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1 Published by and copyright 2011: Siemens AG Energy Sector Freyeslebenstrasse Erlangen, Germany Siemens AG Energy Sector Power Transmission Division Power Transmission Solutions Freyeslebenstrasse Erlangen, Germany For more information, please contact our Customer Support Center. Phone: Fax: (Charges depending on provider) support.energy@siemens.com Power Transmission Division Order No. E50001-G610-A122-V1-4A00 Printed in Germany Dispo 30003, c4bs No fb 3986 XXX WS 0711X.X Printed on elementary chlorine-free bleached paper. All rights reserved. Trademarks mentioned in this document are the property of Siemens AG, its affiliates, or their respective owners. Subject to change without prior notice. The information in this document contains general descriptions of the technical options available, which may not apply in all cases. The required technical options should therefore be specified in the contract.

2 The Offshore Way WIPOS Wind power offshore substation Answers for energy.

3 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. 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 2

4 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 assembly 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. 5

5 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. 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. 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. 3

6 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. 4