Inter-Array cables

Designing the layout of interconnection cables for offshore wind farms is a key element in ensuring efficient and safe power transmission. The process takes into account the network topology and cable parameters, which are optimized based on information about the turbine, performance, wind parameters and export cable configuration. The goal of the design is to minimize transmission losses, investment and operating costs over the life of the farm. The design of the internal cable system also takes into account wind turbine generator specifications, cable laying requirements and reliability parameters. The impact of offshore substation locations on the internal cable network is also evaluated.

The number of turbines included in one group of internal cables depends on their power output and is determined at the detailed design stage. The layout plan for the internal cables depends on the final location of each wind turbine, as well as the number of groups. It is possible to use one of two technologies, i.e. copper-core cable or aluminum-core cable. The decision on the choice of technology is made after a series of technical analyses and a detailed design.

The effective operation of an offshore wind farm depends to a large extent on the quality of the interconnection of multiple wind turbines by means of internal cables, known as "array cables." These cables form loops or single strings, connecting all the turbines to an offshore transformer substation. There is up to 1.5 kilometers of cable for each turbine, depending on the size and distribution of the turbines. With the deployment of larger turbines above 10 MW, the size of the cables increases, as well as the voltage. Internal cables are usually supplied with accessories. It is possible to use one of two technologies, i.e. copper-core cable or aluminum-core cable. The decision on the choice of technology is made after a series of technical analyses and a detailed design.

The Supply and installation of 66 kV AC inter-array cables incl. accessories & equipment with a total transmission capacity of 1440 MW (2x720MW). The Inter Array Cable Systems connect the WTG foundations into ~20 strings to the  offshore substations (approx. 180 km total IAC length). Each string will contain 5-6 WTGs. The inter-array cable systems shall include fibre optic cable and be equipped with cable monitoring system.

The inter-array cable EPCI Scope of Work includes the following main activities: 

• Preliminaries  
• Engineering and documentation   
• Interface coordination   
• Procurement, fabrication, and testing   
• Load-out, transportation   
• Storage and preservation  
• Construction, installation and cable protection incl. cable pull-in, termination and jointing at OSS and each WTG  
• Mechanical Completion   
• Final documentation 
• Contract close out activities required for issue of the Completion Certificate