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Integration of renewable generation into smart grids

Prof. Antonio Gomez-Exposito, Ph.D.
University of Seville, Spain


Renewable energy development and grid integration is a key issue in governmental policies all around the world, owing to its strategic importance in fuel supply diversification and reduction of environmental risks. Within a time framework of less than a decade, electrical energy from renewable sources has become one of the major contributors to the energy mix in several countries, which are closely scrutinized by others with a view to learn the lessons and avoid the pitfalls.

In this tutorial, after reviewing the features and operational constraints of existing power systems, the main concepts, technologies and solutions recently developed to facilitate the integration of relevant amounts of renewable electrical energy will be presented, both at the transmission and distribution levels. The experience accumulated by Spain and other leading countries in renewable energy integration will be summarized.

  • Generalities
    • Review of conventional power systems: components, operation and control
    • HVDC and FACTS devices
    • Renewable sources of electricity generation
  • Integration of bulk renewable generation (transmission levels)
    • Contribution of wind and PV farms to ancillary services (load-frequency & voltage control)
    • Advanced energy management systems
    • Renewable generation forecasting
    • Synchrophasor-based wide-area control
    • Hydro pumped and other energy storage systems
    • Multi-terminal HVDC grids
  • Integration of distributed renewable generation (distribution levels)
    • Mitigation of voltage problems and feeder congestions by DFACTS
    • Demand-side management and self-generation
    • Microgrids and energy aggregators
    • Distributed energy storage & EVs
  • Case Studies: Spain, Germany, Denmark, etc.



Prof. Gomez-Exposito received an Industrial Engineering degree, major in Electrical Engineering, in 1982, and a Doctor Engineering degree in 1985, both with honors from the University of Seville, Spain. Since 1992 he has been a Full Professor at the University of Seville, where he has chaired the Department of Electrical Engineering for almost twelve years. He was also a visiting professor in California and Canada. Currently he is the director of the Endesa Industrial Chair and the Electrical Energy Systems Post-Graduate (M.S. and Ph.D.) Program.

In addition to some 250 technical publications, including almost one hundred papers in high impact journals, Prof. Gomez-Exposito has coauthored a dozen of textbooks and monographs about Circuit Theory and Power System Analysis, among which “Power System State Estimation: Theory and Implementation” (Marcel Dekker, 2004) and “Electric Energy Systems: Analysis and Operation” (CRC Press, 2008), stand out.

He has been principal investigator or participated in nearly 80 research and development projects, both publicly and privately funded. Most of those projects have been developed in close cooperation with the major national and European companies of the electrical sector.

He is a Fellow of the IEEE for his work on power systems analysis and operation, and an IEEE/PES Distinguished Lecturer. He serves on the Editorial Board of the “IEEE Transactions on Power Systems”, “IEEE/PES Letters” and “IEEE Latin America Transactions”, and has also belonged to the scientific or technical committees of the major European conferences related to Power Systems in the last fifteen years.

Among the several professional recognitions he has received, the following recent ones stand out: “Juan López Peñalver” Research and Technology Transfer Award, granted by the Government of Andalucia (2011), “Javier Benjumea” Research Award, granted by Abengoa company (2011), “Fama” Research Award by the University of Seville, and Outstanding Engineer Award, granted by the Spanish Chapter of the IEEE/PES (2010).


Introduction to LED drivers

Prof. Marcos Alonso, Ph.D.
University of Oviedo, Spain


LEDs are becoming an attractive light source owing to their high reliability, long life, high color rendering index and small size. In addition, there are commercially available units that can reach a luminous efficacy as high as 100 lumen/W. These features make LEDs excellent candidates to override fluorescent and other discharge lamps in many applications, including street-lighting, automotive lighting, decorative applications and household appliances. However, power LEDs are still far from being a panacea since they still suffer from several drawbacks. First, due to their nearly constant-voltage behavior, they cannot be supplied from the dc or ac voltage source directly. Therefore, some kind of current-limiting device must be used, similarly to the ballast used to limit the current through a discharge lamp. On the other hand, the high efficacy of power LEDs is only maintained under tight operating conditions, which include low direct current and low junction temperature. This tutorial will deal with topics related to LED driving, including: introduction to lighting and vision, color theory, color mixing, LED behavior and modeling, thermal management, dimming, DC-supplied LED drivers and off-line LED drivers.


