Offshore Substations (topside and substructure)

An offshore substation is a key component of offshore wind farms, enabling the conversion and transmission of wind energy to the onshore power grid. It consists of a platform and support structure that are specially designed to operate in extreme offshore conditions. Designing such a station requires advanced engineering expertise and consideration of many factors, such as wind power, waves and corrosion. Every step of the design must be carefully analyzed and tested to ensure maximum performance and safety. The supporting structure, made of steel, must be able to withstand sea salt and continuous dynamic loads. The platform on which the power equipment is placed is designed to minimize the risk of failure and facilitate access to the equipment.

Modern technologies make it possible to create substations capable of handling multiple wind turbines simultaneously, increasing the efficiency of the entire farm. Designing an offshore substation is a complex process that requires the close cooperation of many specialists. The final design must meet all safety standards and be tailored to the individual needs of the wind farm.

The supply of one OSS for Baltyk 2 (topside and substructure) and one OSS for Baltyk 3 (topside and substructure). Each OSS has a capacity of 720 MW.

The OSS EPC scope of work includes the following main activities:

• Management including Health, Safety and Environment (HSE) management
• Interface coordination towards other contractors
• All detailed engineering and design (based on FEED design)
• All procurement necessary to complete the two OSS
• All construction activities necessary to complete the two OSS
• Installation of Company’s Materials (e.g., HV equipment)
• Mechanical Completion (MC), functional testing and certification of equipment
• Both topsides and jackets prepared for load out, transportation and preservation.
• Intermediate storage, if relevant prior to load-out for transportation/installation
• Offshore hook up and commissioning assistance
• Contract close out activities required for issue of the Completion Certificate

Main description of OSS:

The OSS is categorized as normally unmanned; however, it is equipped with an emergency shelter including welfare facilities and overnight stay for 12 persons in the permanent operative phase. The OSS will be equipped with a helicopter winch area for emergency transfer of personnel. The primary means of access will, however, be by Service Operation Vessel (SOV) and/or Crew Transfer Vessel (CTV). The OSS will be designed with walk-to-work access facilities.

The deck levels are:

Jacket

• Cable deck
• Jacket structure supports 10 J-tubes for IAC and 2 J tubes for EXC
• Caissons for sea ice protection for IACs

Topside

• Cellar deck
• Main deck
• Cooler deck
• Utility deck
• Roof deck

The basic scenario involves the transportation and installation of wind turbines' foundations and foundations with offshore substation platforms (OSS) under a single contract, including the following structures within the package:

• OSS jacket
• OSS topside
• OSS piles

The selected supplier will have the following main activities in its scope:

• transport engineering
• installation and installation aids engineering
• lifting equipment and tools
• piling hammers
• piling noise mitigation equipment
• grouting spread
• vessel grillage and seafastening
• bolting spread and installation gripper frame