The export cable has been laid
On 15 October 2010, Stemat Spirit finalised the laying of the 45-kilometre long export cable and left the installation area. The export cable connects the national grid in Heysham with the offshore substation placed within the Walney 1 Offshore Windfarm. 
 


On the route, the export cable crosses some areas with extremely hard soil. Here the cable has been surface laid in sections, and now the cable is buried using a remotely operated underwater rockcutter/chaincutter to cut a trench for the cable. 

The pictures show the chain cutter, and on the right picture you can clearly see the cutting teeth.

There is, however, still remaining works to be done before the cable can be put in operation.

Splicing of the cable cut
Two kilometres off the shore at Heysham the cable repair vessel Pontra Maris has begun the splicing of the cable cut. The cable is a three core 132kV cable complete with a 48 core fibre optic cable, and both the power cables and the fibre optic cables have to be joined. The splicing work is estimated to be completed within 10 days – as always depending on the weather.

Export cable installed on the offshore transformer substation
On Sunday 10 October 2010, with the help of the cable barge Stemat 82, a four-hour long steady and calm cable pull brought the export cable to its final destination on the offshore transformer substation. Here the cable ends are being terminated and the fibre optic cables are currently being joined.

Extensive test before the power can be switched on
Until now the only power available on the substation has been produced by diesel driven generators, and before the mainland connection can be switched on, a number of electrical tests have to be performed to secure a safe commissioning of the offshore substation before the substation can collect the power from the 51 turbines in the Walney 1 Offshore Windfarm.

First cable pull at the offshore substation
On 22 September 2010, the first turbine was connected to the offshore substation as the platform connecting the cable from turbine C05, situated 527 metres to the west of the substation, was pulled up to the substation.
 


The cable is a 33kV cable containing three fibre optic cables. The cable has an overall diameter of 139mm and weighs 34 kilos per metre.

Increased installation activity
Up till now, seven array cables and 23 wind turbines have been placed in the area, but in the coming month the installation activity will be even more intensified. The cable installation vessel Normand Mermaid and the turbine installation vessel Sea Worker will both join in shortly and double the installation activity.

The jack-up barge Sea Worker during the installation of 3.6MW turbines at Gunfleet Sands.

  View from the installed nacelle. Below you can see the walkway connecting the installation vessel Kraken with the turbine.

   Bird's-eye view of Kraken. 

Armour stones for scour protection
On five turbine positions where the cables have been installed, the cable and the so-called J-tube, in which the cable is placed, are armoured with a layer of rocks for scour protection. The vessel Pompei places the stones in a radius of 15 metres around the foundation.

Offshore substation for Walney 2 under construction
Just as the substation for Walney 1 is under commissioning, the next topside and jacket for Walney 2 is under construction at Bladt Industries in Aalborg (DK). The topside and jacket for Walney 2 is almost identical with the one used at Walney 1, the only difference being a slightly higher jacket for Walney 2 to compensate for an increased water depth. The offshore substation for Walney 2 is scheduled for installation mid-May 2011.

Status of construction in October 2010.

Walney 2 onshore cabling work and substation construction
Installation of the onshore cable at Cleveleys near Blackpool is now well underway with 27% of the ducts installed in open cut trenches on the route from the sea to the new substation. Planning for the horizontal directional drilling across the seawall and a number of other obstacles is almost complete. Piling for the foundations of the substation has taken place – the foundations also elevate the building to prevent risk of flooding. 

More details on the onshore cabling for Walney 2

 

 

 

 

The Walney Offshore Windfarms The Walney Offshore Windfarms project is located approximately 15km west of Barrow-in-Furness in Cumbria. The project consists of Walney 1 and Walney 2 each with 51 - 3.6MW turbines, giving a total capacity of the Walney project of 367.2MW. The rotor diameter of the turbines is 107m for Walney 1 and 120m for Walney 2, with a maximum height of 150m from blade tip to sea level. The total area of the development is some 73km2.