We are primarily tasked with providing power transmission services, system services and facilitating the energy market. Our core tasks follow from our appointment as grid operator under the Dutch 'Elektriciteitswet' (E-wet) and the German 'Energiewirtschaftsgesetz' (EnWG).
Maximum performance at sea and on land
In order for the wind power generated at sea to be fed into the transmission grid, the offshore wind farms must be connected to the mainland. This involves a great deal of technical effort and extensive work. For the electricity produced in the North Sea to be transported to consumers, maximum technical performance at sea and on land is required. The individual offshore projects in the North Sea are connected to the power grid using either three-phase or direct current technology. Smaller wind farms near the coast in particular are usually connected directly to the mainland via three-phase power cables.
However, the majority of offshore wind farms are located in the middle of the North Sea and far from the mainland. The distance to the coast is often more than 100 kilometres. TenneT uses direct current cables to ensure that the wind power produced in large quantities can be transported over this distance with as little loss as possible and fed into the extra-high voltage grid on land. With only one positive and one negative pole each, this technology is gentle on nature and allows a narrow route to be built on land.
This is how the energy reaches land from the sea
On its journey from the North Sea to the mainland, the elektricity passes through several stations. The three-phase current generated in the offshore wind farms is first collected in the transformer station of the wind farm operator. From there, it is forwarded to the converter platform at sea via a three-phase current cable. There, the wind power is converted from three-phase to direct current so that it can be transported ashore with as little loss as possible. At the same time, the current in the system is smoothed. This makes it easier to control the entire system. The electricity is then transported via a DC cable on the seabed and overland to the onshore converter station. Once ashore at the converter station, the direct current is converted back into three-phase current. From there, it is fed into the extra-high voltage grid via a transformer station and is available to households and industrial companies after distribution by the regional grid operators.
The heart of our offshore grid connections, because only through them can the energy be transported from sea to land and from there to the consumer.Read more
In order to bring the energy generated in the North Sea to land as efficiently as possible, we use high-performance transmission cables at sea and on land.Read more