A large number of offshore wind farms and interconnectors are expected to be constructed in the North Sea region over the coming decades, creating substantial opportunities for the deployment of integrated network solutions. Creating interconnected offshore grids that combine cross-border links and connections of offshore plants to shore offers multiple economic and environmental advantages for Europe's energy system. However, despite the growing consensus among key stakeholders that integrated solutions can be more beneficial than traditional radial connection practices, no such projects have been deployed yet. In this paper we quantify costs and benefits of integrated projects and investigate to which extent the cost-benefit sharing mechanism between participating countries can impede or encourage the development of integrated projects. Three concrete interconnection case studies in the North Sea area are analyzed in detail using a national-level power system model. Model outputs are used to compute the net benefit of all involved stakeholders under different allocation schemes. Given the asymmetric distribution of costs and benefits, we recommend to consistently apply the Positive Net Benefit Differential mechanism as a starting point for negotiations on the financial closure of investments in integrated offshore infrastructure.

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Abstract:The high pollution coming from the use of gas turbines in oil and gas (O&G) platforms is calling for more sustainable solutions. One of those is to use wind turbines (WT) to supply power to the water injection systems (WIS) of offshore O&G installations and explore the potential of smart energy management in providing more efficient and green solutions to the O&G sector. The effect of WT integration into the local power system and the coordination with the local gas turbines, need to be carefully analysed since the natural intermittency of the wind resource can jeopardize the stability and efficiency of the offshore grid. In general, the existence of flexible loads interfaced by variable speed drives (VSD), such as water injection systems, can help overcome some of the challenges related to wind intermittency and local rotor angle stability: suitable control of such non-essential loads and load segregation can be implemented to reduce the effect of wind power fluctuations, balance power generation and consumption and contribute to maintaining the optimal efficiency of the gas turbine adjusting its loading conditions. The basic assumption is that the WIS can follow the generation available from the wind turbines. The assumption is reasonable since WISs do not require a fixed injection rate. This work will investigate the system dynamics in the event of short-term wind-induced power fluctuations, analysing the evolution of electrical variables, such as active power and generator rotor speed/frequency, under different operating conditions, to specifically evaluate the possible arise of low-frequency oscillations. The impact of an adequate WIS load control to counteract wind variations and increase the system damping is also further explored. Moreover, in order to prevent the event of critical rotor oscillations in the gas turbine and other directly-connected rotating machines due to the WT dynamics, an algorithm for system damping estimation is proposed and its performance studied in the selected test cases.

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