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Title: Switching transients in large offshore wind farms
Author: Mir Ghafourian, Seyed Mohammad sadegh
ISNI:       0000 0004 5356 4379
Awarding Body: University of Manchester
Current Institution: University of Manchester
Date of Award: 2015
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This thesis deals with the analysis of switching transients in large offshore wind farms. Switching transient is of great importance in electrical power systems in general, not least in offshore wind farms. The large area required for an offshore wind farm along with its offshore location results in extensive cable systems with a large number of radial feeders and medium voltage transformers. These transmission systems are very different from traditional onshore networks. Hence, accurate transient analysis is important, as travelling wave reflections can become critical in some reflection points; where aggregate overvoltage may exceed the voltage withstand level of the system components. The rate of rise of overvoltage is a crucial issue to be considered for transformer inter-turn resonances, which leads to high frequency over-voltages. The closing operation of a vacuum circuit breaker during energisation of wind farm networks can cause switching transients which might damage the insulation structure of cables, transformers and turbine generators. The repetitive impact on the systems without remedialaction may cause premature ageing of the above mentioned components, so to minimize the failure risk, the accurate model is essential. One of the contributions of this thesis is in refining a new modelling of the VCB and in the implementation of the new VCB model in the assessment of a specific switching transient event (VCB closing operation in an offshore wind farm). Experimental verification of transient overvoltage phenomena modeling in submarine cable networks is another contribution of this work. Correlation calculation shows that simulations of the high frequency transients with this novel refined model are in a very good agreement of better than 94% in comparison with the measurements taken in an offshore wind farm.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available