How can you properly ground wind turbines in grid-connected systems?

1 Grounding concepts

Grounding is the process of connecting electrical equipment or conductors to the earth or a reference point, such as a neutral wire, to provide a path for fault currents, stabilize voltage levels, and reduce electromagnetic interference. Grounding can be classified into two categories: system grounding and equipment grounding. System grounding refers to the connection of the power source or the generator to the ground, while equipment grounding refers to the connection of the metallic parts of the equipment, such as the tower, the nacelle, and the blades, to the ground. Both types of grounding are important for wind turbines, as they protect the system from overvoltages, short circuits, lightning strikes, and fire hazards.

2 Grounding schemes

Different grounding schemes can be used for wind turbines depending on the type of generator and grid connection. The most common schemes are solid grounding, resistance grounding, reactance grounding, and ungrounded. Solid grounding is the simplest and most widely used scheme, connecting the generator or transformer directly to the ground with low resistance. This provides good fault detection and clearance but can also cause high fault currents and equipment damage. Resistance grounding connects the generator or transformer to the ground through a resistor that limits the fault current to a safe level, reducing arc flash risk but creating transient overvoltages and harmonics. Reactance grounding connects the generator or transformer to the ground through a reactor that creates a high impedance to the fault current, minimizing fault current and transient overvoltages but causing voltage instability and resonance. Ungrounded eliminates fault current and transient overvoltages but can lead to insulation failure and undetected faults.