BOYSCAST fellowship of Govt of India, 2007 Best faculty award (ME department) and Prof J.R.Issac fellowship. He has authored several patents and over 85 peer reviewed conference and journal papers. He has coordinated setup of a new laboratory Suman Mashruwala Microengineering Laboratory for research in Microdomain and has successfully developed technologies of Bulk Lithography and Microstereolithography for 3D MEMS fabrication in this laboratory. He has been a qualified teacher of stress relieving, life enhancing techniques of Art of Living foundation by Sri Sri Ravishankar.

Novel Microstereolithography (MSL) and Bulk Lithography (BL) technologies for polymer/ceramic 3D MEMS

Séminaire le 3 Juin 2015, 16h00 à CentraleSupelec (Gif-sur-Yvette) Salle des séminaires du L2S
Prof. Prasanna S. Gandhi


Polymers are increasingly being used for fabrication of MEMS for their advantages of low cost, easy disposability, high flexibility, and so on. With the area of printable organic electronics developing fast there are enormous possibilities with polymer MEMS, especially 3D. This talk will present two indigenously developed technologies for fabrication of polymer 3D MEMS.
The proposed MSL technology has demonstrated resolution of 6micron and a large overall size of fabricated component at the same time: a feature seldom found in other such systems in the literature. The core opto-mechanical scanner (patent pending) and mechatronic system built around it would be presented. This system is demonstrated to have positioning accuracy within 100 nm. Several cases of micro-component fabrication will be demonstrated. Main drawback of MSL is stair-stepping effects on slanted walls. To overcome this limitation, recently "Bulk Lithography" technology has been proposed by our group. The main principle used here is to impose spatial variation of laser energy dose while scanning. The method gives remarkable accuracy in getting free-form surface features desired for microlenses, tapered micro cantilevers, tapered diaphragm micromirrors and so on, which are otherwise not feasible to fabricate. Finally, ceramic microstereolithography and preliminary fabrication of ceramic microcomponents would be demonstrated. The proposed technologies hold potential for direct prototyping and also mass production of MEMS devices along with packaging.

Biography: P.S. Gandhi received the B.Eng. degree in from the University of Bombay, Mumbai in 1994 and the M.Tech degree from the Indian Institute of Technology, Bombay, Mumbai in 1996, both in mechanical engineering. He received the Ph.D. degree in mechanical engineering from the Rice University, Houston in 2001. Since 2001, he has been faculty member, currently Professor, in the Department of Mechanical Engineering at Indian Institute of Technology, Bombay, Mumbai. His research interests are in the areas of MEMS and Microsystems, Mechatronics, and Nonlinear Dynamical Systems and Control. He has been a recipient of 2006 BOYSCAST fellowship of Govt of India, 2007 Best faculty award (ME department) and Prof J.R.Issac fellowship. He has authored several patents and over 85 peer reviewed conference and journal papers. He has coordinated setup of a new laboratory Suman Mashruwala Microengineering Laboratory for research in Microdomain and has successfully developed technologies of Bulk Lithography and Microstereolithography for 3D MEMS fabrication in this laboratory. He has been a qualified teacher of stress relieving, life enhancing techniques of Art of Living foundation by Sri Sri Ravishankar

An introduction to neural fields

Séminaire le 12 Mai 2015, 14h00 à CentraleSupelec (Gif-sur-Yvette) Salle du conseil du L2S - B4.40
Georgios Detorakis, post-doc L2S


The main objective of the field of Computational Neuroscience is to understand how the brain works through mathematical models (numerical and analytical works). Some of these models are described by neural fields equations. Neural fields are integro-differential equations that describe the spatiotemporal dynamics of the activity of a piece of neocortical tissue. Neural fields equations emerge when one assimilates the high number of neurons of the selected piece of brain tissue in its continuum limit. Neural fields have been studied both analytically and numerically by many researchers. They can model many different and interesting biological phenomena such as attention, working memory, self-organization, or synaptic depression. The seminar consists of two parts. The first part is a brief introduction to neuroscience and the second part is dedicated to neural fields. We will review how neural fields equations can be derived, how the steady-state solution can be computed, and its stability can be insured. Finally, some cognitive models that are based on neural fields will be presented.