J. Marcos Alonso (S’94, M’98, SM’03) received the M.Sc. Degree and Ph.D. both in electrical engineering from the University of Oviedo, Spain, in 1990 and 1994 respectively. Since 2007, he has been appointed as full Professor at the Electrical Engineering Department of the University of Oviedo.

Prof. Alonso is co-author of more than three hundred journal and conference publications. His research interests include electronic ballasts, LED power supplies, power factor correction and switching converters in general. He was supervisor of eight Ph.D. Thesis and he is the holder of seven Spanish patents.

Prof. Alonso has been awarded with the Early Career Award of the IEEE Industrial Electronics Society in 2006. He was honoured with the University of Oviedo Electrical Engineering Doctorate Award for 1996. He also holds three IEEE paper awards. Since October 2002 he serves as an Associate Editor of the IEEE Transactions on Power Electronics. He has been Co-Guest Editor of two special issues in lighting applications published in the IEEE Transactions on Power Electronics (2007) and IEEE Transactions on Industrial Electronics (2012) and has co-organized several conference special sessions. Since October 2012, he also serves as secretary of the IEEE IAS Industrial Lighting and Display Committee (ILDC). He has been elected as Member-at-Large of the IEEE IAS Executive Board for the term 2013-2014. He is also member of the European Power Electronics Association and he belongs to the International Steering Committee of the European Conference on Power Electronics and Applications (EPE), where he has collaborated as topic co-chair since 2007.


Performance enhancement in diesel-hybrid autonomous power systems (mini-grids)

Prof. Luiz Antonio Correa Lopes, Ph.D.
Concordia University, Canada


Traditionally, remote communities worldwide consist of autonomous power systems (mini-grids) supplied by diesel power plants with two or more diesel engine generator sets (gensets) for increased reliability. This is a mature technology, but the optimization of the operation of the system for reduced fuel consumption and maintenance costs is not an easy task. Remote communities are characterized by highly variable load profiles, forcing the diesel power plants to operate with large spinning reserves, high unit cycling and low efficiency. While the integration of renewable energy sources (RESs) offers good potential for reducing fuel consumption, it further complicates the dispatching of the gensets, due to its fluctuating characteristics. This seminar discusses a number of approaches that can enhance the performance of the system not only in terms of fuel consumption but also regarding power quality and reliability. Medium-size energy storage systems (ESSs) can be used for supporting the diesel power plant, balancing the load and bringing the gensets to operating points of higher efficiency, as well as for forming the grid, allowing the gensets to be shut-down when the conditions are adequate. Conversely, small short-term BESs can be used as a virtual synchronous machine (VSMs), emulating inertia and damping, for enhancing frequency stability in systems with high penetration of inertia-less RES such as PV. Many remote communities present secondary loads such as water heaters and ice making plants that can be employed for power balancing and energy management. Techniques that are suitable for systems that operate with variable frequency so that decentralized loads and RESs can assist with power balancing without dedicated communication channels, by using appropriate active power (P) vs. frequency (f) droop characteristics will be discussed. In this context, a power dispatch technique that includes frequency setting so as to control the power demand of controllable loads is proposed. Case studies based on MATLAB-Simulink with the description of the various control loops will be presented.


Luiz A. C. Lopes was born in Belém, Brazil, in 1965. He obtained his M.Sc. degree from Federal University of Santa Catarina (UFSC, Brazil) and the Ph.D. degree from McGill University in 1989 and 1996, respectively. He was an Assistant Professor at Federal University of Pará (UFPA), Brazil, from 1989-1991 and an Associate Professor from 1996-2001. He joined the Department of Electrical and Computer Engineering in 2002 at the rank of Associate Professor. His present research interests are renewable energy systems and power electronic converters for distributed power generation. Dr. has supervised/co-supervised to completion 6 Ph.D. and 20 M.Sc. students. He has 28 journal papers published and accepted for publication as well as 65 conference papers. Dr. Lopes has been actively attracting external funds for supporting his research work, from NSERC to national institutes such as CanmetENERGY (Varennes) and various companies including Bombardier, ALCOA, TM4 and GDS. He was a technical representative for Canada in Task 11 “PV Hybrid Systems within Mini-grids” of the International Energy Agency, Photovoltaic Power Systems Programme (IEA-PVPS), and the lead author of Report T11-07:2012 “PV Hybrid Mini-grids: Applicable control Methods for Various Situations.” He has been a member of the CSC/IEC/TC82 of the Canadian National Committee on the International Electrotechnical Committee since August 2006. Dr. Lopes is a senior member of the IEEE and a member of the Ordre des Ingénieurs du Québec (OIQ).


