Preface
This is an academic book on power system protection. It was prepared to serve as an introductory text in power system protection for graduate students in Electric Power Systems. The present edition is the outgrowth of previous editions that have been used by several universities for 25 years.
There is a fundamental problem in developing a graduate course in power system protection at a university. Most faculty members are not experts at relaying, and very few practice this art on a regular basis. Without consistent contact with the field, it is difficult to keep up-to-date, particularly with respect to new relay hardware. But there is a more fundamental problem in this regard. One has to question whether the teaching of protection hardware and relay settings is appropriate material for academic study. Therefore, I chose to concentrate on the analytical techniques that are useful in system protection, with very little emphasis on the hardware that is used to implement a protective scheme. Analysis is one subject that the university professor can teach with authority, and is one that many practicing engineers need to understand more thoroughly. Therefore, it is hoped that this book will be of value to both the graduate student and the practicing protection engineer.
In writing a book such as this, the writer stands on the shoulders of giants. I was greatly influenced in the preparation of this work by the excellent texts that have been available for some time. The fine book by Mason stands as a classic in this field and is a necessary reference. The excellent books of Warrington are recommended as references, particularly because of their thorough coverage of relay hardware, a subject that is purposely omitted here. The fine book by Atabekov is recommended for its excellent analytical treatment. The excellent work of Horowitz and Phadke provides an authoritative treatment of the subject that is recommended. Finally, the manufacturers all publish very good material on relays and relay applications. Several of these documents are referenced throughout the book.
The treatment of the subject is presented at the graduate level; that is, it is assumed that the reader has a bachelor's degree in electrical engineering. Moreover, it is assumed that the reader has mastered those power system fundamentals that are covered in the excellent introductory books of Stevenson and Grainger, Gross, Neuenswander, Gönen, and El-Hawary.
These fundamentals are not reviewed here. It is also presumed that the reader is familia symmetrical components and with the mathematical principles of functions of a compl. able. We also assume that the reader is familiar with computers and computer program such that the computer can be used as a tool in problem solving.
This book has been under development for at least 25 years. The author taught subject for many years and shared his notes with professors from other universities comments were gratifying, and encouraged the development of a full textbook on the sub of system protection. There is no doubt that protection is one of the most demanding technical subjects in power systems, and protection engineers are a breed apart. The author shares an intense interest in the subject with these masters of the art and science of protection. Most of the engineers who practice power system protection learn this craft by practical application the author included. There is an opportunity, however, for the academic pursuit of protection as a science in its own right. Therefore, I hope this book assists those who make this study their life's work-a noble pursuit and one that I enthusiastically recommend.
A family of computer programs is included as an attachment to the book. These programs are briefly described as follows:
STUFLT A student fault program that includes a feature for finding the fault equivalent for any network branch, as described in Chapter 5. RELAY A small computer program used to compute the fault current and apparent impedance for a three-phase fault placed at any location along a series compensated transmission line. See Chapter 15 for examples. PWRMAT A program developed by the power faculty at lowa State University to perform complex matrix analysis typical of power system problems. A maximum of 30 complex matrices of up to 400 elements can be stored and manipulated. FREQ A program used to compute the frequency trajectory as a function of time following the islanding of a portion of a power system, where the island has an imbalance between generation and load. Problems of this type are described in Chapter 20, and this program was used for the computations of frequency vs. time found in that chapter.
Once data files are constructed as text files and named, the user simply double-clicks on the program icon and identifies the data file by name in order to launch the computation and view the results. Typical data files are provided for all programs so that the reader can duplicate text computations or produce results for similar problems of interest. Brief descriptive manuals are provided for all of the programs.
P. M. Anderson Power Math Associates, Inc.