Microgrids E-Book

• Herausgeber: John Wiley & Sons
• Kategorie: Wissenschaft und neue Technologien
• Serie: Wiley - IEEE
• Sprache: Englisch

Seitenzahl: 501

Veröffentlichungsjahr: 2013

Beschreibung

Microgrids are the most innovative area in the electric power industry today. Future microgrids could exist as energy-balanced cells within existing power distribution grids or stand-alone power networks within small communities.

A definitive presentation on all aspects of microgrids, this text examines the operation of microgrids – their control concepts and advanced architectures including multi-microgrids. It takes a logical approach to overview the purpose and the technical aspects of microgrids, discussing the social, economic and environmental benefits to power system operation. The book also presents microgrid design and control issues, including protection and explaining how to implement centralized and decentralized control strategies.

Key features:

• original, state-of-the-art research material written by internationally respected contributors 
• unique case studies demonstrating success stories from real-world pilot sites from Europe, the Americas, Japan and China
• examines market and regulatory settings for microgrids, and provides evaluation results under standard test conditions
• a look to the future – technical solutions to maximize the value of distributed energy along with the principles and criteria for developing commercial and regulatory frameworks for microgrids

Offering broad yet balanced coverage, this volume is an entry point to this very topical area of power delivery for electric power engineers familiar with medium and low voltage distribution systems, utility operators in microgrids, power systems researchers and academics. It is also a useful reference for system planners and operators, manufacturers and network operators, government regulators, and postgraduate power systems students.

CONTRIBUTORS

Thomas Degner
Aris Dimeas
Alfred Engler
Nuno Gil
Asier Gil de Muro
Guillermo Jiménez-Estévez
George Kariniotakis
George Korres
André Madureira
Meiqin Mao
Chris Marnay
Jose Miguel Yarza
Satoshi Morozumi
Alexander Oudalov
Frank van Overbeeke
Rodrigo Palma Behnke
Joao Abel Pecas Lopes
Fernanda Resende
John Romankiewicz
Christine Schwaegerl
Nikos Soultanis
Liang Tao
Antonis Tsikalakis

Leseprobe

Contents

Cover

Title Page

Copyright

Dedication

Foreword

Preface

List of Contributors

Chapter 1: The Microgrids Concept

1.1 Introduction

1.2 The Microgrid Concept as a Means to Integrate Distributed Generation

1.3 Clarification of the Microgrid Concept

1.4 Operation and Control of Microgrids

1.5 Market Models for Microgrids

1.6 Status Quo and Outlook of Microgrid Applications

References

Chapter 2: Microgrids Control Issues

2.1 Introduction

2.2 Control Functions

2.3 The Role of Information and Communication Technology

2.4 Microgrid Control Architecture

2.5 Centralized and Decentralized Control

2.6 Forecasting

2.7 Centralized Control

2.8 Decentralized Control

2.9 State Estimation

2.10 Conclusions

Appendix 2.A Study Case Microgrid

References

Chapter 3: Intelligent Local Controllers

3.1 Introduction

3.2 Inverter Control Issues in the Formation of Microgrids

3.3 Control Strategies for Multiple Inverters

3.4 Implications of Line Parameters on Frequency and Voltage Droop Concepts

3.5 Development and Evaluation of Innovative Local Controls to Improve Stability

3.6 Conclusions

References

Chapter 4: Microgrid Protection

4.1 Introduction

4.2 Challenges for Microgrid Protection

4.3 Adaptive Protection for Microgrids

4.4 Fault Current Source for Effective Protection in Islanded Operation

4.5 Fault Current Limitation in Microgrids

4.6 Conclusions

Appendices:

