Modeling and Control of an Offshore Wind Farm connected to Main Grid with High Voltage Direct Current Transmission

Offshorewind farms inherently need alternating current (AC) grid connection withundersea cables. However, this requires reactive power compensation, which iscostly and not practical. Moreover, it threads the stability of the system. Forthese reasons, high voltage direct current (HVDC) transmission is a promisingsolution since no reactive power is needed. Furthermore, the DC power flowbetween offshore and onshore locations as well as the reactive power at eitherside can easily be controlled by voltage source converters (VSCs). In thispaper, the modeling and control of an offshore wind farm connected to themainland grid power with HVDC transmission is proposed. A control strategy isproposed to control active and reactive power at the offshore wind farmconverter and DC voltage at the onshore converter. The overall system,including wind farm, offshore and onshore converters, HVDC transmission, and ACgrid side, were tested and verified in a simulation environment. The designedcontrol systems of the VSCs were tested by various case studies.