Electromagnetic Time Reversal E-Book

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

Seitenzahl: 378

Veröffentlichungsjahr: 2017

Beschreibung

The aim of this book is to familiarize the reader with the concept of electromagnetic time reversal, and introduce up-to-date applications of the concept found in the areas of electromagnetic compatibility and power systems. It is original in its approach to describing propagation and transient issues in power networks and power line communication, and is the result of the three main editors' pioneering research in the area.

Leseprobe

Electromagnetic Time Reversal

Application to Electromagnetic Compatibility and Power Systems

Edited by

Farhad Rachidi

Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland

Marcos Rubinstein

University of Applied Sciences ofWestern Switzerland, Yverdon, Switzerland

Mario Paolone

Swiss Federal Institute of Technology (EPFL), Lausanne, Switzerland

This edition first published 2017

© 2017 John Wiley & Sons, Ltd

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The right of Farhad Rachidi, Marcos Rubinstein, and Mario Paolone to be identified as the authors of the editorial material in this work has been asserted in accordance with law.

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The publisher and the authors make no representations or warranties with respect to the accuracy or completeness of the contents of this work and specifically disclaim all warranties, including without limitation any implied warranties of fitness for a particular purpose. This work is sold with the understanding that the publisher is not engaged in rendering professional services. The advice and strategies contained herein may not be suitable for every situation. In view of ongoing research, equipment modifications, changes in governmental regulations, and the constant flow of information relating to the use of experimental reagents, equipment, and devices, the reader is urged to review and evaluate the information provided in the package insert or instructions for each chemical, piece of equipment, reagent, or device for, among other things, any changes in the instructions or indication of usage and for added warnings and precautions. The fact that an organization or website is referred to in this work as a citation and/or potential source of further information does not mean that the author or the publisher endorses the information the organization or website may provide or recommendations it may make. Further, readers should be aware that websites listed in this work may have changed or disappeared between when this works was written and when it is read. No warranty may be created or extended by any promotional statements for this work. Neither the publisher nor the author shall be liable for any damages arising herefrom.

Library of Congress Cataloging-in-Publication Data

Names: Rachidi, Farhad, 1962– editor. | Rubinstein, Marcos, 1960– editor. | Paolone, Mario, 1973– editor. Title: Electromagnetic time reversal : application to electromagnetic compatibility and power systems / edited by, Farhad Rachidi, Marcos Rubinstein, Mario Paolone. Description: Hoboken, New Jersey : John Wiley & Sons, Inc., [2017] | Includes bibliographical references and index. Identifiers: LCCN 2016042856 (print) | LCCN 2016052640 (ebook) | ISBN 9781119142089 (cloth ; alk. paper) | ISBN 1119142083 (cloth ; alk. paper) | ISBN 9781119142096 (Adobe PDF) | ISBN 9781119142102 (ePub) Subjects: LCSH: Time reversal. | Electromagnetism. | Electromagnetic compatibility. | Electric power systems. Classification: LCC QC173.59.T53 E44 2017 (print) | LCC QC173.59.T53 (ebook) | DDC 621.3101/53--dc23 LC record available at https://lccn.loc.gov/2016042856