References

Chapter 5: Operation of Multi-Microgrids

5.1 Introduction

5.2 Multi-Microgrid Control and Management Architecture

5.3 Coordinated Voltage/var Support

5.4 Coordinated Frequency Control

5.5 Emergency Functions (Black Start)

5.6 Dynamic Equivalents

5.7 Conclusions

References

Chapter 6: Pilot Sites: Success Stories and Learnt Lessons

6.1 Introduction

6.2 Overview of Microgrid Projects in Europe

References

6.3 Overview of Microgrid Projects in the USA

References

6.4 Overview of Japanese Microgrid Projects

6.5 Overview of Microgrid Projects in China

References

6.6 An Off-Grid Microgrid in Chile

References

Chapter 7: Quantification of Technical, Economic, Environmental and Social Benefits of Microgrid Operation

7.1 Introduction and Overview of Potential Microgrid Benefits

7.2 Setup of Benefit Quantification Study

7.3 Quantification of Microgrids Benefits under Standard Test Conditions

7.4 Impact of External Market Prices and Pricing Policies

7.5 Impact of Microgrid Operation Strategy

7.6 Extension to European Scale

7.7 Conclusions

References

Index

This edition first published 2014

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Library of Congress Cataloging-in-Publication Data

Microgrid: architectures and control / edited by professor Nikos

Hatziargyriou.

1 online resource.

Includes bibliographical references and index.

Description based on print version record and CIP data provided by

publisher; resource not viewed.

ISBN 978-1-118-72064-6 (ePub) – ISBN 978-1-118-72065-3 – ISBN 978-1-118-72068-4 (cloth)

1. Smart power grids. 2. Small power production

facilities. I. Hatziargyriou, Nikos, editor of compilation.

TK3105

621.31–dc23

2013025351

A catalogue record for this book is available from the British Library.

ISBN: 978-1-118-72068-4

Dedicated to the Muse of Creativity

Foreword

The idea of microgrids is not new. However, as new technologies are coming into existence to harvest renewable energy as well as more efficient electricity production methods coupled with the flexibility of power electronics; a new industry is developing to promote these technologies and organize them into microgrids for extracting the maximum benefits for owners and the power grid. More than 15 years ago, the Department of Energy has sponsored early research that laid the foundations for microgrids and explored the benefits. One key aspect is the ability and promise to address environmental concerns that have been growing in recent years. Today the microgrid concept has exploded to include a variety of architectures of energy resources into a coordinated energy entity that its value is much greater than the individual components. As a result the complexity of microgrids has increased. It is in this environment of evolution of microgrids that the present book is very welcome. It is written in a way that provides valuable information for specialist as well as non-specialists.

Chapter 1 provides a well thought view of the microgrid concept from the various forms of implementation to the potential economic, environmental and technical benefits. It identifies the role of microgrids in altering the distribution system as we know it today and at the same time elaborates on the formation of microgrids as an organized entity interfaced to distribution systems. In a refreshingly simple way identifies the enabling technologies for microgrids, that is power electronics, communications, renewable resources. It discusses in simple terms the ability of microgrids to minimize green house gases, help the power grid with load balancing and voltage control and assist power markets. While it is recognized that participation of the microgrids in power markets is limited by their size, it discusses possible ways that microgrids can market their assets via aggregators and opens the field for other innovations.

The book addresses two of the great challenges of microgrids: control and protection. Four chapters are devoted to these complex problems, three on control (Chapters 2, 3 and 5) and one on protection (Chapter 4). The multiplicity of control issues and their complexity is elaborated in a clear and concise manner. Since microgrids comprise many resources that are interfaced via power electronics, the book presents the organization of the control problems in a hierarchical architecture that consists of local controllers that control specific resources, their operation and their protection as well as outer loop controllers that perform load-generation management, islanding operation as well as the interaction with up-stream controllers including power system control centers. It provides a good overview of approaches as well as the role of state estimation in controlling and operating a microgrid. In addition to conventional control methods, recent intelligent control approaches are also discussed. The specific issues and challenges of microgrid control are clearly elaborated. As an example, because the microgrid typically comprises many inverters connecting various resources to the microgrid it is possible to trigger oscillations due to inverter control interactions. Methods for solving these issues are clearly discussed in an easy to follow way. It is recognized that multiple microgrids can exist in a system and the issue of controlling and coordinating all the microgrids is very important from the point of view of managing the microsources as well as providing services to the power grid by coordinating all the resources. The services can be any of the ancillary services that are typically provided by large systems: frequency control, voltage control, power balance, capacity reserves. The hierarchies involved in the control and operation of multi-microgrid systems is eloquently presented as a hierarchical control problem.

