The Horns Rev project is now taking shape. The first parts for the project are being manufactured and shortly, almost all parts for the project will be in production to be in available and in place on time for the start of installation on March 4, 2002. The main activities and milestones are shown on the schedule.

The windfarm at Horns Rev presents new kinds of problems, which have not been experience earlier in connection with windfarms - caused especially by the difficult access conditions and the latest demands for load control set up by Eltra as well as Elsam's operation department.

The monitoring technologies used are the same as the ones used for onshore plants in which reliability-centred maintenance is practised. The control systems of the turbines regularly collect operating statistics for all essential components such as gear, generator, yaw system, pumps, etc. Furthermore, all the turbines are fitted with a state-of-the-art vibration control system, which monitors main bearings, gear and generator and reports/sets off an alarm when a measuring point shows sign of change in the condition of a monitored component. All data are regularly transmitted to the remote control and monitoring system from where Elsam's central maintenance system has access to the data.

The need for load control requires the same kind of control of the windfarm's production as a combined heat and power plant unit. An example could be reducing the production from the windfarm due to grid limitations and/or participating in a load control scheme within the limits of actual wind speeds.

This requires a broad band communication system of a reasonable price, reliability and flexibility to meet future and yet undefined demands as well as immunity to electrical interruptions including for instance lightening.

These various requirements have resulted in a solution based on fibre optics and Internet technology based on TCP/IP protocol. The turbines are placed in ten circles of eight turbines each, which are connected in a 100 Mb Ethernet of fibre optics in the high-voltage cables which again connect the turbines to the substation.

The signals from the substation will be transmitted via the fibre optic cables in the 150 kV submarine cable or, alternatively, via an radio signal chain to Esbjergværket where all data are collected and where the day-to-day control and monitoring of the windfarm will take place.

On October 22, 2001 the Rambiz returned to Esbjerg Harbour from Horns Rev in search for shelter after a week of changing weather and wave conditions. It had not succeeded in driving the three large M-piles for the substation. In stead, time had been spent on mounting the boat landing arrangement (welded construction, work not finished yet.) and on driving the large pile for the J-tube for the submarine cable to the shore.

As described earlier in our October newsletter, the movements of the ship caused by waves are amplified in the 85-m high crane boom. This means that the driving of piles, which is a job requiring immense precision, was not possible and with a weather forecast not promising improvements in the weather, the Rambiz had to return to Esbjerg.

The boat landing arrangement has later been reinforced to withstand winter storms by the help of the boat Naomi B.

The tripod construction for the turbine cables have been installed and the three piles have been driven including test pile A1, which was to be monitored during the driving session. The tripod construction has not been grouted yet but preliminary calculations made by Dutch HBG do not cause any concern about damage occurring during a possible storm. The grouting will commence as soon as possible to have sufficient settling temperatures.

It turned out that the Rambiz had to stay in Esbjerg Harbour longer than expected and worries emerged as to whether the outstanding tasks could be finished before winter set in. It is therefore of utmost importance that the necessary measures are taken as soon as possible to minimise the risks. On November 15, 2001 HBG decided to remove equipment from the barge and transfer the barge to a fortnight's job in Belgium.

Since the placement of the three piles is crucial to the design and construction of the support bearings of the substation, it is of utmost importance that phase 1 is completed as soon as possible. The constructor is currently evaluating the various possibilities of driving the three piles with sufficient precision and independently of wave impact. A decision is expected very soon.

Vestas has completed the manufacturing of the tower and blades for the prototype turbine scheduled for erection in Tjæreborg on December 5, 2001. The finishing of the nacelle is currently made at Vestas' production facilities in Ringkøbing, Denmark.

The design of the new turbine to be erected in Tjæreborg is almost an exact copy of the design of the eighty turbines to be erected at Horns Rev in 2002. A heli-platform will be fitted on top of the turbine's nacelle for hoisting fitters on to the turbine from a helicopter, for testing the installation of the turbine marking on the nacelle's roof and for various advanced controls. The erection of the prototype thus provides numerous opportunities for testing the turbine thoroughly before the erection at Horns Rev.

Prototype data:

Once again nature has shown us its great forces offshore in the North Sea. This time, a small songbird called the thrush is the victim of nature's great forces.

In connection with the pile driving for the substation a strange phenomenon was discovered in last September. The Rambiz and other vessels were suddenly invaded by "tame" songbirds, which flocked around the vessels and landed on decks, inside the wheelhouse, on the shoulders and heads of the workers, anywhere possible. But a closer look revealed that the birds were not tame. They were exhausted and were looking for a place to rest. Some of the birds were so exhausted that they literally dropped dead on the decks while others continued after a short rest. The workers had to brush the birds off the decks in able to work.

What had happened?

During autumn, thousands of songbirds migrate along the west coast of Jutland. Sometimes the easterly winds are so strong that the birds are forced away from their normal migration route. This happened at exactly the same time as the construction work at Horns Rev and some birds were forced to cross over the Horns Rev where the vessels became their only steady ground.

The weather plays an important role in connection with implementing the planned activities at Horns Rev. You can follow the weather conditions in the North Sea by visiting the homepage of DMI giving forecasts of:

In connection with the construction of the Horns Rev windfarm Elsam will install various auxiliary equipment on the substation such as: 34 kV switchgear, house load transformer, shunt reactor and a 1,000 kW diesel generator. These components will be installed at Eltra's Horns Rev substation and should therefore be ready for supply by December 22, 2001.

The diesel generator is needed for Horns Rev in order to establish an auxiliary supply of electricity to the substation as well as to the turbines. It is also required for maintaining navigation and marking of turbines and for keeping the various systems warm and dry in case the connection to the shore is cut off for a long period of time. The capacity of the diesel generator corresponds to the consumption of approx. 2,000 standard households.

The distributor and the diesel generator are installed in containers, which are designed according to offshore standards. This means they are able to withstand the loads which they are subjected to during offshore transportation. In case of considerable damage, the entire container may be taken off the substation and taken ashore for repair. Preparations have been made for this and in that connection lifting of the containers has been tested. The tests included loading the containers with 2.5 times standard load. Since the containers were not large enough physically to hold 50 tonnes (e.g. the distributor) four leads of 7.5 tonnes each were attached to the containers during the lifting tests.