Resistivity measurements on Wind Turbine Lightning Protection Systems (LPS)

Highlights

  • Complete inspection of the LPS system by measuring each receptor
  • There was no need to rotate the blades. The inspection was carried out in a Y configuration. over 200m of flight is feasible.
  • Cut inspection time by 80%
  • Cut inspection costs by 50%
  • Compliant to standard EN 62305-3.

 

Problem Description

Wind is a renewable energy source that is clean, free, and widely available. Every day, an estimated 260000 wind turbines capture wind energy and convert it to electricity worldwide.

Despite the fact that wind turbines are outfitted with LPS, lightning strikes continue to destroy blades and entire turbines. Given that wind turbines have a design life of up to 25 years, it is critical to protect them against lightning strikes, since the damage caused by lightning strikes may result in downtime of the turbine operation, additional maintenance expenses, and a lack of power. According to recent research, lightning strikes caused 85% of downtime and were the source of 80% of insurance claims. As a result, a well-working LPS system is critical.

The traditional rope access technique is time-consuming and carries all the risks of working at height.

Solution Description

The payload was a Portable Micro-Ohmmeter. As these Ohmmeters are typically >5kg, it is too large to be carried with the UAV and remains on the ground, from here it is grounded to the wind turbine and the Voliro T takes the measurement sensor (a 4-point probe) and cable from the Ohmmeter up to the blade. When the sensor carried by the Voliro T is in contact with the LPS receptor, the loop is completed and the bulk resistivity measurement can be recorded and this measurement still meets the requirement of the standards

From trials on an onshore wind turbine farm, the full LPS measurements on a 3.5MW turbine were completed in just 40 minutes, saving almost a day over traditional rope access methods. Due to the 250m tether length, it is needed not needed to turn the rotor to inspect blades at the 6 o’clock position.