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Our main objective in this thesis is to investigate three methods: Principal Component Analysis, Vector Space Model, and Signal Analysis, to establish system behaviours of an electromechanical system based on its historical operation data. The system behaviours are constituted by an aggregate number of similar actions which can be represented as patterns or clusters. The results show that we are also able to observe normal behaviours by interpreting a high percentage of similar actions inside patterns or clusters. Any deviations from the established normal behaviours could be interpreted as abnormal which warrant further investigation with respect to fault pre-emption and detection.

The stator inter-turn faults can result in catastrophic failure of the electric machines leading to extended downtime of the equipment, increased cost of repair and heavy financial losses in the industries. In the recent trends, online fault diagnosis of the electric machines that arc employed in critical applications has been considered very important since frequent outage of the machines for the purpose of testing cannot he recommended. In this work. diagnostic tools have been developed to unambiguously detect the early stages of these limits in the salient-pole synchronous machines. both reluctance synchronous machine and synchronous machine with DC excitation. Motor current signature analysis. a very useful tool in the condition monitoring of electrical machines. has been primarily used for this purpose. This study mainly consists of development of theoretical background for the diagnostic schemes followed by the implementation of these schemes on both simulated and experimental machines. For this purpose. detailed mathematical models of the synchronous machines have been developed that can include stator inter-turn faults with desired fault severity. The developed models can also accommodate some structural asymmetries of the machines. These models have been instrumental in testing the proposed diagnostic schemes under ideal conditions. Also. reversible stator inter-turn faults have been carefully created in the experimental machines to test the feasibility of the diagnostic schemes under practical conditions. In order to ensure unambiguous fault detection. a detailed analysis has been performed under various possible abnormal operating conditions of the machines such as supply unbalance. time harmonics and internal asymmetries of the machines. Initially. certain drawbacks have been identified in a diagnostic scheme based on negative sequence quantities of the machine and critical improvements have been suggested to enhance its sensitivity. However, the modified method fails to detect faults involving one turn short. Hence a frequency domain approach has been considered to detect these faults. As a first step in this direction, it has been demonstrated that the triplen harmonics in the line current of synchronous machines cannot detect these faults unambiguously. Subsequently, owing to the stored magnetic energy in the machine after supply disconnection, it has been observed that the triplen harmonics in the terminal voltages of RSM can be useful for unambiguous detection of stator inter-turn faults. A new and very effective technique of online fault detection. based on the monitoring of some specific frequency components in the field current. has been developed for the synchronous machines with DC excitation. This scheme uses the structural asymmetries of the field winding. Similar results have also been realized using a rotor-mounted search-coil with very high sensitivity. In this work, an instrument has also been devised to implement fault diagnosis on machines using the computational capabilities of digital signal processors.

Thesis (M.S.)--University of Texas at El Paso, 2005. / Title from title screen. Vita. CD-ROM. Includes bibliographical references. Also available online.

Thesis (M.S.)--Virginia Polytechnic Institute and State University, 1993. / Vita. Abstract. Includes bibliographical references (leaves 82-83). Also available via the Internet.

Thesis (M.S.) -- Worcester Polytechnic Institute. / Keywords: power systems; power transmission; fault location. Includes bibliographical references (leaves 83-84).

In this dissertation, we propose two fault simulators, called HOPE and HOPE2, and an autolllatic test pattern generator (ATPG), called ATHENA, for synchronous and asynchronous sequential circuits. HOPE is a parallel fault simulator for synchronous sequential circuits. In HOPE, a packet of 32 faults is simulated in parallel. Several new heuristics are employed in HOPE to accelerate the parallel fault simulation. The heuristics are 1) a reduction of faults to be simulated in parallel, 2) a new fault injection method called functional fault injection, and J) a combination of static and dynamic fault ordering methods. According to our experiments, HOPE is about 2.2 times, on the average, faster than a competing fault simulator, called PROOFS (1]--[2]. for 16 ISCAS89 benchmark circuits [3]. HOPE2 and ATHENA are a fault simulator and an A TPG for asynchronous sequential circuits, respectively. The key idea employed in HOPE2 and ATHENA is 10 transform an asynchronous sequential circuit into a synchronous sequential circuit through remodeling memory elements. We proposed various modeling techniques which transform any asynchronous sequential circuit into a synChronous sequential circuit. Once an asyncllfonous circuit is transformed into a synchronous circuit, various techniques developed for synchronous sequential circuits are employed in HOPE2 and ATHENA. HOPE2 employs the parallel simulation techniques of HOPE. ATHENA employs the back algorithm [4] for test generation, and the parallel fault simulation teChnique for fault simulation. HOPE2 and ATHENA can manage industrial circuits consisting of latches, flip-flops with set/reset, tristate gates, BUS elements, bi-directional I/O pins, mutiplexers, ROMs and RAMs. OUf experimental results on various industrial circuits show that HOPE2 is about two times faster than a commercial fault simulator, the Verifault fault simulator of Cadence, while requiring much smaller memory size. ATHENA also shows high performance for various industrial circuits. / Ph. D.

The detection and location of faults on power transmission lines is essential to the protection and maintenance of a power system. Most methods of fault detection and location rely on measurements of electrical quantities provided by current and voltage transformers. These transformers can be expensive and require physical contact with the monitored high voltage equipment. In this work, current transformers were replaced by magnetic field sensing coils. Such coils can be located remotely from substations and switching stations and do not require physical contact with the conductors. Rather than observing each individual conductor, the use of the magnetic field sensors allows the monitoring of the transmission line condition using a collective quantity. This study explores the use of the magnetic field sensors as an alternative measurement device for fault detection and location.