The document summarizes the design of a substation for the Anholt Offshore Wind Farm, one of the largest offshore wind farms in the world. Ramboll designed a substation that will collect electricity from 111 wind turbines with a total capacity of 400 MW, enough to power 400,000 households. The substation design included both a steel jacket foundation and a gravity base structure combined with a steel topside. The steel jacket was initially selected but the client later chose the gravity base structure hybrid design.

1. SUBSTATION DESIGN FOR
ANHOLT OFFSHORE WIND FARM
Complete substation design for one of the world's
largest offshore wind farms which will produce
electricity to 400,000 households
A substation is the one of the core offshore wind farms when it is in The planned location of the wind
elements in the electrical grid of the operation in 2013. farm in an area with very difficult
wind farm. It collects the power seabed conditions, risk of ice loads
production from the wind turbines The 400 MW wind farm will during winter and heavy ship traffic
and transmits the energy to the produce energy equivalent to the have been important factors in the
land-based power transmission grid annual energy consumption of design process.
through submarine cables. 400,000 households, or 4%
of Denmark's total power
There are many shared technical consumption. 111 wind turbines will Two design proposals
details in the design of an offshore produce the energy. The substructure design included
substation and traditional both detailed design of a steel
offshore facility platforms. At The substation and shore cable are jacket solution as well as tender
Ramboll we have transferred our operated by the Danish energy design of a combined concrete
experience in offshore provider Energinet.dk which is GBS/Steel structure (GBS = Gravity
structures from the past 30 years to owned by the Ministry of Energy Based Structure).
become among the market leaders and Climate. The state-owned
in the design of substations for energy company DONG Energy The steel jacket solution was initially
offshore wind farms. owns and operates the wind farm. selected by the client as being the
One substation - electricity to Evaluation of scenarios
400,000 households Ramboll headed the detailed design
One of Ramboll's most recent major of the substation platform,
substation projects is the Anholt including substructure and
CONTACT
Offshore Wind Farm, located 22 km complete topside design. In the Peter Busch Nielsen
off the coast of the island Anholt in design process many different Senior Project Manager, Structures
Denmark. The wind farm will scenarios have been evaluated.
Tel +45 5161 7238
become one of the world's largest
pbn@ramboll.com
RAMBOLL GROUP A/S

2. DESIGN IN ACCORDANCE WITH NEW STANDARDS
The Anholt Offshore Wind Farm substation is one of the renewable energy projects.
first offshore substations to be designed according to the
DNV-OS-J201 standard for Offshore Substations for Wind The new standard will become one of the future standard
Farms. used for European offshore wind farms.
The standard describes the basis for safe design, layout
and operation of offshore wind farms. It is developed to
provide a common set of safety requirements for all
platforms associated with offshore wind farms and other
preferred solution. However, prior to enclosed modules where the The analysis included siting of the
tendering the fabrication contract auxiliary equipment is placed. farm and proposals for possible
of the platform, the client chose to alternative sites, outline foundation
include a tender design by Ramboll The topside structure is divided into design, decommissioning of
of a GBS solution combining the several platform deck levels, structures and constructional and
installation benefits of a floating including a helideck. The operational risk analysis with
concrete structure with that of a structure carries equipment for respect to shipping traffic.
steel structure on top. high-voltage transmission and
distribution and other facilities such In addition, Ramboll also performed
as emergency generator, batteries environmental assessment of the
Fit-for-purpose substation and panels for wind turbine control establishment of a sea cable to the
The fit-for-purpose substation is etc. island of Anholt from the wind farm.
designed with due consideration to
the wishes and requirements laid The substation will transfer energy
out by Energinet.dk as to from the 33kV radial cables of the Ship collision analysis
serviceability, accessibility and the wind turbines, transform the energy In order to state the optimal
operation of the platform over the and export it onshore via a 220 kV location for the wind farm, the risk
expected lifetime of 25 years. The cable where it will be connected to of ship collision was essential to
substation is fully optimised in the national grid. evaluate. Ramboll assisted with
space and weight dimensions. analysing the risk to the general
ship traffic from the ship traffic
Site development and related to the construction of the
Essence of the transformer Environmental Impact Assessment Anholt Offshore Wind Farm.
platform Ramboll has also performed site
The Anholt topside consists of a development and full-scale
central area where the three main Environmental Impact Assessment
transformers and 220 kV GIS (EIA) on the Anholt Offshore Wind
switchgear are located, and Farm project.
LEFT
The substructure
design initially
included a detail
design of a steel jacket
with traditional driven
piles as foundation.
RIGHT
The concrete GBS/
Steel structure
combines the
installation benefits of
a floating concrete
structure with that of a
steel structure on top.