Offshore Wind Blackstart & Restoration: State-of-the-Art Literature Review

As Power Systems decarbonise, Offshore Wind Power Plants (OWPPs) are increasingly considered as replacements for conventional Blackstart units. This work synthesises State-of-the-Art OWPP blackstart capabilities, whose Wind Turbine Generators (WTGs)—upgraded with Grid-Forming (GFM) controls in their Voltage-Source (Power-Electronic) Converters (VSCs)—establish and regulate island voltage and frequency, energise networks, and resynchronise. Traditional Restoration guidelines centre on Synchronous Generators, yet emerging codes expect converter interfaced resources to assume these roles. Electromagnetic Transient (EMT) studies and pilot tests demonstrate that a limited number of GFM WTGs can energise AC cables, transformers, and High-Voltage DC (HVDC) terminals when sequencing, protection, and control are co-designed. From the modelling point of view, this literature-based work pinpoints six research gaps: (1) re-energisation sequencing of the dead system; (2) WTG/OWPP model fidelity and data confidence; (3) low-fault-current and protection coordination; (4) GFM controls suitable for blackstart operations; (5) multi-converter operation across mixed GFM/GFL WTG units plus HVDC/Battery Energy Storage Systems (BESS); and (6) resynchronisation with load pickup and transition to normal operation. The analysis concludes that GFM-controlled OWPPs remain promising yet under-demonstrated, and consolidates fragmented results into guidance and a set of focused, actionable guidelines to help certify OWPPs as reliable blackstart resources.