Investigating Implications of Offshore Wind Farm Connections Regarding Harmonic Distortion

(GIPs) and offshore Points of Connection (POCs). The objectives are to quantify incremental harmonic voltage distortion (IHVDL), distinguish the contributions of background distortion versus wind turbine generator (WTG) emissions, and design practical passive filters that remain effective under changing project data, contingencies, and system strength.

The methodology proceeds in three steps plus sensitivities. First, frequency sweeps are used to evaluate the frequency‑dependent network equivalent (FDNE) at each OWF’s onshore GIP across local contingencies in Winter Peak (the highest demand snapshot) and Summer Valley

(the lowest demand snapshot) cases. The focus was on the 2nd to 40th harmonics. Second, reduced equivalent models are built to compute IHVDL at the GIP and harmonic distortion at offshore 220 kV/66 kV POCs, iterating filter designs against EirGrid incremental limits and IEC 61000‑3‑6 planning levels. Third, the interaction studies analysed all integrated OWFs to the EirGrid transmission system model with modified background distortion and the compliance at all GIPs were monitored. Sensitivity analyses were performed to understand the impact of array‑cable parameters, WTG emission spectra, and prospective projects in the region.

Overall, it was observed that a coordinated passive filtering at onshore compensation compounds with selective offshore measures can deliver compliance for the OWFs. Persistent low‑order issues (5th, 7th, 11th etc.) sometimes necessitate WTG‑side emission tuning. Given iterative design cycles and evolving manufacturer/network data, continuous monitoring, active resonance management, and potential future grid strengthening are essential to ensure robust, compliant integration as Ireland’s generation mix transitions.