In the next years, several offshore wind farms will be installed all over Europe. Due to the technologic advantages that voltage-source converters have when compared to other available options, there is a strong possibility that this will be the technology chosen to connect offshore wind farms. Such assumption intensifies the need of studying and simulating the control methods for these systems. Therefore, the purpose of this work is to present and explain all the models that are needed to simulate, with the necessary detail, the electric systems of the offshore wind farms, the high-voltage converters and the DC grid. The control method of the DC system is given and several methods to control the DC grid voltage are presented and compared. This way, it will be possible for several countries connected to the multi-terminal DC grid not only to receive energy from the offshore wind farms, according to desired criteria, but also to trade energy with other nations.