Protection of microgrids is a challenging problem due to the fact that microgrid resources provide limited fault currents. Detection of faults in microgrids is problematic at best because the grid side fault current contribution may be very high while the contribution from microsources is limited. Present protection schemes and functions are not reliable for microgrids. The book describes clever methods for providing adequate protection functions such as adaptive protection schemes, addition of components that will provide temporarily high fault currents to enable the operation of protective relays, increasing inverter capacity and therefore fault current contribution. While the book provides some solutions it also makes it clear that there is much more work that needs to be done to reliably protect microgrids.

The basic approaches in designing, controlling and protecting microgrids are nicely complimented by a long list of microgrid projects around the globe that provide a picture of the evolution of microgrid design and lessons learned. Specific microgrid projects in Europe, United States, Japan, China and Chile are described and discussed. These projects provide an amazing insight into the lessons learned, challenges faced and issues resolved and issues outstanding. The examples span small capacity microgrids as well as some very large microgrids; grid-connected microgrids as well as stand-alone or island microgrids. The information provided is extremely useful and enables appreciation of the challenges as well as the rewards of these systems.

Finally, the last chapter elaborates on the technical, economic, environmental and social benefits of microgrids. The discussion is qualitative as well as quantitative. While the quantitative analysis is very much dependent upon specific areas and other conditions, the qualitative discussion is applicable to microgrids anywhere in the globe. Indirectly, this discussion makes the case for microgrids comprising mostly renewable energy resources as a big component in solving the environmental, economic and social issues that are facing a society that relies more and more in electric energy. The technical issues are solvable for transforming distribution systems into a distributed microgrid. The work presented in this book will be a fundamental reference toward the promotion and proliferation of microgrids and the accompanied deployment of renewable resources.

This book is a must read resource for anyone interested in the design and operation of microgrids and the integration of renewable resources into the power grid.

Sakis Meliopoulos

Georgia Power Distinguished Professor

School of Electrical and Computer Engineering

Georgia Institute of Technology

Atlanta, Georgia

Preface

The book deals with understanding, analyzing and justifying Microgrids, as novel distribution network structures that unlock the full potential of Distributed Energy Resources (DER) and thus form building blocks of future Smartgrids. In the context of this book, Microgrids are defined as distribution systems with distributed energy sources, storage devices and controllable loads, operated connected to the main power network or islanded, in a controlled, coordinated way. Coordination and control of DER is the key feature that distinguishes Microgrids from simple distribution feeders with DER. In particular, effective energy management within Microgrids is the key to achieving vital efficiency benefits by optimizing production and consumption of energy. Nevertheless, the technical challenges associated with the design, operation and control of Microgrids are immense. Equally important is the economic justification of Microgrids considering current electricity market environments and the quantified assessment of their benefits from the view of the various stakeholders involved.

Discussions about Microgrids started in the early 2000, although their benefits for island and remote, off-grid systems were already generally appreciated. Nowadays, Microgrids are proposed as vital solutions for critical infrastructures, campuses, remote communities, military applications, utilities and communal networks. Bright prospects for a steady market growth are foreseen. The book is intended to meet the needs of practicing engineers, familiar with medium- and low-voltage distribution systems, utility operators, power systems researchers and academics. It can also serve as a useful reference for system planners and operators, technology providers, manufacturers and network operators, government regulators, and postgraduate power systems students.

