Wind Turbine Tip Clearance Control Using Dynamic Pitch Adjustment
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Solution Overview
Problem
As wind turbines with longer blades face challenges in tip clearance due to extreme environmental conditions and increased flexibility, existing methods struggle to ensure reliable and stable operation, particularly during wind shear, gusts, and turbulence, which can lead to tower strikes.
Innovation Solution
A tip clearance control (TCC) method that estimates tip clearance using a combination of pitch angles, generator speed, torque, and blade load values, employing a double PI control module to generate control commands that adjust pitch settings and ensure a minimum safety clearance, utilizing strain gauges and fibre optic sensing for accurate measurements.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If longer blades are used to extract more energy from wind, then energy extraction capability is improved, but tip clearance becomes larger and risk of tower strike increases
Solution Approach 1:
The patent implements a dynamic tip clearance control system that continuously adjusts pitch angles based on real-time blade deflection measurements. The system uses a tip clearance estimator to predict clearance values and a controller to dynamically modify pitch commands, making the blade system adaptable to changing wind conditions and maintaining safe clearance despite longer blade lengths
Solution Approach 2:
The patent employs a closed-loop feedback mechanism where strain gauges or accelerometers measure blade out-of-plane deflection, the controller processes this information to determine tip clearance risk, and corrective pitch actions are applied. This feedback loop enables continuous monitoring and adjustment to maintain reliable operation with longer blades
2Adaptability or versatility
If blade flexibility is increased to handle extreme environmental conditions, then adaptability to wind shear and gusts is improved, but probability of hitting the tower increases
Solution Approach 1:
The patent applies preliminary action by proactively adjusting pitch angles before extreme conditions cause excessive blade deflection. The tip clearance estimator predicts potential clearance violations, and the controller pre-modifies pitch commands to bend the rotor plane away from the tower, preventing tower strikes before they occur
Solution Approach 2:
The closed-loop feedback system continuously measures blade deflection and adjusts pitch angles in real-time to compensate for flexible blade behavior under wind shear and turbulence, maintaining safe tip clearance despite increased blade flexibility
3Reliability
If active pitch control is applied to reduce tip clearance, then tip clearance safety is improved, but system complexity increases
Solution Approach 1:
The patent integrates tip clearance control functionality into the existing pitch control system, making the controller perform multiple functions: normal pitch regulation, tip clearance estimation, and active tip clearance control. This multi-functionality approach reduces overall system complexity by avoiding separate dedicated hardware for tip clearance control
Data Source
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AI summary
A method of tip clearance control (TCC)(1000) and a wind turbine generator (1) are disclosed, the wind turbine generator has a rotor with at least one blade (5) rotating relatively to a tower (2) and with a tip clearance (8) between a blade tip (7) of at least one blade and the tower, the method comprising: measuring (1100) a set of operational values (110) and a set of blade load values (150); estimating (1200) the tip clearance (210) as a function of the set of operational values and the set of blade load values; generating (1300) a control command (310) from the estimated tip clearance (210). A computer program product (400) and a wind turbine generator control system (300) are also disclosed.