Bio:
Georgios Detorakis has studied Applied Mathematics and Neuroscience. He did his PhD on cortical plasticity, self-organization and neural fields. During his PhD, he studied the formation of topographic maps in area 3b of the primary somatosensory cortex and the multimodal problem of “Touch and the body”. He is now a postdoc fellow at L2S working with Antoine Chaillet on Parkinson’s disease in the ANR project "SynchNeuro". He uses delayed neural fields in order to model some brain areas that play a crucial role in Parkinson’s disease motor symptoms.

Stability theory, as told by its developers

Séminaire le 5 Mai 2015, 10h00 à CentraleSupelec (Gif-sur-Yvette) Salle du conseil du L2S - B4.40
Antonio Loria, Elena Panteley (L2S)


We present a brief but detailed historical review on the development of stability theory, from its early starts out of the minds of Lagrangia and Dirichlet. The survey carries on to focus on Lyapunov stability. Through exact citations from the works of the developers of stability, including many Soviet texts from the 20th century, we revise the fundamental definitions and theorems; making emphasis on several misfortunate translations which have led to wrong interpretations and ambiguous statements. We favour depth and sacrifice generality: on technical grounds, we focus on the most elementary (yet not so) well-known forms of Lyapunov stability and common but crucial qualifiers that go with it: uniform, asymptotic, global. We revise the origin of the wrongly known invariance principle ...

FREEDM Concept: Power Distribution System Modernization with Solid State Electronics and Integrated Renewables

Séminaire le 5 Mars 2015, 11h00 à CentraleSupelec (Gif-sur-Yvette) Salle des séminaires du L2S
Prof. Iqbal Husain


This FREEDM concept provides an architecture for a future electric power distribution system that is suitable for plug-and-play of distributed renewable energy and distributed energy storage devices. Motivated by the success of the (information) Internet, the FREEDM concept envisions the “Energy Internet,” a system that enables flexible energy sharing for consumers in a residential distribution system. One of the core technologies for the FREEDM system is the solid-state transformer (SST) which is a power electronic device, but makes use of high frequency transformer for isolated AC-AC power conversion. The SST not only dramatically decreases the volume and weight compared with the conventional power transformer, but also behave like a smart transformer with the advantage of power flow control, reactive power compensation capability, and potential fault current limitation. Besides, the regulated low voltage DC/AC bus of SST could be used as an interface to distributed renewable resources and storage devices such as wind, solar, charging stations, and DC micro-grid. The SST is an "Energy Router" proposed to provide such a compatible and flexible interface for energy routing. In addition to the role of a traditional ac transformer, the SST can also provide a low voltage (LV) DC bus. The bi-directional power flow capability of the SST provides possibilities to feed locally generated power back to the grid. Islanding can also be achieved when the HV side is disconnected from grid. The SST has been designed and built based on 13kV SiC MOSFET and JBS diode and is to be connected to medium voltage (MV) distribution network up to 7.2kV and output both a 380V low voltage (LV) dc and 120/240V ac.   

This talk will present the hardware research activities and results aimed at demonstrating the FREEDM concept followed by the power electronic controls for the SST. The experimental results of the developed DC/AC hybrid microgrid built to demonstrate the SST's ability to integrate different renewable energy sources and to improve grid quality will also be discussed.

 
Biography:

Dr. Iqbal Husain is the Director of the Future Renewable Electric Energy Delivery and Management (FREEDM) Engineering Research Center and the ABB Distinguished Professor at North Carolina State University where he joined in Fall 2011. Prior to coming to NC State he was serving as a faculty member at the University of Akron, Ohio for seventeen years. He was a visiting Professor at Oregon State University in 2001, and also lectured at Texas A&M University. Prof. Husain also serves as the Director of the Advanced Transportation Energy Center (ATEC).He received the B.Sc. degree from Bangladesh University of Engineering and Technology, Bangladesh, and the M.S. and Ph.D. degrees from Texas A&M University, College Station, Texas. 

Prof. Husain’s research interests are in the areas of control and modeling of electrical drives, design of electric machines, development of power conditioning circuits, microinverters for distributed power generation, inverter controls for grid synchronization, and modeling and control of electric and hybrid vehicle systems. The primary application of Prof. Husain’s work is in the transportation, automotive, aerospace, power system and renewable energy industries.