The text presents results from a 6-year joint European collaborative work conducted in the framework of two EC-funded research projects. These are the projects “Microgrids: Large Scale Integration of Micro-Generation to Low Voltage Grids,” funded within the 5th Framework programme (1998–2002) and the follow-up project “More Microgrids, Advanced Architectures and Control Concepts for More Microgrids” funded within the 6th Framework Programme (2002–2006). The consortia involved were coordinated by the editor of this book and comprised a number of industrial partners, power utilities and academic research teams from 12 EU countries. A wealth of information and many practical conclusions were derived from these two major research efforts. The book attempts to clarify the role of Microgrids within the overall power system structure and focuses on the main findings related to primary and secondary control and management at the Microgrid and Multi-Microgrid level. It also provides results from quantified assessment of the Microgrids benefits from an economical, environmental, operational and social point of view. A separate chapter beyond the EC projects, provided by a more international authorship is devoted to an overview of real-world Microgrids from various parts of the world, including, next to Europe, United States of America, Japan, China and Chile.

Chapter 1, entitled “The Microgrids Concept,” co-authored by Christine Schwaegerl and Liang Tao, clarifies the key features of Microgrids and underlines the distinguishing characteristics from other DG dominated structures, such as Virtual Power Plants. It discusses the main features related to their operation and control, the market models and the effect of possible regulatory settings and provides an exemplary roadmap for Microgrid development in Europe.

Chapter 2, entitled “Microgrids Control Issues” co-authored by Aris Dimeas, Antonis Tsikalakis, George Kariniotakis and George Korres, deals with one of the key features of Microgrids, namely their energy management. It presents the hierarchical control levels distinguished in Microgrids operation and discusses the principles and main functions of centralized and decentralized control, including forecasting and state estimation. Next, centralized control functions are analyzed and illustrated by a practical numerical example. Finally, an overview of the basic multi-agent systems concepts and their application for decentralized control of Microgrids is provided.

Chapter 3, entitled “Intelligent Local Controllers,” co-authored by Thomas Degner, Nikos Soultanis, Alfred Engler and Asier Gil de Muro, presents primary control capabilities of DER controllers. The provision of ancillary services in interconnected mode and the capabilities of voltage and frequency control, in case of islanded operation and during transition between the two modes are outlined. Emphasis is placed on the implications of the high resistance over reactance ratios, typically found in LV Microgrids. A control algorithm based on the fictitious impedance method to overcome the related problems together with characteristic simulation results are provided.

Chapter 4, entitled “Microgrid Protection,” co-authored by Alexander Oudalov, Thomas Degner, Frank van Overbeeke and Jose Miguel Yarza, deals with methods for effective protection in Microgrids. A number of challenges are caused by DER varying operating conditions, the reduced fault contribution by power electronics interfaced DER and the occasionally increased fault levels. Two adaptive protection techniques, based on pre-calculated and on-line calculated settings are proposed including practical implementation issues. Techniques to increase the amount of fault current level by a dedicated device and the possible use of fault current limitation are also discussed.

Chapter 5, entitled “Operation of Multi-Microgrids,” co-authored by João Abel Peças Lopes, André Madureira, Nuno Gil and Fernanda Resende examines the operation of distribution networks with increasing penetration of several low voltage Microgrids, coordinated with generators and flexible loads connected at medium voltage. An hierarchical management architecture is proposed and functions for coordinated voltage/VAR control and coordinated frequency control are analyzed and simulated using realistic distribution networks. The capability of Microgrids to provide black start services are used to provide restoration guidelines. Finally, methods for deriving Microgrids equivalents for dynamic studies are discussed.

Chapter 6, entitled “Pilot Sites: Success Stories and Learnt Lessons” provides an overview of real-world Microgrids, already in operation as off-grid applications, pilot cases or full-scale demonstrations. The material is organized according to geographical divisions. George Kariniotakis, Aris Dimeas and Frank van Overbeeke describe three pilot sites in Europe developed within the more Microgrids project; John Romankiewicz and Chris Marnay provide an overview of Microgrid Projects in the United States; Satoshi Morozumi provide an overview of the Japanese Microgrid Projects; Meiqin Mao describes the Microgrid Projects in China and Rodrigo Palma Behnke and Guillermo Jiménez-Estévez provide details of an off-grid Microgrid in Chile. These projects are of course indicative of a continuously growing list, they provide, however, a good impression of the on-going developments in the field.

