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Siemens AG
Energy Sector
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Siemens AG
Energy Sector
Power Transmission Division
Power Transmission Solutions
Freyeslebenstrasse 1
91058 Erlangen, Germany
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The required technical options should therefore
be specified in the contract.
www.siemens.com/energy/wipos
The Offshore Way
WIPOS – Wind power offshore substation
Answers for energy.
WIPOS – configuration flexibility
to meet every challenge
With the new wind power offshore substation WIPOS®, Siemens has created a
benchmark for the design, engineering,
and installation of offshore wind-farm
substations.
In the offshore wind industry, the word
“platform” traditionally refers to two construction entities: the “topside”, where all
the high-voltage, medium-voltage, and
operational equipment is installed, and
the “foundation” entity, which serves as
the base for the topside.
In WIPOS, Siemens offers optimized
designs for both entities by combining
the expertise of electrical, onshore, offshore, maritime, and shipyard experts.
WIPOS serves as an interface between the
wind turbines and the mainland, through
which power harvested from wind is bundled and then passes through the export
cables to reach the point of connection
onshore.
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The topside comprises a multi-deck construction where all electro-technical
equipment including the AC/DC essentials, low/medium/high voltage equipment, and DC converters are installed to
create an efficient offshore substation.
The substation can be used to transmit
either AC or DC power depending on various factors, including the distance to the
point of connection onshore.
Siemens offers a family of WIPOS designs
with the flexibility to meet a variety of
offshore weather, tide, and seabed conditions with three main configurations:
◾◾ WIPOS self-lifting solution
◾◾ WIPOS topside solution (topside/jacket)
◾◾ WIPOS floating solution
WIPOS going offshore
◾◾ As a technology manufacturer driven by innovation
and possessed of a high degree of in-house expertise,
Siemens is able to offer the optimized technologies that
best fit the WIPOS® solution.
◾◾ Siemens’ ability to manage complex interfaces (described in the sequential process below), manage a
project schedule with robust processes, and seamless
project management are fundamental in providing an
integrated solution with the requisite performance
guarantees demanded by our clients – for example, grid
code compliance.
◾◾ Siemens is also able to add value by proactively managing the supply chain throughout the project’s lifecycle –
including major subcontracts – from fabrication to installation and transportation.
◾◾ Siemens’ internal design and project management efficiency and expertise are essential for ensuring value for
the customer and managing risk.
◾◾ Once a design concept has been generated, a WIPOS solution will go through a sequential process from
start to realization. The process is generic and applies to
all WIPOS configurations, ensuring consistency and reliability while also offering flexibility.
◾◾ Fabrication takes place in yard facilities equipped with
the heavy-duty machinery and cranes necessary to cut
steel and construct the foundation and the topside. The
topside itself is built in sections: each section is prefabricated and transported by trailers and cranes for assem-
bly and coating. During structure assembly, installation
of equipment on the platform is taking place in parallel.
◾◾ Load-out takes place only after fabrication is complete
and all equipment has been installed and commissioned. There are various methods, dependent primarily
on the facilities available, the conceptual design, and
the load-out weight of the substation. For example, a
topside/jacket configuration can use either a crane to
lift and transport or a multi-wheeled trailer, usually positioned under the platform. A self-installing configuration can use the aforementioned methods, or it can
even be floated out if the yard has an adequate drydock facility.
◾◾ Transport of the foundation and topside begins when
both construction entities are fabricated, loaded out,
and ready to be installed. Transportation time is determined by design, environment, and weather conditions.
As a result, methods of transport may include large
barges with high transport capacity for a typical jacket/
topside solution, or tugboats with high pulling capability for self-lifting solutions.
◾◾ The foundation is pre-installed prior to the arrival of the
topside by positioning and lowering it onto the seabed
in a controlled manner until it reaches the specified location, in accordance with the final seabed survey. The
topside is then transported to its final position and fixed
to the foundation. Installation methods will also vary
from one configuration to another depending on,
among other things, crane vessel size variations.
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WIPOS – self-lifting solution
As the name implies, this platform structure lifts itself.
Known for its versatility, this solution
offers the opportunity for self installation
and eliminates the need for a heavy-lift
vessel as well as other associated risks.
Installation and transport costs will be
reduced given its inherent ability to float
and self-install.
The self-lifting solution consists of the
following core components:
◾◾ Topside including legs: the topside consists of a rectangular pontoon with customized internal walls and decks to suit
the type and configuration of equipment required. The legs are an integral
part of the topside; they are immersed
and then connected to the substructure
base frame, allowing self-jacking/
installing.
◾◾ Depending on the project requirements, a cable access tower can be
incorporated. This serves not only as a
protective casing for the J-tubes and
medium/high voltage import/export
cables to and from the platform, but
also facilitates pre-installation of these
cables before the installation of the
topside.
◾◾ Helideck and accommodation/control
building structure: if requested, a helicopter landing deck can be installed on
the aft of the pontoon on a tubular
supporting frame. The helideck is designed to meet aviation regulations
with respect to approach directions and
obstacle limitations.
◾◾ Substructure base frame: the base
frame is the foundation of the platform
and serves as an interface with the
piles, which are driven into the seabed
and connect the platform legs.
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WIPOS – topside and jacket solution
This flexible tried-and-tested solution is
widely used for topsides that are either
too heavy for monopile foundations (for
example, two step up transformers or
more) and/or where there are many subsea cables that will be collected at the
substation. This solution, which consists
of a jacket substructure and a topside, is
also appropriate where there are variable
seabed conditions. The following main
components and configurations are
available:
Topside:
The topside structure may accommodate
the bulk of the high-voltage electrical
equipment as well as personnel and
equipment support facilities. It is available in two basic configurations:
◾◾ Trussed construction: this solution consists of decks linked by steel trusses,
which give strength to the structure.
◾◾ Plated construction: this solution uses
the walls and deck floors to give
strength to the overall structure.
Jacket substructure:
The jacket substructure will include tubular legs and braces to provide structural
strength. There are also two basic configurations of the jacket substructure:
◾◾ Stand-alone jacket: the preferred solution when the project’s schedule dictates that the installation of the topside
will follow shortly after the jacket installation or, for example, when the
jacket can be installed by the Wind Turbine Generator (WTG) installation vessel, therefore avoiding two mobilizations of a heavy-lift vessel.
◾◾ Jacket including a cable deck: the preferred solution when the project’s
schedule requires early installation of
cables prior to the later delivery of the
topside.
It is possible to equip all these configurations with a helicopter landing deck,
which is designed to meet required aviation regulations with respect to approach
directions and obstacle limitations.
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