The North Seas Countries' Offshore Grid Initiative - Initial ... - Benelux

A 1.3 Grid Expansion Approach (Grid Design and grid simulations)
The development of an optimised transmission network to accommodate further market
integration and the integration of the specified offshore wind parks (OWP) - in both their
capacity and planned locations - involves the exploration of various designs of the bulk
transmission network. For this study, the objective is to define plausible radial and
meshed network designs.
The geographical scope of the study area and the consequential scale of the transmission
network that is required to be considered for augmentation are exceptionally large. This,
together with the resulting magnitude of network reinforcement options (choice of
locations, choice of technologies, choices of capacities etc.), and combinations of options
to consider, conspire to make a numerically complex problem for which few systematic or
automated problem-solving tools are readily available.
The decision-making aspect of testing competing reinforcement candidates lends itself to
a optimisation solution. A linear-programming tool has been chosen to support the
process
the line-capacity shortages and the necessary new circuits to relieve those
shortages in the existing transmission networks; and
The combination of network components and technologies that would represent
the plausible network configurations to facilitate further market integration and to
appropriately integrate the proposed OWPs with the existing power systems.
A 1.3.1 Capacity-Based Grid Expansion
The optimisation of power system capacities is done by using Mixed Integer
Programming. An optimisation tool has been used to develop the outline designs for both
the radial and meshed, or integrated, network designs. The tool has been used to perform
other studies in the region [11].
Linear flow estimation is used to simulate the maximum steady state power flow through
the onshore and offshore transmission network. Candidates for new grid links are made
available by national experts to be selected by the optimisation routine in order to meet
the future grid requirements which come from the market studies. The objective is to
minimise the overall production cost, capital cost of new investments (selected from the
large list of candidates) and operational losses while satisfying all the supply and demand
restrictions.
The addition of any new onshore or offshore transmission link to the model will change
the technical and economic performance of all other candidates such that the optimisation
process must consider all possible combinations of candidate reinforcements. The
selection of the optimum candidates is made using the Branch and Bound method. The
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