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Title: Partial discharge diagnostics in medium voltage cables
Author: Mohamed, Faisal Peer
Awarding Body: University of Strathclyde
Current Institution: University of Strathclyde
Date of Award: 2013
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Most of the high voltage cables installed in the United Kingdom for power transmission and distribution are approaching the end of their designed life. This is likely to lead to an increased prevalence of circuit faults resulting directly from insulation degradation and breakdown due to ageing. This will lead to customer interruption and regulatory penalties. A program for the wholesale replacement of vast cable networks is impracticable, not economically viable and most likely unnecessary. A more pragmatic and affordable approach to extending the life time of these ageing assets, incorporating targeted cable replacement, may be achieved through the use ofcondition based maintenance strategies utilizing online partial discharge monitoring technologies. Partial discharges (PD) are the early symptoms of insulation degradation that can ultimately lead to complete breakdown of the insulation system. Presented in this thesis are novel contributions to the area of online PD diagnostics for underground medium voltage cables. The work encompasses various issues with installation of PD sensors in cable networks, data acquisition procedures and signal processing techniques for post processing of PD data. A novel approach of using power frequency current transformer for detecting PD is proposed. This approach is validated using laboratory tests and on-site trials using the PD monitoring hardware developed. PD source location using double ended method is widely accepted due to theaccuracy in discharge site location compare to single ended approach. However, this method is not widely used due to its complex system design, time synchronization and communication requirement between measurement units at both ends of the cable network. In this thesis, double ended PD source location system using a novel time based triggering logic is implemented in field programmable gate arrays with GPS. System design, laboratory results and on-site trials are presented. Denoising of PD signals using second generation wavelet transform are comparatively faster than classical wavelet based techniques. This second generation wavelet transform using kurtosis based thresholding is developed and tested using synthetic and on-site data. A PD signal interpretation algorithm is applied to analyse the data acquired from the 11kV PILC cable network from 33/11kV substation using the system developed.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available