Step-wise stochastic optimisation of transmission grid for offshore wind farm clusters

Harald G Svendsen 1, Martin Kristiansen2, Magnus Korpås2
1SINTEF Energy Research, Trondheim, Norway, 2NTNU, Trondheim, Norway


A lot of wind farms and clusters of wind farms in will be built in the North Sea. As distances from shore increase, the relative cost of the transmission system becomes more important. To obtain the lowest possible cost of energy, it is key to design the offshore transmission grid in an economic way, that takes into account the variable nature of production and demand, cost of other generators, and the possibility of sharing infrastructure

A new grid layout optimisation method that addresses this issue will be presented. It is based on a tool (Net-Op) previously developed, but extended to also take into account the step-wise nature of investment decisicions and parameter uncertainties, e.g. regarding the extent of other grid investments, cost developments etc.

The presentation will present the approach and results from a case study focussing on the Doggerbank cluster.


The grid optimisation is a mixed-integer linear programming problem with stochastic parameters. Variability in power demand/prices and wind power availability is represented by time-series, and the optimisation is done for a sample of operating conditions. The objective is to minimise the socio-economic cost, i.e. the sum of generation cost and investment costs. Uncertain parameters may be the capacity of a wind farm, capacity of an HVDC interconnector or similar. The approach is demonstrated and tested on a realistic Dogger bank case study.


The main result is the demonstration of a new, open and useful tool to explore and optimise offshore grid connection alternatives for offshroe wind farm clusters. Furthermore, detailed results from a Dogger bank case study will be provided, both the underlying assumptions and the optimal solution. Sensitivity of the results to key parameters, such as infrastructure cost will be assessed and presented.

The presentation will present ongoing work that will be completed in February 2017, conducted as part of the EU funded project IRPWind.



The paper demonstrates an improved version for offshore grid layout design, that can benefit the wind industry and other stakeholders by providing good offshore grid layout alternatives in the early planning phase of wind farm clusters.

The new open-source tool presented and demonstrated in this presentation can be taken into use by anyone interested and support planning work and decision making.



Delegates will be introduced to an optimisation approach and open-source tool suitable for offshore wind farm clusters. It enables developers, strategic planners and scientists to assess grid options and identify robust grid layouts in early phase planning.