Wind Turbine Blade Load Control via Tip Acceleration
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Solution Overview
Problem
Existing wind turbine load detection systems are delayed in responding to transient loads near the tip of rotor blades due to turbulence or gusts, allowing blades to operate above their maximum strain limit before protective actions can be taken, potentially causing damage and reducing energy capture.
Innovation Solution
The method involves measuring loads at the root end and acceleration at the tip of the rotor blade, using this data to predict and control wind turbine configurations to maintain loads below a predetermined threshold, allowing for quicker reaction to wind conditions and optimizing energy capture while preventing fatigue.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If protective actions are taken when the safety strain limit is reached, then the rotor blades are protected from damage, but energy capture is reduced during steady high winds without gusts or turbulence
Solution Approach 1:
The system performs preliminary action by detecting acceleration at the blade tip before the load propagates to the root and before the safety strain limit would be reached. This early detection allows the control system to prepare protective actions in advance, but only when actually needed for transient loads, thereby avoiding unnecessary protective actions during steady high winds and maintaining energy capture.
Solution Approach 2:
The system dynamically adjusts the protective threshold based on real-time acceleration measurements. Instead of using a fixed safety strain limit, the system modulates the effective threshold dynamically - lowering it when transient acceleration indicates an incoming gust, and maintaining it at higher levels during steady conditions. This dynamic adaptation resolves the contradiction by making protection adaptive rather than static.
2Strength
If the pitch of the rotor blades is varied to reduce wind loading, then stresses in the rotor blades are reduced, but the overall energy capture by the wind turbine is reduced
Solution Approach 1:
The system performs preliminary action by detecting acceleration at the blade tip before the load propagates to the root and before the safety strain limit would be reached. This early detection allows the control system to prepare protective actions in advance, but only when actually needed for transient loads, thereby avoiding unnecessary protective actions during steady high winds and maintaining energy capture.
Solution Approach 2:
The system dynamically adjusts the protective threshold based on real-time acceleration measurements. Instead of using a fixed safety strain limit, the system modulates the effective threshold dynamically - lowering it when transient acceleration indicates an incoming gust, and maintaining it at higher levels during steady conditions. This dynamic adaptation resolves the contradiction by making protection adaptive rather than static.
3Measurement precision
If load sensors are fitted at the root end of the rotor blades, then the stress experienced by the rotor blades can be determined, but there is a time delay in detecting transient loads before they propagate to the root
Solution Approach 1:
The system introduces an intermediary measurement point at the blade tip using an accelerometer. This intermediary sensor detects transient loads at their origin before they propagate to the root, providing early warning of incoming gusts. The tip acceleration measurement acts as a mediator that bridges the time gap between load application and root detection, enabling the control system to react before the full load reaches the root.
Solution Approach 2:
The system replaces the purely mechanical stress propagation-based detection with a hybrid approach that includes inertial sensing (accelerometry). Instead of relying solely on mechanical stress waves traveling through the blade structure to reach the root sensors, the system uses accelerometers to directly measure the dynamic acceleration caused by transient loads at the tip, providing immediate detection without waiting for stress propagation.
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 enables wind turbines to operate safely near the load threshold, maximizing energy capture across varying wind conditions while reducing the risk of blade damage from excessive loads.
Implementation Method 1
measuring an acceleration at a location on the rotor blade outboard from the root end, the acceleration being caused by transient loads acting on the rotor blade
Implementation Method 2
measuring load at a root end of the rotor blade; The measured strain on the rotor blades can be used to determine the stress experienced by the rotor blades through predetermined stress-strain relationships
Data Source
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AI summary
Improvements Relating to Wind Turbines A wind turbine apparatus and a method of operating said wind turbine to maintain the load on the rotor blade below a predetermined threshold level is provided. The method comprises: measuring load at a root end of the rotor blade; measuring an acceleration at a location on the rotor blade outboard from the root end, the acceleration being caused by transient loads acting on the rotor blade; and controlling the wind turbine based upon the measured load and the measured acceleration to maintain the load on the rotor blade below a predetermined threshold level.