Adjustable Wind Turbine Coupling for Torsional Oscillation Control
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Solution Overview
Problem
Permanent magnet generators in wind turbines face issues with uncontrolled torsional oscillations due to short circuits, leading to resonance and extreme loads, which existing solutions like fuses or increased drive train stiffness are costly or detrimental to performance.
Innovation Solution
Incorporating an adjustable coupling with flexible elements and hydraulic chambers in the drive train, allowing for dynamic adjustment of torsional stiffness to avoid resonance, either by decreasing or increasing stiffness based on the situation to keep the natural frequency above or below the excitation frequency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If the drive train stiffness is increased to avoid resonance, then the torsional natural frequency increases, but the cost and complexity of the system increases significantly
Solution Approach 1:
The coupling device incorporates adjustable stiffness characteristics, allowing the torsional stiffness to be modified dynamically. This enables the natural frequency to be adjusted to avoid resonance with excitation frequencies without requiring a permanently stiffened drive train structure, thus resolving the contradiction between stability and device complexity.
Solution Approach 2:
The invention changes the torsional stiffness parameter of the coupling device to modify the natural frequency of the drive train. By adjusting this parameter, the system can avoid resonance conditions without permanently increasing the overall stiffness of the drive train, thereby avoiding the associated costs and complexity.
2Object-affected harmful factors
If fuses or circuit breakers are incorporated to prevent uncontrolled currents, then the harmful effects are reduced, but the device complexity and cost increase
Solution Approach 1:
The invention extracts the harmful effect of uncontrolled currents by allowing them to decay naturally through the adjustable coupling mechanism, eliminating the need for additional electrical protection devices like fuses or circuit breakers. This reduces device complexity while still protecting against harmful effects.
3Force
If the rotor is braked to reduce speed, then the torsional load decreases, but the stopping time increases significantly due to large inertias
Solution Approach 1:
The adjustable coupling provides dynamic damping that actively reduces torsional oscillations during the braking process. This allows the rotor to be stopped more quickly without subjecting the drive train to excessive torsional loads, resolving the contradiction between force reduction and time loss.
4Stability of the object's composition
If the coupling stiffness is made adjustable, then the natural frequency can be optimized, but the device complexity increases
Solution Approach 1:
The coupling device incorporates adjustable stiffness characteristics, allowing the torsional stiffness to be modified dynamically. This enables the natural frequency to be adjusted to avoid resonance with excitation frequencies without requiring a permanently stiffened drive train structure, thus resolving the contradiction between stability and device complexity.
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
This approach effectively reduces the amplitude and frequency of torsional loads, preventing resonance and associated destructive loads, offering a simpler and cost-effective solution compared to traditional methods.
Implementation Method 1
The adjustable coupling may comprise flexible elements and one or more hydraulic chambers in the flexible elements to adjust the stiffness of the flexible elements
Implementation Method 2
As the permanent magnet rotor rotates, its magnetic field will cause an electromotive force and thereby currents in the stator
Implementation Method 3
one or more overpressure valves to release hydraulic fluid from the hydraulic chambers
Data Source
Figure 1a
Figure 1b
Figure 2a
AI summary
Methods for reducing torsional oscillations in a drive train of a wind turbine, the drive train of the wind turbine including a rotor with one or more blades, a permanent magnet generator, and an adjustable coupling are disclosed. The methods comprise changing the torsional stiffness of the adjustable coupling so as to change the torsional natural frequency of the drive train. The disclosure further relates to wind turbines comprising a drive train including a rotor with one or more blades, a permanent magnet generator, and an adjustable coupling, wherein the adjustable coupling comprises one or more flexible elements and one or more hydraulic chambers in the flexible elements, and one or more overpressure valves to release hydraulic fluid from the hydraulic chambers.