Soft Energization and Blackout Recovery of Offshore Wind Farm Export System

Abstract: Power generation of the future will be dominated by renewable energy sources. This is a positive trend as society aims to improve sustainability, energy security, and reduce CO2 emissions. This progress however bears challenges for the power systems of the future. One area of particular concern is the blackstart recovery capability of the power systems following blackout events that disrupt electricity supply, as traditional blackstart suppliers have originated from unsustainable power sources. As new sustainable technologies are explored to fill the void, offshore wind power has been identified as a potential suitor to address future blackstart deficiencies. However, following a blackout event that leaves an offshore wind farm isolated, the current technology does not allow for start-up of the wind farm in an islanded mode without assistance from the onshore grid. Hence, a STATCOM with active power storage, known as an ES-STATCOM, is the proposed solution to energize the offshore wind farm to operate in an islanded mode, in preparation for assisting the onshore grid with blackstart. An EMT model and simulation of an ES-STATCOM with grid forming control capabilities and the surrounding offshore wind farm export system were developed in this thesis to assess the viability of the STATCOM solution in energization. The results are promising and show that the ES-STATCOM is in fact able to energize the offshore system to a stable voltage, while avoiding high order harmonics and large overvoltages that have the potential to cause damage to expensive subsea power system components. Ultimately, this thesis serves as a proof-of-concept for blackstart technology, providing useful insights towards the maturity of offshore wind-based blackstart providers of the future.