What types of cables are needed to build a wind farm?

Overview: What types of cables are used in the wind farm?

When building a The following cable types are generally used for wind farms:

1. Medium voltage cable (MV cable)
   
2. Low-voltage cable (LV cable)
   
3. Fiber Optic Cable / Communication Cable
   
4. Control and data cables
   
5. Lightning protection cables
   
6. Grounding and equipotential bonding cables
   
7. Special cables (e.g. for offshore wind farms or in mobile segments of the plant)
   

These cables take over different tasks – from energy transmission to communication to protection against overvoltage and earth faults.

1. Medium voltage cable (MV cable)

Function

Medium Voltage Cable connect the individual wind turbines with each other as well as with the substation. They transport the generated electrical energy with voltages typically between 10 kV and 36 kV.

Typical designs

• Copper or aluminum conductors
  
• XLPE insulation (cross-linked polyethylene)
  
• shielding (e.g. Cu braid or conductive plastic)
  
• mechanical protective coatings for Underground laying (e.g. steel strip)
  

Challenges

• High current-carrying capacity with a long service life at the same time
  
• Thermal stress due to current flow and environmental influences (temperature, soil)
  
• Mechanical stress during underground laying or offshore use
  
• Shielding against electromagnetic Disturbances
  
• Protection against moisture and corrosion – especially in offshore wind farms
  

Special requirements

• Standards such as DIN EN 60228, VDE 0276 or IEC 60502-2
  
• Pressure tightness and longitudinal watertightness (LWD) for offshore or humid locations
  

2. Low voltage cable (LV cable)

Function

Inside the gondola and the tower, LV cables are used to power individual components – such as hydraulic systems, lighting, heating or sensors.

Typical designs

• Copper conductor, flexible design
  
• PVC or rubber insulation
  
• Halogen-free, flame-retardant materials
  

Challenges

• Vibration and bending stress on moving plant components
  
• temperature resistance, especially for offshore installations or in heated enclosures
  
• Fire protection requirements in confined spaces
  

Special requirements

• Halogen-free, low Smoke generation (e.g. HFFR cables)
  
• UV and ozone resistance in Outdoor
  

3. Fiber optic cable/communication cable

Function

Fiber optic cables are essential for data transmission within a wind farm: enable communication between wind turbines, substations, SCADA systems and Master display.

Typical designs

• Single-mode or multi-mode fibers
  
• With strain relief and outer sheath (PE or PUR)
  
• With or without metallic reinforcement
  

Challenges

• Mechanical protection during burial (stones, Ground movements)
  
• Moisture protection, especially in offshore environments
  
• Fiber optic cable break due to Bending load
  

Special requirements

• EMC insensitivity
  
• Standards such as IEC 60794-1, EN Reference 50173 
  

4. Control cable and data cable

Function

Transfer control cable Control pulses on components such as pitch system, generator control, transformers or operational monitoring systems. Connect data cable Sensors, actuators and internal control units.

Typical designs

• Multi-core copper cables
  
• Shielding against electromagnetic Disturbances
  
• Flexible insulation for moving Uses
  

Challenges

• EMC interference due to nearby power cables
  
• Bending and torsional load due to movable nacelle
  
• Temperature differences indoors and outdoors
  

Special requirements

• CE, UL, or CSA approval depending on the Exporting country
  
• Flame retardancy, halogen-free
  

5. Lightning protection cables

Function

Conduct lightning currents controlled from the rotor blade tip to the nacelle and the tower to the soil. Indispensable for the protection of electrical components and for personal protection.

Typical designs

• Galvanized steel or copper conductors
  
• Copper strips capable of carrying lightning current, or -ropes
  
• Connection to Grounded Arresters
  

Challenges

• High current load with a short duration (up to 200,000 A)
  
• Mechanical and thermal resistance
  
• Corrosion protection in salty air
  

Special requirements

• DIN EN 62305-3
  
• Protection concept in combination with Earthing system
  

6. Grounding cables and equipotential bonding cables

Function

Ensure that no dangerous potential differences occur in the wind farm. You protect Humans and technology alike face voltage differences and guide residual currents.

Typical designs

• Copper ropes with high cross-sectional thickness
  
• Grounding tapes in the nacelle and in the Foundation
  
• Connection of all metallic Housing parts
  

Challenges

• Durability in the soil (corrosion resistance)
  
• Possibility of laying ground and contact with the Soil
  
• Secure connection with foundation earthing or Ringerder
  

Special requirements

• DIN VDE 0100-540, 0185-305
  
• Lightning current carrying capacity
  

7. Special cables for offshore wind farms

Function

Offshore wind farms additional requirements: long distances, damp and salty climate, extreme temperatures and constant movement by waves.

Typical designs

• Subsea cable (submarine cable)
  
• Polyethylene (PE) sheath or Specially sheathed steel armor
  
• Extra long life cycle (>30 years)
  

Special challenges

• Pressure and salt water resistance
  
• Weather resistance (heat, wind and frost)
  
• Long shelf life
  
• Flexibility
  
• Longitudinal watertightness
  
• Difficult handling when inserting under Water
  
• High costs due to special production and installation
  
• Fast delivery, availability and processing

Special requirements

• Standards such as IEC 62067, IEC 60228
  
• Acceptance by international Testing institutes
  

Planning and project planning: What do operators of wind farms have to consider?

When selecting and Planning the cable infrastructure of a wind farm should include the following aspects: The following are taken into account:

1. Location analysis

• Topography, subsoil, moisture
  
• environmental factors (UV radiation, Salinity, temperature fluctuations)
  

2. Grid connection requirements

• voltage level and Transformer connection
  
• Protection and communication requirements
  

3. EMC planning

• Separation of power and control cables
  
• Shielding and installation to EMC criteria
  

4. Economic feasibility study

• Choice of durable cables reduced Maintenance and replacement costs
  
• Investment in high-quality materials pays off in the long run
  

5. Documentation and compliance with standards

• Seamless cable lists and routing plans
  
• Certificates for fire behaviour, Environmental resistance, CE conformity
  

The cabling of Wind turbines is more than just laying cables – it is a critical component for trouble-free, safe and efficient Operation of a wind farm. The selection of suitable cable types, tailored to location, system concept and requirements, determines the quality and Durability of the entire infrastructure.

wind farm operators and Project developers should therefore build up specialist knowledge at an early stage, with experienced planners and manufacturers and in the selection of components rely on certified quality.