Preface

Nuclear power approximately supplies a sixth of the world's electricity and considers as the major source of "carbon-free" energy today. With growing concerns about global warming, it is not surprising that governments and power providers around the world are considering building a substantial number of additional nuclear power plants. These plants have demonstrated remarkable reliability and efficiency with the help of extensive research work and sharing operational practical experience. Therefore, the materials of this book are collected with emphasis on the practical aspects of modern nuclear power around the world. However, the presentation is not entirely technical because, there are several research factors that also influence the subject matter. The book identifies and analyzes major practical issues in nuclear energy. It is not a basic nuclear engineering design book of which there are already many good ones. Instead the materials are compiled in this book with practical background in mind. Experiences from several nuclear power plants and research institutions are gathered to present best engineering analyses, research effort and practice with as little prejudice as possible. Although several technical books restrict themselves to technical matters and avoid research aspects, the nuclear power technology subject has received a great attention by many research institutes. Therefore, the current book is presenting several important areas in nuclear energy from practical prospective with some research and scientific flavor.

> **Wael Ahmed**  King Fahd University of Petroleum & Minerals, Saudi Arabia

**Chapter 1** 

© 2012 Lee and Chen, licensee InTech. This is an open access chapter distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

© 2012 Lee and Chen, licensee InTech. This is a paper distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/3.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

**Power System Protection Design for NPP** 

One of the key purposes of NPP power system protection is to ensure that NPP's local power demand (such as cooling pumps, control systems, etc.) are met under all circumstances even during faulted periods. To achieve this goal, NPP power system protection must ensure that it can supply these local loads using either (1) power from the grid (via the transmission connection, which in most time, however, are used for exporting the excess power generated by the NPP after supplying its local loads) or (2) power from local generations such as diesel generators, batteries, etc. at all times and under all

On the first power source (grid power), many NPPs worldwide have been built along the seashore for cooling water availability reasons. Overhead transmission lines are thus built in the vicinity of the seashore to transport the large amount of power generated from the NPP to the grid economically. As these overhead lines are exposed to salt contamination, flashover will occur when contamination becomes excessive. In the event of flashover, which is equivalent to a line-to-ground fault, the plant's protection system will need to initiate a series of switching operation to redirect the large power output from the NPP to a backup route in order to avoid reactor emergency shut-down. However, such switching has the adverse effect of causing undesirable transient overvoltages to propagate in the plant's local power grid [1-4]. Dealing with the frequent switching actions of these overhead lines while mitigating their adverse effects thus becomes the first challenge of designing NPP

Once the NPP loses its connection to the grid, it will need to rely on the local generation to continue supplying its local loads. Most NPP use multiple "independent" sources as backup power. However, unless NPP's local power grid is properly configured and its protection system properly designed, these "independent" sources can all fail at the same time as

manifested in Taipower's 18 March, 2001 Level 2 event ("318 Event") [5].

Chang-Hsing Lee and Shi-Lin Chen

http://dx.doi.org/10.5772/50557

**1. Introduction** 

circumstances.

power system protection.

Additional information is available at the end of the chapter
