This thesis deals with the measure of partial discharge. First of all the work will analyze the phenomenon from a general point of view: it will focus on the causes that imply partial discharge inception in insulating systems, as well as the behavior of devices in presence of partial discharge activity, in case of different insulating systems. Moreover this thesis discusses different measurement methods, especially electrical ones and those described by the technical standards of the sector. The research carried on in this work is focused on the realization of two different kinds of predictive diagnostic systems, which are able to provide information about the imminent failure of a device subjected to partial discharge activity. The two systems have been developed with different purposes: an experimental one and a more traditional one, but with some modifications compared to the state of the art. The first measurement system has been developed in order to be less invasive as possible; it is made up of an electromagnetical sensor mounted directly on the monitored device. The measurement device works without any connection to the power of the monitored system, but it is possible to monitor only few alarm thresholds. It is impossible to detect the nature of defect to the partial discharge activity. With the second measurement system it is possible to measure the amplitude of each partial discharge, and draw the PD Pattern, which is useful to study the defect. It is easier to diagnose the exact nature of the problem with this kind of measurement system, but it needs a connection to the power circuit. Generally the directors of the maintenance of a system prefer less invasive measurement techniques. Avoiding the connection to the power circuit, the diagnostic is cheaper and safer: the failure of a system often starts from its diagnostic circuit. The two measurement systems can be used in a complementary way: the less invasive one will perform a predictive diagnostic. After the detection of partial discharge activity, the device is stopped, and the nature and the severity of the defect will be analyzed by means of a more invasive one. After the optimization of the electromagnetical system and the design of the more traditional one a test campaign has been conducted in laboratory and in field. The electromagnetical system is used and optimized to measure inside a wind turbine, the other one is used to age specimens and to measure transformers.

Design and optimization of partial discharge measurement systems for conducted and irradiated signals

ROSSI, FABIO
2018-05-28

Abstract

This thesis deals with the measure of partial discharge. First of all the work will analyze the phenomenon from a general point of view: it will focus on the causes that imply partial discharge inception in insulating systems, as well as the behavior of devices in presence of partial discharge activity, in case of different insulating systems. Moreover this thesis discusses different measurement methods, especially electrical ones and those described by the technical standards of the sector. The research carried on in this work is focused on the realization of two different kinds of predictive diagnostic systems, which are able to provide information about the imminent failure of a device subjected to partial discharge activity. The two systems have been developed with different purposes: an experimental one and a more traditional one, but with some modifications compared to the state of the art. The first measurement system has been developed in order to be less invasive as possible; it is made up of an electromagnetical sensor mounted directly on the monitored device. The measurement device works without any connection to the power of the monitored system, but it is possible to monitor only few alarm thresholds. It is impossible to detect the nature of defect to the partial discharge activity. With the second measurement system it is possible to measure the amplitude of each partial discharge, and draw the PD Pattern, which is useful to study the defect. It is easier to diagnose the exact nature of the problem with this kind of measurement system, but it needs a connection to the power circuit. Generally the directors of the maintenance of a system prefer less invasive measurement techniques. Avoiding the connection to the power circuit, the diagnostic is cheaper and safer: the failure of a system often starts from its diagnostic circuit. The two measurement systems can be used in a complementary way: the less invasive one will perform a predictive diagnostic. After the detection of partial discharge activity, the device is stopped, and the nature and the severity of the defect will be analyzed by means of a more invasive one. After the optimization of the electromagnetical system and the design of the more traditional one a test campaign has been conducted in laboratory and in field. The electromagnetical system is used and optimized to measure inside a wind turbine, the other one is used to age specimens and to measure transformers.
28-mag-2018
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11567/929103
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