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Tesis:

New developments in online diagnostics and protection of brushless synchronous machines

  • Autor: MAHTANI MAHTANI, Kumar Vijay

  • Título: New developments in online diagnostics and protection of brushless synchronous machines

  • Fecha: 2023

  • Materia:

  • Escuela: E.T.S. DE INGENIEROS INDUSTRIALES

  • Departamentos: AUTOMATICA, INGENIERIA ELECTRICA Y ELECTRONICA E INFORMATICA INDUSTRIAL

  • Acceso electrónico: https://oa.upm.es/76885/

  • Director/a 1º: FERNÁNDEZ BEITES, Luis

  • Resumen: This thesis deals with the detection and protection of brushless synchronous machines. The detection and protection of brushless synchronous machines is tackled through two different approaches. On the one hand, a theoretical approach is developed, and other hand, an artificial intelligence-based approach is developed. Because the lack of available measurements makes the detection of electrical faults in the rotating elements of brushless synchronous machines particularly challenging, this thesis concentrates on these, but its developments can be extended to other faults and other fault locations. The theoretical approach built upon the comparison between the theoretical and the measured exciter field currents. The theoretical exciter field current is computed from the main machine output magnitudes at any monitored operating point by means of a theoretical healthy machine model that links the main machine with the exciter. The theoretical principles and the healthy condition model have been verified. Afterwards, this estimation has been applied to detect interturn faults at the field winding of the main machine with different severity levels and rotating rectifier faults. This work has been carried out through computer simulations and through experimental tests. The artificial intelligence-based approach is based on artificial neural networks algorithms, in order to predict the exciter field current in brushless synchronous machines from the machine output measurements, with the aim of detecting faults and protecting the machine. For this purpose, it is necessary the use of numerous healthy operational data to train the algorithm. Afterwards, the estimated excitation current is compared with the real measured excitation current. The type of fault, and given the case the severity level, are obtained from this comparison. The proposed algorithm has been built and assessed through experimental tests. Both approaches represent novel and fast methods fault detection methods, which are characterized because they are online and non-intrusive, and also because their industrial application is straightforward as they are based on inputs that are regularly available in industry without requiring any additional equipment. Additionally, two other developments are proposed and applies to some specific elements of brushless synchronous machines, located upstream (field winding of the exciter) and downstream (main machine stator) of the rotating elements. On the one hand, although the provision of excitation power is a critical aspect to the operation of brushless synchronous machines, there is no extensive technical development in specific online diagnosis and protection methods for the exciter field winding. In this thesis, a temperature-based approach is proposed and applied, in order to provide protection to the field winding of the exciter, which can be extendable to any static winding fed with direct current. The proposed method is based on the comparison of the measured winding resistance and winding temperature, at each operating point, with a healthy condition temperature-resistance characteristic obtained beforehand. The applicability of the method has been verified through experimental tests. On the other hand, it is a fact that stator ground fault protection functions for synchronous generators have usually a fixed setting for rated conditions. In case of variable speed and voltage operation, the protection does not cover all the operation range of the machine. In addition, unwanted tripping may occur due to incorrect filtering of the third harmonic. In this thesis, an auto-adaptative approach to the stator ground protection function is presented, specially conceived for the operation of synchronous machines at variable voltage and frequency. The applicability of the method has been verified through computer simulations and experimental tests.