Wind Turbine Generator Waveguide Shielding at the Airgap
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Solution Overview
Problem
Wind turbines are susceptible to damage from strong magnetic fields induced by lightning strikes, which can cause electromagnetic disturbances and induce high voltages at the airgap between the rotor and stator, potentially damaging critical components like generator windings and permanent magnets, leading to efficiency reductions.
Innovation Solution
A lightning protection arrangement featuring a waveguide, such as an electromagnetic feed line, is placed between the rotor and stator to shield electrical conductors from magnetic flux, reducing electromagnetic leakage and eliminating the need for overvoltage protection devices.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wind turbines are exposed to lightning strikes, then they generate electrical energy, but strong magnetic fields induce high voltages at the airgap that can damage critical components
Solution Approach 1:
A waveguide structure is introduced as an intermediary element between the rotor and stator at the airgap. This waveguide acts as a mediator that allows the magnetic field to pass through in a controlled manner, transforming the harmful broadband magnetic flux into a guided mode that reduces peak flux density and prevents damage to electrical conductors and permanent magnets.
Solution Approach 2:
The waveguide structure changes the parameters of the magnetic field by converting the broadband, high-intensity magnetic flux from lightning strikes into a guided electromagnetic mode with reduced peak flux density. This parameter transformation occurs through the waveguide's specific geometry and material properties, which filter and reshape the magnetic field characteristics.
2Reliability
If over voltage protection devices are added to protect generator windings, then component reliability improves, but device complexity and cost increase
Solution Approach 1:
The waveguide structure extracts and addresses the root cause of the problem by modifying the magnetic field path at the airgap. By taking out the harmful magnetic flux density issue at its source and transforming it through the waveguide, the need for additional over voltage protection devices is eliminated, thereby reducing device complexity while maintaining reliability.
Solution Approach 2:
The waveguide performs preliminary action by pre-conditioning the magnetic field before it reaches the electrical conductors and permanent magnets. The structure proactively transforms the harmful magnetic flux into a safe guided mode in advance, preventing potential damage before it occurs and eliminating the need for reactive protection devices.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The waveguide significantly reduces magnetic flux at the airgap, minimizing induced voltages and preventing demagnetization of permanent magnets, thus enhancing the reliability and efficiency of wind turbines without the need for additional protection devices.
Implementation Method 1
a lightning protection arrangement including at least one waveguide between the rotor and the stator and interposed between the external surface and the airgap for providing a shielding to the electrical conductors from the magnetic flux induced by lightning
Implementation Method 2
Magnetic fields created by lightning strikes may reach an intensity in the order of 90,000 A/m. Such a strong magnetic field may create electromagnetic disturbances and possibly damage electrical or electronic items of the wind turbine
Implementation Method 3
The waveguide significantly reduces magnetic flux at the airgap, minimizing induced voltages and preventing demagnetization of permanent magnets
Implementation Method 4
The latter may be at least partially demagnetized, hence reducing the overall efficiency of the wind turbine... preventing demagnetization of permanent magnets
Data Source
AI summary
Provide is a nacelle for a wind turbine includes: an external surface exposed to a magnetic flux induced by lightning, an electrical generator rotating about a rotational axis, the electrical generator including a rotor, a stator, an airgap separating the rotor and the stator, and a plurality of electrical conductors wound in the rotor or the stator adjacently to the airgap, a lightning protection arrangement including at least one waveguide between the rotor and the stator and interposed between the external surface and the airgap for providing a shielding to the electrical conductors from the magnetic flux induced by lightning.