Offshore Wind Power: Connection Technology for Harsh Conditions

Germany continues to expand its offshore wind power capacity. With the recent updates to the German Offshore Wind Energy Act, the government aims to improve reliability and provide long-term stability for expansion efforts. For the industries involved, this means sustained demand for high-performance, reliable components for everything from wind turbines to grid connections.

Cables and wires also play an important role in this expansion. Offshore environments expose electrical components to particularly harsh conditions. At the same time, wind turbines are becoming more efficient, and demands for system availability continue to increase. As a result, reliable electrical infrastructure capable of withstanding these conditions is essential. However, not all cables are designed for the same applications. Requirements can vary significantly depending on where the cables are installed within the wind turbine.

Cables within the “cable loop” face particularly demanding conditions. As the nacelle rotates to follow the wind, the low- and medium-voltage cables installed there are continuously subjected to torsional forces, causing them to twist along their own axes. Conventional cables are not designed to withstand these mechanical stresses over extended periods.

HELU developed the HELUWIND WK Torsion series specifically for this application, including the WK 110, WK 135, and WK 137. These low-voltage cables are designed to withstand torsional loads of ±150 degrees per meter. The HELUWIND WK series has been tested for more than 18,000 torsion cycles.

In addition to its mechanical durability, the HELUWIND WK series offers several other important features. These cables are resistant to UV radiation, ozone, abrasion, and oils, are halogen-free, and are designed to operate reliably in salt-laden environments. Their operating temperature range extends from -40 to +90°C in both continuous-flex and fixed installations. Depending on the cable type, the HELUWIND WK series also 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 supports their use in international markets.

In modern wind power systems, communication systems are becoming increasingly complex and important. Sensors continuously monitor operating conditions, control systems process information, and various components exchange data with one another.

This means that fiber-optic cables, as well as data, bus, and control cables, have become essential components for ensuring system availability. Depending on the application, these cables must be resistant to electromagnetic interference, oil, and UV radiation, or designed to withstand movement and a wide range of temperatures.

Engineers must therefore consider more than just transmission speed. The cable must also meet the mechanical and electrical requirements of its intended application.

Machine malfunctions on the shop floor can be frustrating, but offshore, they can quickly lead to costly disruptions. Maintenance and repairs at sea are challenging and often depend on weather and sea conditions.

That is why it is especially important to ensure that the connection technology is suitable for the application before construction begins. Cable selection involves more than just conductor cross sections and voltage ratings. Factors such as torsion, bending radius, operating temperature range, resistance to UV radiation, ozone, and oil, fire performance, and applicable standards must also be considered.

To ensure its cables and wires meet the demands of these applications, HELU utilizes its own state-of-the-art testing center, which includes a replica wind turbine specifically designed to test cables for torsional performance. The testing center also features equipment for fire, abrasion, and bending tests.

A wind power system places a variety of demands on its cables. A cable subjected to continuous movement in a cable loop must withstand different mechanical stresses than power, data, sensor, or communication cables in fixed installations. This is why electrical connection technology should be considered early in the system planning process, rather than selecting cables based solely on their electrical specifications.