Dong Energy and Vattenfall Vindkraft have signed an agreement on the supply of emergency power for each other's wind facilities if the export cables fail.
Dong Energy's offshore windfarm, Horns Rev 2, will, in the future, ensure emergency power supply for Vattenfall's upcoming Horns Rev 3 and vice versa.
Vattenfall project manager Niels Møller Jensen said: “If the export cable fails, it’s not only critical for the supply of electricity to customers on the mainland – a cable outage is also critical to the wind turbines. All turbines must always have power, especially to keep the blades’ positions correct in relation to the wind direction.
“Emergency power for the wind turbines normally comes from one single, large, centrally located generator on a platform at sea. At Horns Rev 3, we’ve chosen to install a small generator in each of the 49 wind turbines and, as something new in the industry, we’ve made an agreement with DONG Energy that we install an 8km-long 33kV cable between Horns Rev 2 and Horns Rev 3, thereby establishing a connection between both wind farms."
According to Jensen, it is an optimal economic and environmental way to secure the emergency power supply.
The small diesel generators in the wind turbines at Horns Rev 3 will ensure the power supply for a few days until Vattenfall finds out how long a potential power failure will last.
If it appears to last for a longer period, the supply from Horns Rev 2 will be switched on and the wind turbines on Horns Rev 3 will be supplied with emergency power until the export cable is back in operation, and vice versa.
Leif Winther of Dong Energy Asset Management said: "We see the cooperation with Vattenfall on the emergency power supply as a good guarantee for both windfarms, which keeps the wind turbines in good condition so that they can start producing again really quickly once the fault is corrected. It’s a relatively small investment in an emergency power cable if one looks at the total cost of an offshore windfarm."
Image: Dong Energy's offshore windfarm, Horns Rev 2, will, in the future, ensure emergency power supply for Vattenfall's upcoming Horns Rev 3. Photo: courtesy of Dong Energy.