Power Electronics for distributed power systems: state of the art and future trends

Prof. Jose Antenor Pomilio, Ph.D.
University of Campinas, Brazil


Power electronic converters are indispensable in the context of distributed generation and smart grid to the best use of most renewable energy sources. The presence of different sources and converters topologies, as well as the diversity of control and command strategies, opens exciting new lines of research and technological development. This tutorial intends to make a discussion of the different sources of energy, especially the renewable ones, and as the power electronic converters perform the interface among sources, loads and networks. Also, it will discuss issues related to power quality problems associated with typical applications in distribution networks.


José Antenor Pomilio received the B.S., M.S., and Ph.D. degrees in electrical engineering from the University of Campinas, Campinas, Brazil, in 1983, 1986, and 1991, respectively. From 1988 to 1991, he was the Head of the Power Electronics Group, Brazilian Synchrotron Light Laboratory. He was a Visiting Professor with the University of Padova, Padova, Italy, in 1993, and with the University of Rome III, Rome, Italy, in 2003. He is a Professor with the School of Electrical and Computer Engineering, University of Campinas, where he has been teaching since 1984. His main research interests are switching-mode power supplies, power-factor correction, and active power filters. Dr. Pomilio was the President of the Brazilian Power Electronics Society in 2000–2002 and a member of the Administrative Committee of the IEEE Power Electronics Society in 1997-2002.


The modular multilevel converter and other multilevel topologies

Prof. Josep Pou, Ph.D.
Technical University of Catalonia, Spain, and University of New South Wales, Australia

Prof. Jordi Zaragoza, Ph.D.
Technical University of Catalonia, Spain


A comprehensive analysis of various multilevel converter topologies will be presented in the first part of the tutorial. The operating principle of these converters, modulation techniques, and control schemes will be analyzed. The second part will be focused on the modular multilevel converter (MMC), which is the most promising topology for the future high-voltage direct current (HVDC) transmission systems. It will include MMC fundamentals, modeling, modulation strategies, capacitor voltage balance, and circulating current control.


Josep Pou received the B.S., M.S., and Ph.D. degrees in electrical engineering from the Technical University of Catalonia (UPC), Catalonia, Spain, in 1989, 1996, and 2002, respectively.

During 1989, he was the Technical Director of Polylux S.A. In 1990, he joined the faculty of UPC as an Assistant Professor, where he became an Associate Professor in 1993. Since February 2013, he is a Professor with the University of New South Wales (UNSW), Sydney, while he keeps a permanent position at UPC. From February 2001 to January 2002, and February 2005 to January 2006, he was a Researcher at the Center for Power Electronics Systems, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg. From January 2012 to January 2013, he was a Researcher at the Australian Energy Research Institute (AERI), UNSW, Sydney. Since 2006, he collaborates as a research consultant for TECNALIA. He has authored more than 150 published technical papers and has been involved in several industrial projects and educational programs in the fields of power electronics and systems. His research interests include modeling and control of power converters, multilevel converters, power quality, renewable energy generation, and HVDC transmission systems.


Jordi Zaragoza received the B.S. degree in electronic engineering, the M.S. degree in automatic and electronic industrial engineering and Ph.D. degree from the Technical University of Catalonia (UPC), Catalonia, Spain, in 2001, 2004, and 2011 respectively.

In 2003, he joined the faculty of UPC as an Assistant Professor, where he became an Associate Professor in 2012. From September 2006 to September 2007 he was a researcher at the Energy Unit of ROBOTIKER-TECNALIA Technologic Corporation, Basque Country, Spain. He is the author of more than 50 published technical papers and has been involved in several projects in the fields of power electronics and systems. His research interests include modeling and control of power converters, multilevel converters, wind energy, power quality and HVDC transmission systems.

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