Wind Turbine Rotor Blade Load Envelopes for Extreme Load Control
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Solution Overview
Problem
Wind turbines face challenges in effectively managing extreme loads on rotor blades due to fluctuating environmental conditions, which can lead to component damage and failure, and existing load control systems are complex, expensive, and prone to inaccuracies.
Innovation Solution
A method and system utilizing an envelope-based blade root bending moment control algorithm that calculates and filters blade root bending moments, predicts future loads, and implements control actions such as pitching the rotor blades to mitigate extreme loads.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If sensors are used to measure loads acting on wind turbine components, then load measurement accuracy is improved, but system complexity and cost increase
Solution Approach 1:
The patent replaces physical sensor systems with a computational model that calculates blade root bending moments using aerodynamic parameters (thrust, pitch angle, rotor speed, air density) and structural parameters. This substitution eliminates the need for complex sensor installations while providing accurate load estimates through mathematical modeling.
Solution Approach 2:
The patent creates a virtual copy of the physical blade structure through computational modeling. Instead of measuring the actual blade loads with sensors, the system replicates the blade's structural behavior through finite element analysis and aerodynamic calculations, providing equivalent information without physical contact.
2Measurement precision
If sensors are installed to measure loads on wind turbine components, then load information accuracy is improved, but installation cost and reliability issues increase
Solution Approach 1:
The patent eliminates sensor reliability issues by replacing physical measurement devices with a computational approach. The system calculates blade root bending moments using reliable input parameters (thrust, pitch angle, rotor speed, air density) that can be measured by simple sensors or derived from operational data, avoiding the complexity and failure modes of dedicated load sensors.
Solution Approach 2:
The computational model serves itself by using the wind turbine's own operational parameters (thrust, pitch angle, rotor speed) to calculate its own blade loads. This self-service approach eliminates the need for separate sensing systems and their associated reliability concerns.
3Object-affected harmful factors
If existing load control systems are used, then extreme load management is attempted, but system complexity and cost increase
Solution Approach 1:
The patent implements preliminary action by calculating the blade root bending moment envelope in advance and comparing it against predefined threshold values before extreme loads occur. The control system proactively identifies potential overload conditions and triggers protective actions (pitch control, shutdown) before damage can occur, rather than reacting after sensors detect excessive loads.
Solution Approach 2:
The patent replaces complex mechanical sensor-based control systems with a computational approach that uses aerodynamic and structural models to predict blade loads. The control decisions are based on calculated bending moment envelopes compared against design limits, eliminating the need for complex real-time sensing and control hardware.
4Device complexity
If thrust-based control algorithms are used to estimate loads, then control simplicity is improved, but load estimation accuracy deteriorates
Solution Approach 1:
The patent enhances the simplicity of thrust-based algorithms by systematically varying and incorporating multiple critical parameters: thrust, pitch angle, rotor speed, air density, blade mass distribution, and structural stiffness characteristics. By changing these parameters in a structured way within the computational model, the system achieves both simplicity and accuracy in load estimation.
Solution Approach 2:
The patent applies local quality by considering the specific structural characteristics of the blade root section where bending moments are calculated. The model accounts for local structural properties (moment of inertia, section modulus) and aerodynamic characteristics at different locations along the blade, providing accurate load estimates without requiring complex system-wide measurements.
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
Effectively reduces extreme loads on wind turbine rotor blades by providing accurate load control, enhancing component durability and reducing the risk of failure.
Implementation Method 1
The rotor blades are the primary elements for converting wind energy into electrical energy. The blades typically have the cross-sectional profile of an airfoil such that, during operation, air flows over the blade producing a pressure difference between its sides. Consequently, a lift force, which is directed from the pressure side towards the suction side, acts on the blade.
Implementation Method 2
The thrust force comes from a change in pressure as the wind passes the wind turbine and slows down.
Data Source
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AI summary
A method for reducing extreme loads acting on at least one rotor blade of a wind turbine includes calculating, via a processor, a flapwise bending moment of the rotor blade(s). Further, the method includes calculating, via the processor, an edgewise bending moment of the rotor blade(s). The method also includes calculating, via the processor, an average load envelope of a blade root bending moment of the rotor blade(s) as a function of the flapwise bending moment and the edgewise bending moment of the rotor blade(s). Moreover, the method includes calculating, via the processor, an overall load envelope of the blade root bending moment of the rotor blade(s) as a function of the average load envelope and a future load estimation of the blade root bending moment of the rotor blade(s). As such, the method also includes implementing, via the processor, a control action when the overall load envelope is above a certain threshold.