Identification of resonance interactions in offshore-wind farms connected to the main grid by MMC-based HVDC system

The transient stability of an offshore-wind farm connected to the main ac grid by a high-voltage direct current (HVDC) system depends on the control settings of the converters, the grid resonances and the system’s operating conditions. This paper focuses n identifying possible sources of resonance interactions that could endanger the overall stability of this kind of system. For this purpose, the ac-side input admittance/impedance of a full-power converter (FPC) wind turbine and an MMC-based HVDC system are derived and frequency-domain stability analysis tools are used to assess the impact of system and control parameters on stability. The analytical findings are verified through time-domain simulations and recommendations to increase system stability are given accordingly.