Cover image: Kaisorn/Gettyimages                     Sylverarts/Gettyimages

“Lost time is never found again” Benjamin Franklin

CONTENTS

List of Contributors

Preface

About the Companion Website

1 Time Reversal: A Different Perspective

1.1 Introduction

1.2 What is Time?

1.3 Time Reversal or Going Back in Time

1.4 Application of Time Reversal in Practice

1.5 Refocusing of Electromagnetic Waves Using Time Reversal

1.6 Applications of Time Reversal in Electrical Engineering

Notes

References

2 Time Reversal in Diffusive Media

2.1 Introduction

2.2 Fundamental Properties of Diffusive Media

2.3 Time-Reversal Transmissions in Diffusive Media

2.4 Time Reversal for the Generation of Wavefronts

2.5 Final Considerations

References

3 From Electromagnetic Time-Reversal Theoretical Accuracy to Practical Robustness for EMC Applications

3.1 On the Interest of Time Reversal in the EMC Context

3.2 TR in Transmission Line (TL) Networks

3.3 Selective EMC Radiated Immunity

3.4 Towards Realistic EMC Testing

3.5 Conclusion

References

4 Amplification of Electromagnetic Waves Using Time Reversal

4.1 Outline

4.2 Introduction

4.3 Measurements

4.4 Theoretical Model

4.5 Comparison with a Directive Antenna

4.6 Discussion

4.7 Conclusion

References

5 Application of Time Reversal to Power Line Communications for the Mitigation of Electromagnetic Radiation

5.1 Introduction

5.2 Adaptation of Time Reversal to Power Line Communications

5.3 Experimental Study of Radiation Mitigation

5.4 Results and Statistical Analysis

5.5 Conclusion

References

6 Application of Electromagnetic Time Reversal to Lightning Location

6.1 Introduction

6.2 Overview of Lightning Location Techniques

6.3 EMTR and Lightning Location

6.4 Practical Implementation Issues

Notes

References

7 Electromagnetic Time Reversal Applied to Fault Location in Power Networks

7.1 Chapter Overview

7.2 Introduction

7.3 Summary of Existing Fault Location Methods

7.4 Application of Electromagnetic Time Reversal (EMTR) for the Fault Location Problem

7.5 The Issue of Losses: Back-Propagation Models

7.6 Experimental Validation

7.7 Case Studies and Performance Evaluation

7.8 Conclusion

Notes

References

Index

EULA

List of Tables

Chapter 3

Table 3.1

Table 3.2

Table 3.3

Chapter 7

Table 7.1

Table 7.2

Guide

Cover

Table of Contents

Preface

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List of Contributors

Pierre Bonnet

Blaise Pascal University

Andrea Cozza

Group of Electrical Engineering Paris (GeePs)

Matthieu Davy

University of Rennes

Julien de Rosny

Langevin Institute

Mathias Fink

Langevin Institute

Sébastien Lalléchère

Blaise Pascal University

Gaspard Lugrin

Swiss Federal Institute of Technology of Lausanne (EPFL)

Florian Monsef

Group of electrical engineering Paris (GeePs)

Michel Ney

Telecom Bretagne

Pascal Paganini

Telecom Bretagne

Françoise Paladian

Blaise Pascal University

Mario Paolone

Swiss Federal Institute of Technology of Lausanne (EPFL)

Farhad Rachidi

Swiss Federal Institute of Technology of Lausanne (EPFL)

Reza Razzaghi

Swiss Federal Institute of Technology of Lausanne (EPFL)

Marcos Rubinstein

University of Applied Sciences of Western Switzerland

Ahmed Zeddam

Orange Labs

Preface

Time reversal has emerged as a very interesting technique with potential applications in various fields of engineering. It has received a great deal of attention in recent years, essentially in the field of acoustics, where it was first developed by Prof. Fink and his team in the 1990s. In the past decade, the technique has also been used in the field of electromagnetics and applied to various other areas of electrical engineering. In particular, the technique has been successfully applied in the fields of electromagnetic compatibility (EMC) and power systems, leading to mature technologies in source-location identification with unprecedented performance compared to classical approaches. It is expected that the fields of application of electromagnetic time reversal (EMTR) will continue to grow in the near future.

This book is intended to give the theoretical foundation of the electromagnetic time-reversal theory. Special emphasis is given on real applications in the fields of EMC and power systems.

The book's introductory chapter presents the theoretical basis of the electromagnetic time-reversal technique. It starts with a discussion of the notion of time in physics and goes on to present three approaches that can be used to effectively make a system go back in time, in the sense that it retraces the path it came from in the immediate past. The concepts of strict and soft time-reversal invariance are introduced and illustrated using simple examples. The time-reversal invariance of physics laws is then described, with special attention given to the time-reversal invariance of Maxwell's equations. The concept of time-reversal cavity and the use of time reversal as a means of refocusing electromagnetic waves is then described. The chapter ends with a brief presentation of application areas of electromagnetic time reversal.

Chapters 2 to 7 are devoted to specific applications of EMTR, including EMC measurements, EM field focusing and amplification, interference mitigation in power line communications, lightning detection, and fault location in power systems.

In Chapter 2, the potential use of time reversal in diffusive media for radiative testing is addressed, in particular for EMC, antenna testing, and channel emulation. The chapter starts with a brief review of common features of diffusive media, introducing probabilistic models for the random nature of fields in them, showing the complexity of the media and making the case for the generation of coherent wavefronts. The response of a diffusive medium to time-reversed signals is then analyzed for point-to-point transmissions, illustrating how received signals are affected by background random fluctuations due to the frequency-selective response of the medium. It is shown that narrow bandwidths are sufficient to enable the properties of time reversal, a point that is of fundamental importance in high-power microwave applications. Other properties are then presented, including the possibility of using single-antenna time-reversal (TR) mirrors and the ability of TR to control the polarization of received fields, independent of the features of the transmitting antenna. In addition, spatial and time focusing are shown to lead to energy efficiencies even higher than those expected in reverberation chambers. Virtual sources are introduced based on the observation that standard TR assumes the availability of sources of radiation whose fields will then be time-reversed. In the final part of the chapter, a generalization of TR is presented that allows the generation of complex, arbitrary wavefronts.