Chapter 7, entitled “Quantification of Technical, Economic, Environmental and Social Benefits of Microgrid Operation,” co-authored by Christine Schwaegerl and Liang Tao attempts to quantify the Microgrids benefits using typical European distribution networks of different types and assuming various DER penetration scenarios, market conditions, prices and costs developments for the years 2020, 2030 and 2040. Sensitivity analysis of the calculated benefits is performed. Although, the precision of these quantified benefits is subject to the high uncertainties in the underlying assumptions, the positive effects of Microgrids operation can be safely observed in all cases.

Next to the co-authors of the various chapters, there are many researchers who have contributed to the material of this book by their knowledge, research efforts and fruitful collaboration during the numerous technical meetings of the Microgrids projects. I am indebted to all of them, but I feel obliged to refer to some names individually and apologize in advance for the names I might forget. I would like to start with Profs. Nick Jenkins and Goran Strbac from UK; I have benefited tremendously while working with them and their insights and discussions helped clarify many concepts discussed in the book. I am indebted to Britta Buchholz, Christian Hardt, Roland Pickhan, Mariam Khattabi, Michel Vandenbergh, Martin Braun, Dominik Geibel and Boris Valov from Germany; Mikes Barnes, Olimpo Anaya-Lara, Janaka Ekanayake, Pierluigi Mancarella, Danny Pudjianto and Tony Lakin from UK; Jose Maria Oyarzabal, Joseba Jimeno and Iñigo Cobelo from Spain; Nuno Melo and António Amorim from Portugal; Sjef Cobben from the Netherlands; John Eli Nielsen from Denmark; Perego Omar and Michelangeli Chiara from Italy; Aleksandra Krkoleva, Natasa Markovska and Ivan Kungulovski from FYR of Macedonia; Grzegorz Jagoda and Jerszy Zielinski from Poland; my NTUA colleagues Stavros Papathanassiou and Evangelos Dialynas; and Stathis Tselepis, Kostas Elmasides, Fotis Psomadellis, Iliana Papadogoula, Manolis Voumvoulakis, Anestis Anastasiadis, Fotis Kanellos, Spyros Chadjivassiliadis and Maria Lorentzou from Greece. I express my gratitude to my PhD students and collaborators Georgia Asimakopoulou, John Karakitsios, Evangelos Karfopoulos, Vassilis Kleftakis, Panos Kotsampopoulos, Despina Koukoula, Jason Kouveliotis-Lysicatos, Alexandros Rigas, Nassos Vassilakis, Panayiotis Moutis, Christina Papadimitriou and Dimitris Trakas, who reviewed various chapters of the book and provided valuable comments. Finally, I wish to thank the EC DG Research&Innovation for providing the much appreciated funding for the research leading to this book, especially the Officers Manuel Sanchez Jimenez and Patrick Van Hove.

Nikos Hatziargyriou

List of Contributors

Thomas Degner, Thomas Degner is Head of Department Network Technology and Integration at Fraunhofer IWES, Kassel, Germany. He received his Diploma in Physics and his Ph.D. from University of Oldenburg. His particular interests include microgrids, interconnection requirements and testing procedures for distributed generators, as well as power system stability and control for island and interconnected power systems with a large share of renewable generation.

Aris Dimeas, Aris L. Dimeas received the Diploma and his Ph.D. in Electrical and Computer Engineering from the National Technical University of Athens (NTUA). He is currently senior researcher at the Electrical and Computer Engineering School of NTUA. His research interests include dispersed generation, artificial intelligence techniques in power systems and computer applications in liberalized energy markets.

Alfred Engler, Alfred Engler received his Dipl.-Ing. (Master's) from the Technical University of Braunschweig and the degree Dr.-Ing. (Ph.D.) from the University of Kassel. He has been head of the group Electricity Grids and of Power Electronics at ISET e.V. involved with inverter control, island grids, microgrids, power quality and grid integration of wind power. He is currently Manager of the Department of Advance Development at Liebherr Elektronik GmbH.

