Offshore VSC-HVDC Networks: Impact on Transient Stability of AC Transmission Systems

The transition towards a sustainable society calls for the massive deployment of renewable energy sources such as large wind parks located far offshore. High-voltage direct current transmission based on voltage sourced converter technology (VSC-HVDC) offers a wide range of technological benefits that foster the grid integration of offshore wind parks. Coupling AC and HVDC grids comes with significant challenges. Control and system functions, which were formerly separated, interact, especially during faults in the transmission system. Classical (transient stability) modelling and simulation does not suffice and must be made ready for VSC-HVDC.

This Ph.D. thesis answers two questions to master these challenges. First, what is the impact of the operation and control of a, possibly multi-terminal, offshore grid based on VSC-HVDC on the transient stability of the onshore power system? Second, how can we model and simulate these impacts while maintaining the desired simulation accuracy and speed? The results of this thesis facilitate fast and accurate assessment of stability impacts of large transmission systems with a significant proportion of converter-interfaced generation.