Primary Frequency Response from Offshore Wind Farms Connected to HVdc via Diode Rectifiers

Diode rectifiers have been gaining traction as a viable alternative for connecting offshore wind farms (OWFs) to HVdc networks. However, before technical connection requirements compatible with such solutions can be determined, more studies are needed to assess their capabilities to contribute to the secure operation of the networks linked to them. This study assesses the capability of such an OWF to provide support to an onshore ac network by means of primary frequency response (PFR). A semi-aggregated OWF representation is considered in order to examine the dynamics of each grid-forming wind turbine (WT) within a string when providing PFR. Simulation results corroborate that such an OWF can indeed provide PFR, while its grid-forming WTs share the reactive power and keep the offshore frequency and voltages within their normal operating ranges.