Wind Turbine Wind Speed Estimation With Blade Torsion Pitch Correction
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Solution Overview
Problem
Existing methods for estimating wind speed at wind turbines are inaccurate, especially at high wind speeds and for turbines with flexible blades, as they do not account for the torsion effect on blade pitch angles, leading to incorrect control and energy conversion.
Innovation Solution
A method that calculates an adjusted pitch angle by adding a blade torsion contribution to the measured pitch angle, based on rotational speed and design parameters, to estimate wind speed more accurately, using a look-up table or model-based simulation, and iteratively refines the estimation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If wind speed is measured at a point behind the rotor, then the measurement is simple and direct, but the measured wind speed is affected by rotor impact and does not reflect the actual wind speed in front of the rotor
Solution Approach 1:
The patent introduces an intermediary estimation system that uses rotor speed and pitch angle as intermediate parameters to indirectly determine wind speed. Instead of directly measuring wind speed behind the rotor, the system uses the relationship between rotor performance parameters and wind conditions to estimate the actual wind speed in front of the rotor, thereby avoiding the distortion caused by rotor impact.
Solution Approach 2:
The patent replaces direct mechanical wind speed measurement with a computational estimation approach. By substituting the direct measurement system with a calculation-based system that processes rotor speed and pitch angle data, the method eliminates the need for complex physical measurement devices while achieving more accurate wind speed determination.
2Measurement precision
If wind speed is measured at a single point, then the measurement is simple, but it does not reflect variations in wind speed across the rotor area
Solution Approach 1:
The patent makes the rotor speed and pitch angle measurements serve multiple functions. These parameters not only control the turbine operation but also simultaneously provide the basis for estimating wind speed across the entire rotor area, eliminating the need for separate measurement devices at multiple points.
Solution Approach 2:
The wind turbine's own operational parameters (rotor speed and pitch angle) are used to estimate the wind conditions. The system essentially measures itself by utilizing its performance characteristics as indicators of the wind environment, avoiding the need for external measurement infrastructure.
3Measurement precision
If pitch angle is used directly for wind speed estimation, then the calculation is simple, but the estimation is inaccurate for flexible blades due to blade torsion
Solution Approach 1:
The patent applies preliminary correction to the pitch angle by calculating and applying a torsion compensation value before using it for wind speed estimation. This preliminary adjustment accounts for the blade torsion effect in advance, ensuring that the pitch angle used in the estimation reflects the actual aerodynamic conditions at the blade elements.
Solution Approach 2:
The patent transforms the raw pitch angle parameter into a corrected pitch angle parameter by incorporating torsion compensation. This parameter transformation adjusts the pitch angle to reflect the actual effective pitch angle experienced by the blade elements, accounting for the torsional deformation that occurs under load.
Data Source
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AI summary
A method for estimating a wind speed at a wind turbine is disclosed, said wind turbine comprising a rotor carrying a set of wind turbine blades, each wind turbine blade having a variable pitch angle. A blade torsion contribution, representing torsion introduced in the wind turbine blades, is derived, based on an obtained rotational speed, ω, of the rotor, and an obtaining a pitch angle, θ, of the wind turbine blades. An adjusted pitch angle, θ', is calculated as a sum of the obtained pitch angle, θ, and the derived blade torsion contribution, and a wind speed, vest, is estimated, based on the obtained rotational speed, ω, and the calculated adjusted pitch angle, θ'. An accurate and reliable estimate for the wind speed is thereby obtained. The wind turbine may be controlled in accordance with the estimated wind speed, vest.