Economic limitations of the HVAC transmission system when applied to offshore wind farms

With the onshore wind power potential, practically at the limit in Portugal, it is necessary to explore the offshore potential. The continental plate is very “aggressive”, from a few hundred meters of seashore, the bathymetric, falls hundreds of meters. To overcome this situation and profit the offshore potential, it is necessary to place the wind farms, in deep waters, increasing the maximum of power of the wind power turbines. The traditional HVAC (High Voltage Alternating Current) transmission, in certain circumstances may be limitative when using in submarine cables. The mechanisms of the supply systems in HVAC, in its traditional way (air-lines), are faced with constraints. This kind of subsea infrastructure imposes restrictions, just by the fact that the capacity and inductance parameters are significant, which, when dealing with energy transmission, make “impossible” the power transmission due to its high consumption of reactive power. Also the economic aspects becomes extremely relevant. With the technological evolution of the wind platforms turbines, Portugal intent to increase the power of the offshore wind farms. I this paper with was analyzed, the supply systems in HVAC, when applied to offshore wind farms present limitations. The solution can be the HVDC (High Voltage Direct Current) technology as it reveals to be the most adequate to the energy transmission associated with this offshore wind farms, in certain circumstances. In addition to the technical factors, it was also analyzed the costs associated with this to types supply systems. And some conclusions are presented in order to define a limit between this to systems.