Preface

In the area of control engineering, it is necessary to work in a continued form in obtaining new methods of regulation to remedy the problem that already exists or to find better alter‐ natives to which they were used previously.

The economic agents now realize knowledge as an active relavant for the market organiza‐ tion differentiation. This scenario explains the need for systems that assist the user in the ac‐ quisition process and knowledge management. Intelligent systems, known as expert sys‐ tems, serve to this purpose in the extent that they have signed as facilitators in this process. These are systems that are based on expert knowledge, on any subject, in order to emulate human expertise in the specific field. To obtain this knowledge, the knowledge engineers, also called software engineers, need to develop methodologies for intelligent systems. In this area there is still no unified methodology that provides effective methods, notations and tools to aid in development. The use of the recommendations helps the designer to interface with more knowledge giving the possibility to access them in an automated fashion and with various features, resulting in better recommendations and with best models specified by users.

In developing of nonlinear expert system simulation models, the proper selection of input variables is a challenging problem. Therefore, a false combination of input variables could prevent the simulation model from achieving the optimal solution. The presented methodol‐ ogy in this book is an applicable approach for input variable selection in multi-input simula‐ tors of expert systems.

This book has 5 chapters and explains that the expert systems are products of the artificial intelligence, branch of computer science that seeks to develop intelligent programs for hu‐ man, materials and automation.

#### **Professor Eng. Petrică Vizureanu, Ph.D.**

Director of the Department of Technologies and Equipment for Materials Processing Faculty of Materials Science & Engineering "Gheorghe Asachi" Technical University of Iasi Romania

**Section 1**

**Industrial Applications**

**Industrial Applications**

**Chapter 1**

**Intelligent Systems for the Detection of Internal Faults**

This chapter presents an approach based on expert systems, which is intended to identify and to locate internal faults in power transformers, as well as to provide an accurate diag‐ nosis (predictive, preventive and corrective), so that proper maintenance can be per‐ formed. In fact, the main difficulty in using conventional methods, based on analysis of acoustic emissions or dissolved gases, lies in how to relate the measured variables when there is an internal fault in a transformer. This kind of situation makes it difficult to de‐ sign optimized systems, because it prevents the efficient location and identification of pos‐ sible defects with sufficient rapidity. In addition, there are many cases where the equipment must be turned off for such tests to be carried out. Thus, this chapter proposes an architec‐ ture for an intelligent expert system for efficient fault detection in power transformers us‐ ing different diagnosis tools, based on techniques of artificial neural networks and fuzzy inference systems. Based on acoustic emission signals and the concentration of gases present in insulating mineral oil and electrical measurements, intelligent expert systems are able to provide, as a final result, the identification, characterization and location of any electrical

With the changes occurring in the electricity sector, there is a special interest on the part of power transmission companies in improving and defining strategies for the maintenance of power transformers. However, when a fault occurs in a transformer, it is generally removed from the system and sent to a maintenance sector to be repaired. With this in mind, some

> © 2012 da Silva et al.; licensee InTech. This is an open access article 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 da Silva et al.; 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.

**in Power Transmission Transformers**

Ivan N. da Silva, Carlos G. Gonzales,

Danilo H. Spatti and José A. C. Ulson

http://dx.doi.org/10.5772/51417

fault occurring in transformers.

**1. Introduction**

Rogério A. Flauzino, Paulo G. da Silva Junior,

Additional information is available at the end of the chapter

Ricardo A. S. Fernandes, Erasmo S. Neto,
