dc.contributor.advisor Høidalen, Hans Kristian nb_NO dc.contributor.advisor D'Arco, Salvatore nb_NO dc.contributor.author Martinsen, Erik nb_NO dc.date.accessioned 2014-12-19T13:56:39Z dc.date.available 2014-12-19T13:56:39Z dc.date.created 2014-11-13 nb_NO dc.date.issued 2014 nb_NO dc.identifier 762902 nb_NO dc.identifier ntnudaim:11831 nb_NO dc.identifier.uri http://hdl.handle.net/11250/258064 dc.description.abstract In this thesis work, different proposed methods for detecting and locating short circuit faults in Multi Terminal HVDC grids have been evaluated by implemenation and transient simulations in PSCAD. The research has been limited to cable based systems. HVDC grids have seen increasing interest in recent years, but have yet to be fully realised. Suitable converter technology was introduced in 1997 and has been further developed since, while switches able to interrupt large DC currents were introduced in June 2013. One of the major issues left is fault localisation. Due to the low impedance in HVDC cable systems, fault currents rise to severe magnitudes system wide in a matter of a few milliseconds. This may cause damage to the converter diodes if not dealt with quickly.In order to obtain a better understanding of the fault propagation, research into the subject is presented. It is found that the capacitors in the converters is a main source of large fault currents, and fast fault detection is essential for protection of converter components. Time between first detection of fault until current interruption should be within a few milliseconds. Different methods have been proposed for localisation of faults in recent years. These are presented together with traditional fault localisation methods, and briefly discussed with the intent of deciding which to implement and evaluate in PSCAD.Protection based on current derivative and wavelet transformation, as well as travelling wave protection is chosen and implemented in a three converter VSC system. Different fault types are applied at various locations with varying system capacitance and up to 16 $Omega$ fault impedance. The results indicate that none of the three methods are able to detect and locate all impedance faults on their own. The travelling wave protection is suitable for short lines, but fails when exposed to high fault impedances and distances. By using derivative polarity to determine direction of fault and wavelet magnitude to determine distance, faults are successfully located in a high capacitance system within a respectable time. It is concluded that all the three tested methods should be considered for implementation when designing a future HVDC protection system. nb_NO dc.language eng nb_NO dc.publisher Institutt for elkraftteknikk nb_NO dc.subject ntnudaim:11831 no_NO dc.subject MTENERG energi og miljø no_NO dc.subject Elektrisk energiteknikk no_NO dc.title Evaluation of Methods for Detecting and Locating Faults in HVDC Grids nb_NO dc.type Master thesis nb_NO dc.source.pagenumber 148 nb_NO dc.contributor.department Norges teknisk-naturvitenskapelige universitet, Fakultet for informasjonsteknologi, matematikk og elektroteknikk, Institutt for elkraftteknikk nb_NO
﻿