Norway as one of the leading countries in the oil and gas and (floating) offshorewind energy sectors, plans to reduce its carbon emission according to theEuropean commission strategy to become carbon-neutral by 2050. One of theconsiderable contributors to the carbon emission in Norway are oil and gas platforms.Supplying these platforms through offshore wind can accelerate realizingcarbon-neutrality.
A well-built grid can withstand a contingency event and have an acceptablerate of change of frequency due to high inertial characteristics. The reduction ofthe grid inertia is one of the main issues with the paced integration of renewableenergy sources into the electricity grid and replacing the conventional generators.To overcome this issue, multiple mathematical methods have been developed toensure grid stability. These methods are based on an additional energy source tohelp the system stability throughout the event of a contingency.In this project, a few of the methods to provide virtual inertia for renewableenergy sources are reviewed and compared against each other. Based on the ideasinspired by these methods, an algorithm is proposed to assist the inertial responseof the grid of oil and gas platforms.
The proposed algorithm is implemented on a voltage source inverter that extractsenergy from energy storage and injects it into the grid of the platform alongsidegas and wind turbines. The method is validated by a step-change in the loadof the platform and the interactions of the grid components are presented. Comparedto a scenario in which there is no inertial support provided, the proposedmethod proves operational in reducing the rate of change of frequency and therefore,stabilizing the grid during the contingency.
Key words: Electrification of oil and gas platforms, Offshore wind turbine,Virtual inertia, vector control of converter, Back to back converter control, DFIG,gas turbine, Energy storage