The death of Professor Arthur Wright in the summer of 1996 deprived me
of a friend and a colleague whose judgement and experience shaped this
book. I pay tribute to his contributions to protection and electrical
engineering education. In the five years since the first edition
appeared, many developments have taken place and it is now necessary to
update the book. The use of digital communications and advanced signal
processing techniques is now widespread and several fully numeric relays
are available from manu- facturers. Two new Chapters 13 and 14 have been
added to introduce readers to these concepts and associated techniques.
Artificial intelligence is making its impact in all engineering
applications and power system protection is no exception. Expert
systems, fuzzy logic, artificial neural networks, adaptive and
integrated protection, synchronized measurements using the global
positioning system, genetic algorithms, flexible a.c. transmission
systems, are some of the techniques considered in connection with
protection. Although many of these techniques have not yet found major
application in protection, it is nevertheless essential for the educated
protection engineer to have a basic understanding of the underlying
principles and methodology so that he, or she, can evaluate their
suitability for new relaying problems and applications. Chapter 15 was
therefore added to guide readers through this developing area. I have
also added some new material in other chapters to reflect changes over
the past years.
