Book excerpt: Nowadays, High Voltage Direct Current (HVDC) systems based on Voltage Source Converters (VSC) are being installed for integrating the energy of individual offshore wind power plants to the main land AC grid. Moreover, as the number of offshore wind power plants is increasing, the interconnection of the different links in a multi-terminal grid, to increase the system exibility, becomes interesting. In this work, the different elements of a multi-terminal VSC-HVDC grid are modelled, VSC converters controllers are designed and the complete system is simulated employing Matlab Simulink to analyse the operation in different scenarios.