Chapter 3 deals with the robustness of the EMTR process for EMC applications. A number of studies have been carried out covering a broad range of domains, including communications, imaging, and field enhancement. In this framework, electromagnetic compatibility (EMC) may stand to benefit greatly from EMTR, since this technique allows a heretofore-unachievable level of control of electromagnetic waves. This could reduce time and costs during EMC standard tests, assuming that external conditions (antenna location, environment, devices under test) are perfectly known. Few studies have dealt with the potential impact of randomness on EMTR. In this chapter, the main emphasis will be on the accuracy and robustness of using EMTR in practical experiments dealing with immunity, controlling EM fields, and transmission lines.

Traditional focusing systems of wideband signals make use of a beamforming method applied to an array of antennas. In Chapter 4, a different approach, based on the time-reversal technique, is presented to focus high-amplitude wideband pulses. The time-reversal process consists of two phases. First, the transient response between a source outside a cavity and an array of antennas within the cavity is measured. For wideband pulses, the signals spread over a time much longer than the initial pulse length because of the reverberation within the cavity. The signals are then flipped in time and re-emitted. Due to the reversibility of the wave in the propagation medium, the time-reversed field focuses both in time and space at the initial source position. The gain in amplitude of the focused signal is linked to the time compression of the transient response and can therefore be several orders of magnitude higher than the amplitude generated using a beamforming method without the chamber. An analysis of the properties of the focal spot with respect to the different experimental parameters, such as the number of antennas, the aperture, and the size of the cavity or the source polarization is presented. The one-bit time-reversal method to enhance the amplitude of the focused signal is also described. Finally, we show an extension of the method to focus a pulse at any position outside a cavity from the knowledge of the transient responses only in the aperture area.

Chapter 5 presents the use of the TR technique to mitigate radiated emissions from power line communication (PLC) systems. Power line communication is an effective response to today's high demand for multimedia services in the domestic environment, not only for its fast and reliable transfer characteristics but also for its flexible, low-cost implementation, since the PLC technology uses the existing electrical network infrastructure and the ubiquitous outlets throughout the home. In current PLC systems, the high bit rate transfer through the mains network generates acceptable radiated emissions regulated by international standards, but the demand for greater speeds in new generation PLC systems may cause higher levels of emissions. The way in which this method has been experimentally verified in real electrical networks is presented. The second part of this chapter presents the level of effectiveness of TR in reducing the average electromagnetic nterference (EMI) generated by PLC transmissions by combining the effects of channel gain and spatial filtering.

Chapter 6 is devoted to lightning location using EMTR. The first part of this chapter presents a brief overview of the main classical lightning location techniques. Next, the lightning location by the EMTR method is described, followed by a mathematical proof and simulation-based verifications. Then the important issue of the application of EMTR in the presence of losses due to propagation over a finitely conducting ground is dealt with. The relation between EMTR and the difference in time-of-rrival technique is also presented. The last part of the chapter is dedicated to practical implementation issues.

In Chapter 7, we present the use of the EMTR theory for locating faults in both transmission and distribution power networks characterized by meshed and radial topologies. The fault location functionality is an important online process required by power systems operation since, for the case of transmission grids, it has a large influence on the security and, for distribution systems, on the quality of supply. Compared to other transient-based fault location techniques, the EMTR method presents a number of advantages, namely, its straightforward applicability to inhomogeneous media (mixed overhead and coaxial power cable lines), the use of a single observation (measurement) point, and robustness against fault type and fault impedance. All these aspects are presented and discussed in the chapter via simulations and experimental validations of the EMTR-based fault location process.

To the best of our knowledge, this is the first book giving an overview of the EMTR technique and its engineering applications to power systems and EMC. Within the context of the evolution of power networks towards smart grids and the importance of the security and reliability of future grids, we are convinced that EMTR-based techniques described in the book and possibly others developed in the future will find an ever growing field of application.

The editors are indebted to many individuals for their support, advice, and guidance. Special thanks are due to Steven Anlage, Giulio Antonini, Gerhard Diendorfer, Jean Mahseredjian, Hamid Karami, Carlo Alberto Nucci, Antonio Orlandi, Wolfgang Schulz, Keyhan Sheshyekani, Mirjana Stojilovic, Felix Vega, and Yan-Zhao Xie, and to all the authors of the chapters for their precious contributions. Thanks are also due to Asia Codino, Gaspard Lugrin, Hossein M. Manesh, Razieh Moghimi, Nicolas Mora, Andrea Pollini, Reza Razzaghi, and Zhaoyang Wang, who have worked on various aspects of electromagnetic time reversal during their graduate studies, and to undergraduate students Amir Fouladvand and Dara Sadeghi.

Farhad Rachidi, Marcos Rubinstein, and Mario Paolone

About the Companion Website

Electromagnetic Time Reversal: Application to EMC and Power Systems is accompanied by a companion website:

www.wiley.com/go/rachidi55

The website includes: