Power Systems For further volumes: http://www.springer.com/4622 Thomas Worzyk Submarine Power Cables Design, Installation, Repair, Environmental Aspects 123 Thomas Worzyk 370 30 Rödeby/Sweden [email protected] Office: ABB AB High Voltage Cables 371 23 Karlskrona/Sweden [email protected] ISSN 1612-1287 e-ISSN 1860-4676 ISBN 978-3-642-01269-3 e-ISBN 978-3-642-01270-9 DOI 10.1007/978-3-642-01270-9 Springer Dordrecht Heidelberg London New York Library of Congress Control Number: 2009927023 © Springer-Verlag Berlin Heidelberg 2009 This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically the rights of translation, reprinting, reuse of illustrations, recitation, broadcasting, reproduction on microfilm or in any other way, and storage in data banks. Duplication of this publication or parts thereof is permitted only under the provisions of the German Copyright Law of September 9, 1965, in its current version, and permission for use must always be obtained from Springer. Violations are liable to prosecution under the German Copyright Law. The use of general descriptive names, registered names, trademarks, etc. in this publication does not imply, even in the absence of a specific statement, that such names are exempt from the relevant protective laws and regulations and therefore free for general use. Cover design: deblik, Berlin Printed on acid-free paper Springer is part of Springer Science+Business Media (www.springer.com) Preface Submarine power cables have always been the unknown cousins of the submarine telecom cables. Telecom cables encircle the globe through all oceans in an enormous mesh, and have attracted public attention since the first Channel cable was laid in 1850. While the heroes of the first Atlantic telecom cable have been sung in numer- ous books, the feats of submarine power cable technology were rarely respected outside a small community. However, submarine power cables have their own characteristics and peculiari- ties. Cable design has developed during the decades. The evolution of manufacturing and installation technology allows for projects that, 20 years ago, were considered impossible. New performance records in system length, water depth, transmission power, or profits from the operation of submarine power cables are set every few years. Owing to this development, more submarine power cable projects are eco- nomically viable, or even possible. New applications for submarine power cables appear while known applications are pursued on a larger scale. Submarine power cables draw the attention of larger circles. Ten years ago only power utility engineers and cable ship crews were interested in submarine power cables. Possibly some fishermen uttered unprintable comments on them when they had entangled their fishing gear. Today, in the wake of new applications, submarine power cables have come into the focus of larger groups. The engineers of oil-and- gas companies have been interested a while, and increasing offshore activities, as well as the need for more power supply from shore to platform have promoted their involvement in the field. Most of all the fast development of offshore wind power brought submarine power cables to the attention of new quarters outside the power utilities. Investors and project developers need knowledge on the subject in order to analyse the technical and economical feasibility of offshore wind farms, as the cable costs can make up to forty per cent of the project costs, and cable installation can have a substantial impact on the overall schedule. Great commercial opportunities in power trading triggered the curiosity of Transmission System Operators (TSO) and power traders about opportunities and limitations of submarine power trans- mission lines. Regulators and authorities are getting more involved into submarine power cables, as permit applications continue to roll in. Also environmental groups and organisations now have to deal with submarine power cables, which sometimes are installed in sensitive areas. Satisfying enough, more students of all levels are v vi Preface getting involved into submarine power transmission as they study the possibilities of renewables. Even lawyers have developed an occupational interest in these cables. The idea to prepare this book actually came when I received many questions from the new audience, which demonstrated that there was need for a comprehen- sive introduction into the matter. For those who want to dig deeper into the issue it is not always easy to find relevant information. Much needed information about design and installation is scarce. Most textbooks on cables deal with land cables and leave only little space to submarine power cables, sometimes relegating them into their “Miscellaneous” chapter. Other cable textbooks are simply outdated neglecting state-of-the-art manufacturing and installation techniques. When I put this book together, I had to face several difficulties. Evaluating pub- lished reports and peer discussions, it became clear that the willingness for sharing experiences has decreased strongly. Information on submarine power cable opera- tions have been shared in journal papers quite openly until the 1990s, while reports about recent projects rarely address “lessons learned”. At a time when investor rela- tions, quarterly reports, and insurance issues prevail, few cable operators like to go public with accounts of detailed technical issues, problems, and fixes. However, the entire community of investors, grid operators, manufacturers, installers etc. would profit from an openhearted dialogue. This book aims at conveying a basic knowledge on the design, manufacture, and installation of submarine power cables. In 1903, cable engineer Dr. C. Baur wrote in the preface to his cable book: “the amount of knowledge related to the electric cable is so large that no single man can comprehend it”. This must be even more correct for submarine power cables. I must most humbly admit that I could only grasp and compile a fraction of the knowledge on the subject, relying on the assistance and help of many colleagues. For those who want to go further the reference lists may be helpful. I owe a lot of gratitude to those who assisted in the development of this book. Most of all, at this prominent place of the book, I want to take the opportunity to thank my dear wife for her enormous patience and my sons for their valuable input from their point of view. Acknowledgments I am indebted to many people and companies who helped me to bring this book on its way and into a reasonable form. I want to make a point of thanking all of them at this occasion. Although the production of this book was my private adventure, my employer ABB/Sweden provided me with a grant for literature and xerox copies. My col- leagues let me participate in their enormous and priceless knowledge and expe- rience, just to contribute to this book. Peter Sunnegardh, Anders Gustafsson and Johan Karlstrand supported me with their most valuable comments. Other cable manufactures gave me indepth information. I want to express my gratitude to Prysmian/Italy, Norddeutsche Seekabelwerke NSW/Germany and NKT Cables/Denmark for their generous assistance. The power utilities Statnett/Norway, Long Island Power Authority/USA, and Baltic Cable/Sweden contributed with information on cable service experiences and other. HT Suen, John Savio and Jan Brewitz were ever so cooperative. A book cannot be completed without the involvement of certain individuals who are conducive with illustrations, knowledge, anecdotes, good advice, or something else – or a bit of all of this. I would like to thank Lars Aksel Solberg and Janne Stark for a good story, Bill Burns for background info, Walter Paul and Jaeyoung (Jay) Lee for most interesting facts. Lydia Stark and Stephen Wigginton helped me to improve the writing language. The challenging task of transforming my writing into readable English was per- formed by Jochen U. Frankl, of Keryx Translations/Germany. A number of other companies helped me out with much needed photographs. Commercial and non-commercial marine organisations, from all around the world, have played a decisive role in the improvement of this book. The list is here: ABB Oy, Finland; ABB AB, Sweden; Baltic Cable AB, Sweden; Borealis, Swe- den; IHC Engineering Business Ltd, UK; International Cable Protection Committee, UK; LD Travocean, France; Long Island Power Authority, USA; Minerals Manage- ment Service, U.S. Department of the Interior, USA; National Institute of Water & Atmospheric Research Ltd, New Zealand; NKT Cables A/S, Denmark; NSW, Germany; Oceanteam Power and Umbilicals, UK; Prysmian, Italy; Statnett, Nor- way; Submarine Telecom Forum, UK; Trelleborg, UK; Woods Hole Oceanographic Institution, USA. vii Contents 1 Applications of Submarine Power Cables ......................... 1 1.1 Power Supply to Islands.................................... 1 1.2 Connection of Autonomous Grids . ..................... 3 1.3 OffshoreWindFarms...................................... 4 1.4 Supply of Marine Platforms . ............................ 5 1.5 Short-Haul Crossings . ................................... 6 1.6 Other Applications of Submarine Power Cables . .......... 6 References . .................................................. 7 2 Submarine Power Cables and Their Design Elements .............. 9 2.1 The Conductor . ....................................... 10 2.1.1 Solid Conductor . ............................ 10