Offshore Wind Power: Connection Technology for Harsh Conditions

In Germany, the plan is to continue with the expansion of offshore wind power. With the recently updated German Offshore Wind Energy Act, the German government’s goals are improved reliability and the long-term stabilisation of expansion activities. For affected industries, this means that high-performance and reliable components ranging from wind-power systems to grid connections will remain in demand long into the future.

Even cables and wires play an important role in this. On the high seas, conditions that demand the very best from electrical components are commonplace. At the same time, these systems are becoming ever more efficient and demands for availability are increasing. This is why electrical infrastructure that can operate reliably in such harsh conditions is in high demand. But not every cable is made the same. Depending on where they are used in the wind turbine, the requirements can vary significantly.

Cables within what is called the “cable loop” are in for a particularly difficult challenge. Because the nacelle turns with the wind, the low and medium-voltage cables installed there are constantly being subjected to torsion forces, meaning they are being twisted along their own axes. Conventional cables are not designed for long-term exposure to these kinds of mechanical loads.

HELU has developed the HELUWIND WK Torsion series for this exact application. This includes the WK 110, WK 135, and the WK 137. These low-voltage cables are designed to withstand torsion ratings of ±150 degrees per metre. The HELUWIND WK series has been tested with more than 18,000 torsion cycles.

In addition to its mechanical resilience, the HELUWIND WK series also scores major points with its other features. These cables are UV and ozone resistant, halogen-free, particularly resistant to abrasion and oils, and designed to function reliably in salt-laden environments. Its operating temperature range spans from -40 to +90°C in both flexing and fixed installations. Furthermore, depending on the cable type, the HELUWIND WK series meets the requirements of IEC 60332-1-2/3 for flame retardancy, IEC 60754-1 for halogen-free performance, and IEC 61034-2 for smoke density. UL/CSA certification for the WK 135 and WK 137 allows for worldwide use.

In modern wind power systems, communication systems are consistently gaining in complexity and importance. Sensors are constantly measuring operating conditions, control systems are processing information, and various components are exchanging information with one another.

This means that fibre-optic cables and data, bus, and control cables have become key components for ensuring system availability. Depending on the specific application, they must be resistant to electromagnetic interference, oil, and UV radiation, or be designed for movement and wide temperature ranges.

This means that engineers need to look at more than simply the transmission speed. The cable must also have the right mechanical and electrical specifications for its intended use.

It is already annoying when a machine malfunctions on the shop floor. But offshore, these malfunctions can quickly lead to expensive disruptions. Maintenance and repairs on the sea are difficult and can even depend on weather and swells.

That is why it is all the more important to ensure that the connection technology is appropriate for the application before construction begins. We are talking about more than merely conductor cross-sections and voltage. Factors such as torsion, bending radius, temperature range, UV/ozone/oil resistance, fire behaviour, and any relevant standard requirements must also be taken into account.

To ensure their cables and wires are up to the task, HELU utilises its own cutting-edge testing centre which includes a replica wind turbine designed specifically for testing wind power cables for torsion. The testing centre also features systems for fire, abrasion, and bending tests.

A wind power system represents more than just “a” requirement for cables. A flexing cable in a cable loop must endure different loads than power, data, sensor, or communication cables in fixed installations. It is for precisely this reason that it is worth including electrical connection technology in the planning process for systems early, and to not simply select cables based on their electrical parameters on paper.