Veja Mate completes array cable installation

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Veja Mate Offshore Wind Farm is most pleased to announce the completion of its array cable installation and post-lay burial activities 10 weeks ahead of schedule.

Cable installation started on October 1st 2016 and since then Siem Offshore Contractors (SOC) successfully installed 73 composite submarine power cables totaling 97 km in length using their Siem Aimery and Siem Moxie vessels for cable laying and installation support. Termination and testing activities will be completed within the next few weeks.

Veja Mate´s Inter-Array Cable (IAC) Package and SOC´s Project Management, crews and vessels have proven their capabilities of executing cable installation works to the highest safety- and quality standards within a challenging offshore environment during a winter campaign. Veja Mate’s IAC Package Manager Klaus Zwirlein, said “We are happy to have brought this project to a successful end, ahead of schedule. Although the weather was kind to us, our achievement was realized thanks to the great team effort of our IAC staff and SOC project teams for their dedication and commitment.“

Veja Mate is a 402 MW, 1,9 bn EUR offshore wind project owned by the Highland Group Holdings Ltd, Siemens Financial Services and CI II managed by Copenhagen Infrastructure Partners. Bank financing was completed on the 1st of July 2015. Construction started on the 4th of April 2016 and the project is expected to be fully operational by the end of 2017. It will produce over 1,6 TWh of green, renewable electricity annually.

Project Overview and Significance

The Veja Mate offshore wind farm is located in the German Bight of the North Sea, approximately 95 kilometers northwest of the island of Borkum. With a total capacity of 402 megawatts (MW), it is one of the largest offshore wind projects in Germany and a key contributor to the country's renewable energy targets. The project spans an area of about 51 square kilometers, with water depths ranging from 39 to 41 meters. Once fully operational, Veja Mate will generate over 1.6 terawatt-hours (TWh) of green electricity annually, enough to power approximately 450,000 German households.

The completion of the array cable installation marks a critical milestone in the project timeline. Array cables are the submarine power cables that connect individual wind turbines to the offshore substation, where the electricity is collected and transformed before being transmitted to shore via export cables. The successful and early completion of this phase underscores the project's commitment to efficiency and safety, and it paves the way for the final stages of commissioning and grid connection.

Technical Details of the Array Cable Installation

The array cable system for Veja Mate consists of 73 composite submarine power cables, totaling 97 kilometers in length. These cables are designed to withstand the harsh marine environment, including strong currents, wave action, and seabed movement. Each cable has a voltage rating of 33 kilovolts (kV) and is composed of three power cores, a fiber optic element for communication and monitoring, and multiple layers of insulation, armoring, and protective sheathing.

The installation process involved several key steps:

• Pre-lay survey and route preparation: Ensuring the seabed was clear of obstacles and that cable routes were optimized to avoid hazards.
• Cable laying: Using specialized vessels, the cables were carefully deployed from the turbine foundation to the offshore substation, with controlled tension and precise positioning.
• Post-lay burial: The cables were buried to a target depth of 1 to 3 meters below the seabed using a jet trencher or plow, protecting them from fishing gear, anchors, and other external threats.
• Termination and testing: The cable ends were connected to the turbine switchgear and substation terminations, followed by high-voltage testing and commissioning to ensure integrity.

Siem Offshore Contractors (SOC) executed the installation using two vessels: the Siem Aimery, a dedicated cable-lay vessel equipped with a turntable and tensioners, and the Siem Moxie, a construction support vessel that provided assistance with trenching, ROV operations, and crew transfers. The early completion was attributed to favorable weather windows, meticulous planning, and the seamless coordination between Veja Mate's IAC team and SOC's project management.

Safety and Quality Standards

Offshore cable installation is a high-risk operation that demands rigorous adherence to safety protocols. Throughout the campaign, Veja Mate and SOC maintained a strong safety culture, with daily toolbox talks, risk assessments, and continuous monitoring of weather and sea states. The project recorded zero lost-time incidents during the array cable installation phase, a testament to the effectiveness of the safety management systems in place.

Quality assurance was equally paramount. Each cable was subjected to factory acceptance tests before delivery, and post-installation electrical tests were conducted to verify insulation resistance, conductor continuity, and fiber optic performance. The early completion did not compromise quality; instead, it reflected the efficiency of the installation methodology and the experience of the crews involved.

Environmental Considerations and Stakeholder Engagement

Veja Mate is committed to minimizing its environmental footprint throughout the construction and operation phases. The array cable routes were selected to avoid sensitive habitats, such as reefs and archaeological sites, based on comprehensive environmental impact assessments. During installation, measures were taken to reduce underwater noise and sediment disturbance, including the use of closed-circuit trenchers and real-time monitoring of turbidity levels.

Stakeholder engagement played a crucial role in the project's success. Veja Mate worked closely with German authorities, fisheries organizations, and environmental NGOs to address concerns and ensure compliance with regulatory requirements. The early completion of the array cable installation is a positive outcome for all parties, as it reduces the duration of construction-related disruptions to the marine environment and local fishing activities.

Next Steps and Project Timeline

With the array cables installed and buried, the focus now shifts to the completion of termination and testing activities, which are expected to be finalized within the next few weeks. Following this, the wind farm will undergo a comprehensive commissioning phase, during which each turbine will be individually tested and synchronized with the grid. The offshore substation, which was installed in September 2016, is already in place and ready to receive power from the array cables.

The grid connection to the German transmission system is provided by TenneT via the BorWin2 high-voltage direct current (HVDC) link. As announced in a previous press release, TenneT successfully connected the offshore wind farm to the BorWin2 converter platform in December 2016. This connection enables the transmission of electricity from the offshore substation to the onshore grid, marking a significant step toward full commercial operation.

Veja Mate remains on track to be fully operational by the end of 2017, as planned. The project's progress to date is a testament to the dedication and expertise of all involved parties, from the project owners—Highland Group Holdings Ltd, Siemens Financial Services, and CI II managed by Copenhagen Infrastructure Partners—to the contractors, suppliers, and local communities. For more updates, please visit our Media page or browse other Press Releases.