Wind Turbine Pitch Control with Estimated Missing Blade Load Signal
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Solution Overview
Problem
Existing wind turbine systems face inefficiencies when one blade load sensor becomes unavailable, leading to derated operation and reduced energy capture due to the reliance on individual pitch control based on all three sensor measurements.
Innovation Solution
A rotor control system that constructs combined load signals using available blade load signals, applies a high pass filter, and transforms these signals into an intermediate coordinate frame to estimate the unavailable signal, allowing for accurate pitch control even with two available sensors, using coordinate transformations like Clarke and Coleman transformations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the wind turbine operates in safe mode with derated power when one blade load sensor is unavailable, then the turbine ensures operation within design load envelope, but the energy capture is negatively impacted
Solution Approach 1:
The patent introduces an intermediary estimation process that uses the two available blade load sensor signals to reconstruct the third unavailable signal. By applying coordinate transformations (such as Clarke or Coleman transformations) and high-pass filtering, the system creates a virtual third sensor signal that allows the individual pitch control algorithm to continue functioning with all three signals present, thereby maintaining full power operation without compromising safety
Solution Approach 2:
The patent creates a copy or replica of the unavailable blade load sensor signal by estimating it from the two available sensors. The estimation process generates a virtual signal that mimics what the third sensor would have measured, allowing the control system to operate as if all three sensors are functional. This copying approach enables the turbine to maintain normal operation and energy capture while ensuring load safety
2Reliability
If individual pitch control relies on all three blade sensor measurements, then load reduction control is effective, but the system cannot operate normally when one sensor becomes unavailable
Solution Approach 1:
The patent implements a beforehand cushioning mechanism by preparing an estimation algorithm that activates when a sensor failure occurs. The system is designed in advance to handle sensor unavailability through the use of high-pass filtering and coordinate transformations, creating a buffer that prevents system shutdown. This prior preparation ensures that the individual pitch control can maintain load reduction effectiveness even when one sensor becomes unavailable
Solution Approach 2:
The patent changes the parameters of the control system by transforming the available sensor signals through coordinate transformations (such as converting from blade-specific coordinates to rotating reference frame coordinates). This parameter transformation allows the system to reprocess the two available signals into a format that enables estimation of the third signal, thereby maintaining adaptability and continued operation with modified signal parameters
Data Source
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AI summary
The present invention relates to pitch actuation of pitch-adjustable rotor blades of a three-bladed wind turbine in a situation where one blade load sensor is unavailable. Based on blade load signals (L1, L2, L3) and an availability signal (v1, v2, v3) for each of the blade load signals, combined load signals are constructed based on the available blade load signals. The combined load signals are determined based on application of a high pass filter to the blade load signals and a transform (T1) of the blade load signals to an intermediate coordinate frame, wherein, in the transform, the unavailable blade load signal is replaced with an estimated signal. A control action (CA) is performed using the combined load signals, and the resulting pitch modification signals (Δθ1, Δθ2, Δθ3) are applied to the pitch actuator.