Multistage grid investments incorporating uncertainty in offshore wind development

Representation of uncertainty in transmission expansion planning (TEP) models has become increasingly important as many power systems are exposed to significant technological changes induced by top-down climate and energy targets. The objective with this paper is to incorporate uncertainty regarding future offshore wind deployment and allow two investment stages for grid expansion, where the second stage provides valuable flexibility for a system planner. A stochastic two-stage mixed-integer linear program is used for this purpose applied to a case study of the North Sea Offshore Grid (NSOG). With the given data and assumptions, we show that the system planner can gain maximum €1.72 bn (0.40 %) in terms of cost savings under perfect information about the wind deployment. The expected cost savings for a more forward-looking system planner using a stochastic program is €22.30 m (0.0052 %), in comparison with the best deterministic approach. Moreover, we show that if the planner can postpone its investment decision with five years an expected cost saving of €22.41 m would arise.