|dc.contributor.advisor||Sanchez Acevedo, Santiago||
|dc.description.abstract||This thesis investigates the use of low frequency alternating current (LFAC) for the longdistance
transmission of the power extracted from offshore wind farms. It is based on the
measurement of power flow in different nodes in the system simulating an offshore wind
farm being built outside the coast of Denmark, Horns Rev 3 (HR3) . The results for
scenarios simulating different lengths of the offshore cable and the operating frequency
of the system are compared. Reactive power compensation is used to improve the power
flow of the system and to counteract the reactive current from the capacitance in the long
Power flow, voltage- and current limitations of the offshore cable, and varying the reactive
power compensation in the different nodes are used to assess if the different scenarios
described are feasible or not. Considerations related to size and operation at reduced
frequency on the different power system components are mentioned and discussed briefly.
The thesis does not include any detailed analysis with regards to a possible increase in
cost for the different components operating at reduced frequency.
The thesis concludes that the use of LFAC gives reductions regarding power losses, improving
the power system efficiency. For the real case of HR3, using LFAC excludes
the need for reactive power compensation. The thesis also proves that it is possible to
transmit substantial amounts of power over longer distances than any other AC-cable in
operation today. It is proved that using LFAC and reactive power compensation from
shore, it is possible to transmit over 370 MW to the grid with an overall efficiency of
more than 93 %, at a distance of 200 km using a 220 kV offshore cable. Including reactive
power compensation from the offshore end of the cable, the distance can be increased
to 300 km, delivering over 370 MW of power to the grid with an overall efficiency of 91 %.
However, the weight and size of LFAC transformers are considerably higher than the
equivalent 50-Hz components, with up to 2.7 times the weight, this would be a challenge
for the construction of the offshore substation transformers.
Beyond the scope of this thesis further investigations are needed regarding costs for the
different components of the system, as this is not included.||en
|dc.subject||Energi og miljø, Elektrisk energiomforming||en
|dc.title||Low Frequency Alternating Current (LFAC) Transmission Systems for Offshore Wind Farms - Case Studies on the Use of LFAC, Based on Horns Rev 3 Offshore Wind Farm||en
|dc.contributor.department||Norges teknisk-naturvitenskapelige universitet, Fakultet for informasjonsteknologi og elektroteknikk,Institutt for elkraftteknikk||nb_NO