TY - THES
TI - 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
AU - Allgot, K
AB - This thesis investigates the use of low frequency alternating current (LFAC) for the long-distance 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 offshore cable.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.
DA - 2016/06//
PY - 2016
SP - 1
EP - 113
PB - Norwegian University of Science and Technology (NTNU)
UR - https://ntnuopen.ntnu.no/ntnu-xmlui/handle/11250/2615981
LA - English
M3 - Master's Thesis
KW - Wind Energy
KW - Fixed Offshore Wind
KW - EMF
KW - Physical Environment
ER -