Case studies(Introduction examples)

Lightning protection for wind power generation systems

Unobstructed wind power systems should be exposed to direct lightning strikes.

Due to the nature of the equipment, wind power generation systems installed on vast unobstructed sites are designed on the assumption that they will be subjected to direct lightning strikes, but lightning damage will occur if a larger-than-expected lightning strike occurs.
When damage occurs, the shunt component of the direct lightning strike may enter the wind turbine and cause severe damage to the equipment. In addition to damage to the equipment, the wind turbine itself can also be severely damaged. In the past, wind turbines have been struck by lightning, causing the blades to detach.

In the case of wind turbines installed on mountaintops, some of them are built on bedrock with hard soil. In such cases, the ground resistance is higher, and it can be said that a potential difference is more likely to occur (making them more susceptible to lightning surges).

Dangers if no measures are taken
  • Blade separation and breakage due to direct lightning strike
  • Damage or malfunction of wind turbine equipment
  • Suspension of wind power generation equipment operation until equipment is restored

Lightning protection points for wind power generation systems

Countermeasure points
In general, wind turbines generate power at 600V to 690V, but in order to connect them to the power grid, inverters and converters are used to convert the voltage from AC to DC to AC and adjust the frequency. Then, a transformer is used to boost the voltage to 22kV, and the system is connected to a substation.

Then, a 600V AC SPD is installed to protect the power supply system from lightning surges. For the control unit, a signal line SPD (model: SA-GZA series) with a large withstand capacity is installed. It is also appropriate to use a lightning resistant transformer to insulate the system.

Since direct lightning strikes are expected on the windmill itself, the potential of the windmill itself rises, and the shunt component of the direct lightning strike may flow into the equipment inside the windmill, so SPD for interconnection between grounds is installed to handle the lightning surge flowing in from the ground.

Since lightning surges may also penetrate transformers, a 22kV extra-high polymer lightning arrester will be installed. An indoor surge arrester is installed in the substation, and an outdoor surge arrester is installed in the distribution line. Since the outer coating is made of polymer material, it can be smaller and lighter than the conventional porcelain type.

If the grounding resistance is high, lightning damage may increase, so grounding resistance reduction material is used to improve grounding.

Installation example

Lightning protection products for wind power generation systems