Nuno Gil, Nuno José Gil received his electrical engineering degree from the University of Coimbra and M.Sc. and Ph.D. from the University of Porto. He is a researcher in the Power Systems Unit of INESC Porto and assistant professor at the Polytechnic Institute of Leiria, Portugal. His research interests include integration of distributed generation and storage devices in distribution grids, islanded operation and frequency control.

Guillermo Jiménez-Estévez, Guillermo A. Jiménez-Estévez received the B.Sc. degree in Electrical Engineering from the Escuela Colombiana de Ingeniería, Bogotá, and the M.Sc. and Ph.D. degrees from the University of Chile, Santiago. He is assistant director of the Energy Center, FCFM, University of Chile.

George Kariniotakis, Georges Kariniotakis received his engineering and M.Sc. degrees from the Technical University of Crete, Greece and his Ph.D. degree from Ecole des Mines de Paris. He is currently with the Centre for Processes, Renewable Energies & Energy Systems (PERSEE) of MINES ParisTech as senior scientist and head of the Renewable Energies & Smartgrids Group. His research interests include renewables, forecasting and smartgrids.

George Korres, George N. Korres received the Diploma and Ph.D. degrees in Electrical and Computer Engineering from the National Technical University of Athens. He is professor with the School of Electrical and Computer Engineering of NTUA. His research interests are in power system state estimation, power system protection and industrial automation.

André Madureira, André G. Madureira received an Electrical Engineering degree, M.Sc. and Ph.D. from the Faculty of Engineering of the University of Porto. He is senior researcher/consultant in the Power Systems Unit of INESC Porto. His research interests include integration of distributed generation and microgeneration in distribution grids, voltage and frequency control and smartgrid deployment.

Meiqin Mao, Meiqin Mao is professor with Research Center of Photovoltaic System Engineering, Ministry of Education, Hefei University of Technology, P.R. China. She has been devoted to renewable energy generation research since 1993. Her research interests include optimal operation and energy management of microgrids and power electronics applications in renewable energy systems.

Chris Marnay, Chris Marnay has been involved in microgrid research since the 1990s. He studies the economic and environmental optimization of microgrid equipment selection and operation. He has chaired nine of the annual international microgrid symposiums.

Satoshi Morozumi, Satoshi Morozumi has graduated from a doctor course in Hokkaido University. He joined Mitsubishi Research Institute, Inc. and for past 20 years, he was engaged in the utility's system. He is currently director general of Smart Community Department at NEDO, where he is in charge of management of international smart community demonstrations.

Asier Gil de Muro, Asier Gil de Muro has received his M.Sc. in Electrical Engineering from the School of Engineering of the University of the Basque Country in Bilbao, Spain. Since 1999 he is researcher and project manager at the Energy Unit of TECNALIA, working in projects dealing with power electronics equipment, design and developing of grid interconnected power devices, microgrids and active distribution.

Alexandre Oudalov, Alexandre Oudalov received the Ph.D. in Electrical Engineering in 2003 from the Swiss Federal Institute of Technology in Lausanne (EPFL), Switzerland. He joined ABB Switzerland Ltd., Corporate Research Center in 2004 where he is currently a principal scientist in the Utility Solutions group. His research interests include T&D grid automation, integration and management of DER and control and protection of microgrids

Frank van Overbeeke, Frank van Overbeeke graduated in Electrical Power Engineering at Delft University of Technology and obtained a Ph.D. in Applied Physics from the University of Twente. He is founder and owner of EMforce, a consultancy firm specialized in power electronic applications for distribution networks. He has acted as the system architect for several major utility energy storage projects in the Netherlands.

Rodrigo Palma Behnke, Rodrigo Palma Behnke received his B.Sc. and M.Sc. on Electrical Engineering from the Pontificia Universidad Católica de Chile and a Dr.-Ing. from the University of Dortmund, Germany. He is the director of the Energy Center, FCFM, and the Solar Energy Research Center SERC-Chile, he also is associate professor at the Electrical Engineering Department, University of Chile.

