Plenary Lecture

Vibro-acoustic Techniques to Diagnose Complex Electromechanical Structures

Professor Francesco Muzi
Department of Electrical Engineering and Computer Science
University of L’Aquila
ITALY
E-mail: muzi@ing.univaq.it
Web site: http://www.diel.univaq.it/people/muzi/

Abstract: A diagnostics procedure based on signal processing of acoustic emissions aimed at investigating complex electromechanical structures is presented. Acquired signals emitted by a structure can be activated by either natural or artificial stimuli; when using artificial and known stimuli, that is to say, stimuli linked to a set of parameters representing “state vectors”, the diagnostic method may prove to be very accurate. Signals are processed through the following stages: acquisition, segmentation, parameterization, classification and recognition. An a priori definition of the possible classes to which the system under investigation might belong is required. By means of a consultation of a predefined digital vocabulary of possible anomalies, the analysis process establishes the statistical “closeness” of the case examined to a reference model in the vocabulary and subsequently identifies the belonging class of the apparatus under checking. If the involved physical phenomena are well known, the classification can be performed using knowledge-based techniques, otherwise statistical procedures are recommended. In the past, diagnostic processes allowed to define only the object state at the moment of the investigation; nowadays, thanks to the availability of low-cost, huge digital memories and relevant power computation, the diagnostics processes allow also to predict the residual life expectation of complex jointed structures. The proposed monitoring and diagnostic method allows a time-by-time assessment of the evolution of power system components from the installation to their life end. The normal operating apparatuses can be monitored and checked from a remote, dedicated diagnostic center where information is received directly from the field. The suggested monitoring and diagnostic system allows one to usefully schedule preventative maintenance, reduce costs, and improve the quality of electric power systems. Many complex structures were examined, and some relevant real diagnostics cases concerning power transformers, power circuit breakers, and transiting electric trains are illustrated and discussed.



Brief Biography of the Speaker:
Francesco Muzi is a professor of Power Systems at the University of L’Aquila, Italy, where he has also the scientific responsibility for the Power System Group. His main research interests concern Power systems transients and dynamics, Power quality in distribution systems, Power system reliability, Electromagnetic analysis, and Power systems diagnostics and protection. In these fields, he authored or co-authored over 100 scientific papers published in reviewed journals or presented at international conferences. For his contribution on Lightning Induced Overvoltages, he received mentions in books edited by John Wiley & Sons, New York and participated to the outline of the “IEEE Guide for improving the lightning performance of electric lines”, IEEE Standards Department, New York. He has also a patent for an industrial invention, namely “Power system controlled by a microprocessor”. He is a regional chairman of the Italian National Lighting Society and was a chairman or keynote lecturer in a number of international conferences organized by ISSAT (International Society of Science and Applied Technologies) and WSEAS. He is a technical reviewer for the following international journals: IEEE Transactions on Power Delivery, Electric Power Systems Research by Elsevier Science, IET Generation, Transmission & Distribution.