Overview of Black Start Provision by Offshore Wind Farms

Thanks to the solid standards and principles of design and restoration planning after a blackout, power systems in developed economies generally show a high level of resiliency. Nevertheless, this power system restoration practice strongly relies on conventional power plants, e.g. large thermal power plants. As future global goals aim at reducing the use of fossil fuels and lowering carbon-dioxide emissions, conventional power plants are often taken out of operation. These are characterised by slow start-up times and considerable use of fossil fuels. In this context, large offshore wind farms (OWFs) show potential as renewable-based black start (BS) service providers. These can be equipped with a self-starter, e.g. synchronous generators or innovative power-electronic-based converters, such as battery energy storage systems (BESSs) and/or grid-forming wind turbines in order to BS the system. Additionally, state-of-the-art complementary devices such as STATCOMs or synchronous condensers can help with dynamic regulation and support the OWF both in island operation and BS. In this paper, an overview of different system configurations for OWF BS is presented. Firstly, the requirements for BS from non-conventional power plants are outlined. Afterwards, the challenges faced by OWFs to fulfil these requirements are identified. Finally, different solutions for system configuration to equip OWFs for BS are proposed.