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HARMONICS AND POWER SYSTEMS Copyright 2006 by Taylor & Francis Group, LLC The ELECTRIC POWER ENGINEERING Series Series Editor Leo L. Grigsby Published Titles Electric Drives Ion Boldea and Syed Nasar Linear Synchronous Motors: Transportation and Automation Systems Jacek Gieras and Jerry Piech Electromechanical Systems, Electric Machines, and Applied Mechatronics Sergey E. Lyshevski Electrical Energy Systems Mohamed E. El-Hawary Distribution System Modeling and Analysis William H. Kersting The Induction Machine Handbook Ion Boldea and Syed Nasar Power Quality C. Sankaran Power System Operations and Electricity Markets Fred I. Denny and David E. Dismukes Computational Methods for Electric Power Systems Mariesa Crow Electric Power Substations Engineering John D. McDonald Electric Power Transformer Engineering James H. Harlow Electric Power Distribution Handbook Tom Short Synchronous Generators Ion Boldea Variable Speed Generators Ion Boldea Harmonics and Power Systems Francisco C. De La Rosa Copyright 2006 by Taylor & Francis Group, LLC HARMONICS AND POWER SYSTEMS Francisco C. De La Rosa Distribution Control Systems, Inc. Hazelwood, Missouri, U.S.A. Copyright 2006 by Taylor & Francis Group, LLC 3016_Discl.fm Page 1 Tuesday, January 17, 2006 11:55 AM Published in 2006 by CRC Press Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2006 by Taylor & Francis Group, LLC CRC Press is an imprint of Taylor & Francis Group No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-10: 0-8493-3016-5 (Hardcover) International Standard Book Number-13: 978-0-8493-3016-2 (Hardcover) Library of Congress Card Number 2005046730 This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. No part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC) 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data De la Rosa, Francisco. Harmonics and power systems / by Francisco De la Rosa. p. cm. Includes bibliographical references and index. ISBN 0-8493-3016-5 1. Electric power systems. 2. Harmonics (Electric waves) I. Title. TK3226.D36 2006 621.31’91--dc22 2005046730 Visit the Taylor & Francis Web site at http://www.taylorandfrancis.com Taylor & Francis Group is the Academic Division of Informa plc. Copyright 2006 by Taylor & Francis Group, LLC and the CRC Press Web site at http://www.crcpress.com 3016_book.fm Page v Monday, April 17, 2006 10:36 AM To the memory of my father and brother To my beloved mother, wife, and son Copyright 2006 by Taylor & Francis Group, LLC 3016_book.fm Page vii Monday, April 17, 2006 10:36 AM Preface This book seeks to provide a comprehensive reference on harmonic current generation, propagation, and control in electrical power networks. Harmonic waveform distortion is one of the most important issues that the electric industry faces today due to the substantial volume of electric power that is converted from alternating current (AC) to other forms of electricity required in multiple applications. It is also a topic of much discussion in technical working groups that issue recommendations and standards for waveform distortion limits. Equipment manufacturers and electric utilities strive to find the right conditions to design and operate power apparatuses that can reliably operate in harmonic environments and, at the same time, meet harmonic emission levels within recommended values. This book provides a compilation of the most important aspects on harmonics in a way that I consider adequate for the reader to better understand the subject matter. An introductory description on the definition of harmonics along with analytical expressions for electrical parameters under nonsinusoidal situations is provided in Chapter 1 as a convenient introductory chapter. This is followed in Chapter 2 by descriptions of the different sources of harmonics that have become concerns for the electric industry. Industrial facilities are by far the major producers of harmonic currents. Most industrial processes involve one form or another of power conversion to run processes that use large direct current (DC) motors or variable frequency drives. Others feed large electric furnaces, electric welders, or battery chargers, which are formidable generators of harmonic currents. How harmonic current producers have spread from industrial to commercial and residential facilities — mostly as a result of the proliferation of personal computers and entertaining devices that require rectified power — is described. Additionally, the use of energy-saving devices, such as electronic ballasts in commercial lighting and interruptible power supplies that provide voltage support during power interruptions, makes the problem even larger. As this takes place, standards bodies struggle to adapt present regulations on harmonics to levels more in line with realistic scenarios and to avoid compromising the reliable operation of equipment at utilities and customer locations. The most important and widely used industry standards to control harmonic distortion levels are described in Chapter 3. The effects of harmonics are thoroughly documented in technical literature. They range from accelerated equipment aging to abnormal operation of sensitive processes or protective devices. Chapter 4 makes an effort to summarize the most relevant effects of harmonics in different situations that equally affect residential, commercial, and industrial customers. A particular effort is devoted to illustrating the effects of harmonics in electrical machines related to pulsating torques that can drive machines into excessive shaft vibration. Copyright 2006 by Taylor & Francis Group, LLC 3016_book.fm Page viii Monday, April 17, 2006 10:36 AM Given the extensive distribution of harmonic sources in the electrical network, monitoring harmonic distortion at the interface between customer and supplier has become essential. Additionally, the dynamics of industrial loads require the characterization of harmonic distortion levels over extended periods. Chapter 5 summarizes the most relevant aspects and industry recommendations to take into account when deciding to undertake the task of characterizing harmonic levels at a given facility. One of the most effective methods to mitigate the effect of harmonics is the use of passive filters. Chapter 6 provides a detailed description of their operation principle and design. Single-tuned and high-pass filters are included in this endeavor. Simple equations that involve the AC source data, along with the parameters of other important components (particularly the harmonic-generating source), are described. Filter components are determined and tested to meet industry standards’ operation performance. Some practical examples are used to illustrate the application of the different filtering schemes. Because of the expenses incurred in providing harmonic filters, particularly but not exclusively at industrial installations, other methods to alleviate the harmonic distortion problem are often applied. Alternative methods, including use of stiffer AC sources, power converters with increased number of pulses, series reactors, and load reconfiguration, are presented in Chapter 7. In Chapter 8, a description of the most relevant elements that play a role in the study of the propagation of harmonic currents in a distribution network is