HVDC > HVDC Light > Applications > Wind farms
HVDC Light makes it easier to develop environmentally friendly generation sources.
Onshore wind farms
One example of an onshore wind farm transmission is Gotland HVDC Light. The two main reasons for choosing the HVDC Light solution for this 50 MW, 70 km transmission were:
- Great difficulties were experienced in getting the necessary permits to build an additional overhead transmission line. With HVDC Light underground cables, the necessary permissions were easy to obtain.
- HVDC Light could maintain a good power quality (reduction of flicker) for the consumers despite the variable operating conditions for wind power plants that cause variations in reactive power.
These reasons apply also for offshore wind farm transmissions.
Offshore wind farms
In many countries the best onshore locations for wind farms are already developed, and the utilities are turning to offshore sites. The main attraction of going offshore is the enormous wind resource available. Average wind speeds can be 20 percent higher, and the resulting energy yield up to 70 percent greater than on land. The lack of obstacles such as hills, and the generally smooth surface of the sea, also makes the wind more reliable.
With more and larger wind parks set to be built offshore, major investments are needed to find ways to feed the power into the grid. The alternating current technology used in the first, smaller offshore wind parks is increasingly reaching its limits on account of the high reactive power demand of the cables. For wind farms distant to the coast, HVDC Light is the ideal means to bring the power to shore and to assure a good power quality.
The HVDC Light converter stations have a small station footprint and low weight - a fact that is of particular importance in the offshore station.
The on-shore (receiving) converter station can be located close to the shore or further inland. The grid is sometimes rather weak (radial structure) along the coastline, but this may not neccesarily be a problem, since HVDC Light can be connected to weak points. But it is also easy to bring the connection point to a major substation at some distance from the shore by means of the HVDC Light cables.
The first example of a HVDC Light wind farm transmission offshore is the 400 MW
NORD E.ON 1. This transmission brings power from windfarm 130 km from the German North Sea coast to a substation 75 km inland by submarine and underground cables.