The forthcoming RfG 2.0 regulation requires Type B to Type D Power Park Modules (PPMs) to comply with Grid Forming (GFM) control capabilities. Although the majority of GFM performance requirements are specified at the Power Generating Unit (PGU) terminals, the electrical network between the GFM PGUs and the Point of Connection (PoC) has a significant influence on how GFM behavior is perceived by the transmission system. In offshore wind applications, this influence is particularly pronounced due to long export cables and multiple transformer stages within the offshore network.

This paper investigates the impact of the offshore wind farm electrical network using analytical time-domain and frequency-domain methods. The analyses focus on quantifying how cables and transformers collectively affect system strength, effective impedance, and the attenuation of GFM characteristics across the wind farm. The analytical findings are further validated through Electromagnetic Transient (EMT) PSCAD simulations using an offshore wind farm example with a vendor specific GFM Wind Turbine Generator (WTG) model.

The results demonstrate that, without careful offshore network design, the intended GFM contribution of inverter-based resources can be significantly weakened, thereby reducing their effectiveness in supporting weak grid scenarios. While the ENTSO-E grid-forming framework specifies indicative impedance limits (e.g., effective impedance within 0.5 pu at the PoC), this work explicitly quantifies the impact of individual offshore network components on GFM performance.