presented. These elements include the AC source, transmission lines, cables, transformers, harmonic filters, power factor, capacitor banks, etc. In dealing with the propagation of harmonic currents in electrical networks, it is very important to recognize the complexity that they can reach when extensive networks are considered. Therefore, some examples are illustrated to show the convenience of using specialized tools in the analysis of complicated networks with multiple harmonic sources. The penetration of harmonic currents in the electrical network that can affect adjacent customers and even reach the substation transformer is also discussed. Finally, a description of the most important aspects to determine power losses in electrical equipment attributed to harmonic waveform distortion is presented in Chapter 9. This is done with particular emphasis on transformers and rotating machines. Most of the examples presented in this book are based on my experience in industrial applications. I hope this book provides some useful contribution to the understanding of a complex phenomenon that can assist in the solution of specific problems related to severe waveform distortion in electrical power networks. Francisco C. De La Rosa Copyright 2006 by Taylor & Francis Group, LLC 3016_book.fm Page ix Monday, April 17, 2006 10:36 AM Acknowledgments My appreciation for the publication of this book goes first to my family for their absolute support. Thanks to Connie, my wife, for bearing with me at all times and especially during the period when this book was written, for the many hours of sleep she lost. Thanks to Eugene, my son, for being patient and considerate with me when I was unable to share much time with him, especially for his positive and thoughtful revision of many parts of the book. His sharp and judicious remarks greatly helped me better describe many of the ideas found in this book. To produce some of the computer-generated plots presented in the course of the book, I used a number of software tools that were of utmost importance to illustrate fundamental concepts and application examples. Thanks to Professor Mack Grady from the University of Texas at Austin for allowing me to use his HASIP software and to Tom Grebe from Electrotek Concepts, Inc. for granting me permission to use Electrotek Concepts TOP, The Output Processor®. The friendly PSCAD (free) student version from Manitoba HVDC Research Centre Inc. was instrumental in producing many of the illustrations presented in this book and a few examples were also generated with the free Power Quality Teaching Toy Tool from Alex McEachern. Copyright 2006 by Taylor & Francis Group, LLC 3016_book.fm Page xi Monday, April 17, 2006 10:36 AM The Author Francisco De La Rosa, presently a staff scientist at Distribution Control Systems, Inc. (DCSI) in Hazelwood, Missouri, holds BSc and MSc degrees in industrial and power engineering from Coahuila and Monterrey Technological Institutes in Mexico, respectively and a PhD degree in electrical engineering from Uppsala University in Sweden. Before joining the Advanced Systems and Technology Group at DCSI, an ESCO Technologies Company, Dr. De La Rosa conducted research, tutored, and offered engineering consultancy services for electric, oil, and steel mill companies in the United States, Canada, Mexico, and Venezuela for over 20 years. Dr. De La Rosa taught electrical engineering courses at the Nuevo Leon State University in Monterrey, Mexico as an invited lecturer in 2000–2001. He holds professional membership in the IEEE Power Engineering Society where he participates in working groups dealing with harmonics, power quality, and distributed generation. Copyright 2006 by Taylor & Francis Group, LLC 3016_book.fm Page xiii Monday, April 17, 2006 10:36 AM Contents Chapter 1 Fundamentals of Harmonic Distortion and Power Quality Indices in Electric Power Systems ......................................................1 1.1 1.2 1.3 Introduction ......................................................................................................1 Basics of Harmonic Theory .............................................................................2 Linear and Nonlinear Loads ............................................................................3 1.3.1 Linear Loads ........................................................................................4 1.3.2 Nonlinear Loads...................................................................................6 1.4 Fourier Series ...................................................................................................9 1.4.1 Orthogonal Functions.........................................................................12 1.4.2 Fourier Coefficients............................................................................13 1.4.3 Even Functions...................................................................................13 1.4.4 Odd Functions ....................................................................................13 1.4.5 Effect of Waveform Symmetry ..........................................................14 1.4.6 Examples of Calculation of Harmonics Using Fourier Series ..........14 1.4.6.1 Example 1 ...........................................................................14 1.4.6.2 Example 2 ...........................................................................15 1.5 Power Quality Indices under Harmonic Distortion.......................................17 1.5.1 Total Harmonic Distortion .................................................................17 1.5.2 Total Demand Distortion....................................................................17 1.5.3 Telephone Influence Factor TIF.........................................................18 1.5.4 C Message Index................................................................................18 1.5.5 I * T and V * T Products ...................................................................18 1.5.6 K Factor..............................................................................................19 1.5.7 Displacement, Distortion, and Total Power Factor ...........................19 1.5.8 Voltage-Related Parameters ...............................................................20 1.6 Power Quantities under Nonsinusoidal Situations ........................................20 1.6.1 Instantaneous Voltage and Current ....................................................20 1.6.2 Instantaneous Power...........................................................................21 1.6.3 RMS Values........................................................................................21 1.6.4 Active Power ......................................................................................21 1.6.5 Reactive Power...................................................................................21 1.6.6 Apparent Power..................................................................................21 1.6.7 Voltage in Balanced Three-Phase Systems........................................22 1.6.8 Voltage in Unbalanced Three-Phase Systems ...................................23 References................................................................................................................25 Copyright 2006 by Taylor & Francis Group, LLC