João Abel Peças Lopes, João Abel Peças Lopes is full professor at Faculty of Engineering of University of Porto and member of the Board of Directors of INESC Porto

Fernanda Resende, Fernanda O. Resende received an Electrical Engineering degree, from the University of Trás-os-Montes e Alto Douro and M.Sc. and Ph.D. from the Faculty of Engineering of the University of Porto. She is senior researcher in the Power Systems Unit of INESC Porto and assistant professor at Losófona University of Porto. Her research interests include integration of distributed generation, modeling and control of power systems and small signal stability.

John Romankiewicz, John Romankiewicz is a senior research associate at Berkeley Lab, focusing on distributed generation and energy efficiency policy. He has been working in the energy sector in the United States and China for the past 7 years and is currently studying for his Masters of Energy and Resources and Masters of Public Policy at UC Berkeley.

Christine Schwaegerl, Christine Schwaegerl received her Diploma in Electrical Engineering at the University of Erlangen and her Ph.D. from Dresden Technical University, Germany. In 2000, she joined Siemens AG where she has been responsible for several national and international research and development activities on power transmission and distribution networks. Since 2011 she is professor at Augsburg University of Applied Science.

Nikos Soultanis, Nikos Soultanis graduated from the Electrical Engineering Department of the National Technical University of Athens (NTUA) in 1989 and has worked on various projects as an independent consultant. He received his M.Sc. from the University of Manchester Institute of Science and Technology (UMIST) and his Ph.D. from NTUA. He works currently in the dispatching center of the Greek TSO and as an associated researcher at NTUA with interests in the area of distributed generation applications and power system analysis.

Liang Tao, Liang Tao is a technical consultant working at Siemens PTI, Germany. His main research interests include stochastic modeling of renewable energy sources, dimensioning and operation methods for storage devices, optimal power flow and optimal scheduling of multiple types of resources in smartgrids.

Antonis Tsikalakis, Antonis G. Tsikalakis received the Diploma and Ph.D. degrees in electrical and computer engineering from NTUA. Currently he is an adjunct lecturer in the School of Electronics and Computer Engineering of the Technical University of Crete (TUC) and research associate of the Technological Educational Institute of Crete. He co-operates with the NTUA as post-doc researcher. His research interests are in distributed generation, energy storage and autonomous power systems operation with increased RES penetration.

José Miguel Yarza, José Miguel Yarza received an M.S. degree in Electrical Engineering and a master degree on “Quality and Security in Electrical Energy Delivery. Power System Protections” from the University of Basque Country and an executive MBA from ESEUNE Business School. He is currently CTO at CG Automation. He is member of AENOR SC57 (Spanish standardization body), IEC TC57 and CIGRE.

1

The Microgrids Concept

Christine Schwaegerl and Liang Tao

1.1 Introduction

Modern society depends critically on a secure supply of energy. Growing concerns for primary energy availability and aging infrastructure of current electrical transmission and distribution networks are increasingly challenging security, reliability and quality of power supply. Very significant amounts of investment will be required to develop and renew these infrastructures, while the most efficient way to meet social demands is to incorporate innovative solutions, technologies and grid architectures. According to the International Energy Agency, global investments required in the energy sector over the period 2003–2030 are estimated at $16 trillion.

Future electricity grids have to cope with changes in technology, in the values of society, in the environment and in economy [1]. Thus, system security, operation safety, environmental protection, power quality, cost of supply and energy efficiency need to be examined in new ways in response to changing requirements in a liberalized market environment. Technologies should also demonstrate reliability, sustainability and cost effectiveness. The notion of smart grids refers to the evolution of electricity grids. According to the European Technology Platform of Smart Grids [2], a smart grid is an electricity network that can intelligently integrate the actions of all users connected to it – generators, consumers and those that assume both roles – in order to efficiently deliver sustainable, economic and secure electricity supplies. A smart grid employs innovative products and services together with intelligent monitoring, control, communication and self-healing technologies.