Prof. Husain was the General Co-Chair for Energy Conversion Congress & Expo (ECCE) 2012 in Raleigh, NC, the chairman of the IEEE-IAS Transportation Systems Committee, and the chairman of the IEEE-IAS Electric Machines Committee. Prof. Husain received the 2006 SAE Vincent Bendix Automotive Electronics Engineering Award, the 2004 College of Engineering Outstanding Researcher Award, the 2000 IEEE Third Millennium Medal, the 1998 IEEE-IAS Outstanding Young Member award, and several IEEE-IAS prize paper awards. He was elected to be an IEEE Fellow in 2009.

 

 

Online adaptive optimal control of a hybrid electric vehicle

Séminaire le 5 Février 2015, 14h30 à CentraleSupelec (Gif-sur-Yvette) Salle du conseil du L2S - B4.40
Catalin Stefan Teodorescu


Par Doctor Catalin Stefan Teodorescu Project engineer, Flanders' Mechatronics Technology Centre (FMTC), www.fmtc.be A division of Flanders Make, www.flandersmake.be In general, the hybrid driveline concept consists of using simultaneously 2 power sources: the internal combustion engine (ICE) on the one hand, and an electric power source, e.g., a supercapacitor (SC), on the other hand. In the above figure, the red arrows represent power flow of the two illustrated power sources: specifically, it can be generative or regenerative. The latter translates the ability of the SC to store some energy, which can potentially be used in order to achieve significant fuel consumption reduction: e.g. by avoiding wasting energy when the driver pushes the break pedal and instead storing it. In this presentation we will investigate the following problem. In order to be able to cope with the actual demand of the driver expressed in terms of demanded power load (see the above figure), we have an infinite number of choices/combinations concerning the power split ICE versus SC. However, only one (or a few) of these trajectories are optimal in terms of fuel consumption and this is what is being investigated. Two control solutions are presented: Dynamic Programming, mainly used for benchmarking purpose and Equivalent Consumption Minimization Strategy. Results show the latter to be a strong candidate towards online, real-time implementation.

Five generations of sliding mode controllers: stages of evolution

Séminaire le 28 Janvier 2015, 10h00 à CentraleSupelec (Gif-sur-Yvette) Salle du conseil du L2S - B4.40
Prof. Leonid Fridman from Universidad Nacional Autónoma de México (UNAM)


The history and evolution of sliding control will be discussed. The reason for the crisis of the first order sliding modes will be explained. The second order sliding mode control algorithms and their specific features will be presented. The control chattering of the continuous second order super-twisting control algorithm will be discussed. The precision of the arbitrary order sliding mode controllers will be shown. The continuous arbitrary order sliding mode controllers will be presented and discussed. Videos with the experimental illustration of the properties of the main sliding mode algorithms will be presented. Short biography: Leonid M. Fridman received an M.S. degree in mathematics from Kuibyshev (Samara) State University, Samara, Russia, in 1976, a Ph.D. degree in applied mathematics from the Institute of Control Science, Moscow, Russia, in 1988, and a Dr. Sc. degree in control science from Moscow State University of Mathematics and Electronics, Moscow, Russia, in 1998. From 1976 to 1999, he was with the Department of Mathematics, Samara State Architecture and Civil Engineering University. From 2000 to 2002, he was with the Department of Postgraduate Study and Investigations at the Chihuahua Institute of Technology, Chihuahua, Mexico. In 2002, he joined the Department of Control Engineering and Robotics, Division of Electrical Engineering of Engineering Faculty at National Autonomous University of Mexico (UNAM), Mexico. His research interests are variable structure systems. He is currently a Chair of TC on Variable Structure Systems and Sliding mode control of IEEE Control Systems Society. Prof. Fridman is an Associated Editor of the Journal of Franklin Institute, Nonlinear Analysis: Hybrid Systems, and the Conference Editorial Board of IEEE Control Systems Society. He is an author and editor of seven books and 12 special issues and author of more than 350 technical papers on sliding mode control. He is a winner of Scopus prize for the best cited Mexican Scientists in Mathematics and Engineering 2010. He was working as an invited professor in 19 universities and research centers of Argentina, Australia, France, China, Germany, Italy, Israel, and Spain. Web page: verona.fi-p.unam.mx/~lfridman/

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