Offshore Electricity Infrastructure in Europe - European Wind Energy ...

Annex c – details on the Methodology and Models
The consortium has therefore decided to develop a
case-independent model, which is an abstract model
that can help to do extensive sensitivity analysis in
an efficient manner. The results are cross-checked
with the case study results from the real model. The
case-independent model uses inputs from both the
infrastructure and power system model. Instead of doing
an optimisation process for each hour of the year,
it aims at approaching the cost-benefit results based
on average values and with simple straightforward
rules. Consequently, it provides an approximate but
robust result that allows quickly assessing whether it
is worth to investigate the case in more detail.
As with the combination of the models of section
C.II and C.III, the costs and benefits are compared
for different designs, where costs and benefits are
defined as:
• Infrastructure costs (depending on cable length
and capacity)
• System benefits = present value of yearly trade
benefits, which are defined as the sum of the product
of hourly price difference between countries
and the hourly remaining capacity for trade (interconnector
capacity not used by wind power)
The model is built in Matlab and focuses on two design
problems, namely the teeing-in of wind farms into
an interconnector between two countries, and the interconnection
of two countries via two offshore wind
farm hubs in between. As inputs, it uses:
• Infrastructure cost tables (varying with distance
and capacity) developed by SEL for:
– individual connection of wind farms
– teeing-in of wind farms
– direct interconnector
– interconnector between hubs
• Market price profiles and the difference between
them for different countries (outcome of the power
system model by SINTEF)
• Time series for the wind power production of a wind
farm (data from Forwind model used)
126
The objective of the case-independent model is to
have concrete design guidelines that are useful for
various stakeholders. To this end, an extensive sensitivity
analysis is done that looks into the impact of the
price difference between countries, to the impact of
cable or wind farm capacities, to the impact of cable
lengths and reduced cable length, and to the direction
of the price difference. The model can vary the following
parameters:
• Average absolute price difference between
countries
• Balance of the price difference between countries
(balanced flow with 50% of price difference to either
country or balanced more towards one of the two
countries)
• Distance between onshore connection points
(cable length direct interconnector)
• Distance between hubs and onshore connection
points
• Distance between hubs (possible reduction in cable
length vs. a direct interconnector)
• Capacity of the wind farm(s)
• Capacity of the cables
OffshoreGrid – Final Report