Wind Turbine Pitch System Runaway Load Mitigation
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Solution Overview
Problem
Wind turbines face challenges in distinguishing between blade stuck and blade run-away conditions during pitch system failures, leading to increased loads due to incorrect feedback from a faulty pitch system encoder.
Innovation Solution
A method and system that utilize sensors and a turbine controller to determine the actual and estimated rotor loading, calculating the difference to identify a blade run-away condition, and implement corrective actions based on the type of defective blade condition, using sensors like proximity, inductive, or LIDAR sensors to differentiate between blade stuck and run-away scenarios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the pitch system encoder fails, then the controller cannot determine whether the rotor blade is moving or not, but the controller continues to send pitch rate commands which may cause blade run-away condition
Solution Approach 1:
The patent implements a feedback mechanism where the turbine controller receives pitch movement feedback from the pitch controller and compares it with expected pitch position changes. When the encoder fails, the feedback shows no pitch movement despite continuous pitch rate commands, allowing the controller to detect the fault condition and differentiate between blade stuck and blade run-away scenarios based on the discrepancy between commanded and actual pitch positions.
Solution Approach 2:
The patent introduces an intermediary comparison mechanism that mediates between the pitch controller commands and the encoder feedback. By comparing the pitch position command from the turbine controller with the actual pitch position feedback from the pitch controller, the system can detect when the encoder is providing incorrect feedback and infer the actual blade state through this intermediary comparison process.
2Speed
If the controller increases speed reference to reach pitch position command, then the pitch motor speeds up, but this produces blade run-away condition towards power or feather
Solution Approach 1:
The patent applies preliminary action by having the turbine controller continuously monitor and compare pitch position commands with actual pitch position feedback before the blade run-away condition fully develops. When the encoder fails, the controller detects the discrepancy between commanded and actual positions in advance, allowing it to identify the blade run-away condition early and implement corrective actions before excessive speeds and loads occur.
3Loss of information
If the pitch controller cannot determine blade movement due to encoder failure, then feedback becomes frozen, but the turbine controller needs to differentiate between blade stuck and blade run-away scenarios
Solution Approach 1:
The patent transitions from relying solely on the single dimension of encoder feedback to using multiple dimensions of information for blade condition detection. By comparing pitch position commands, pitch rate commands, and actual pitch position feedback across different time intervals and analyzing the relationships between these parameters, the system creates additional diagnostic dimensions that enable differentiation between blade stuck and blade run-away conditions even when the encoder feedback is frozen or incorrect.
Data Source
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AI summary
A method for identifying a blade run-away condition in the event of a pitch system failure of a rotor blade of a wind turbine includes determining, via one or more sensors, an actual rotor loading of the wind turbine. The method also includes determining, via a turbine controller, an estimated rotor loading of the wind turbine based on at least one of one or more operating conditions of the wind turbine or one or more wind conditions of the wind turbine. Further, the method includes determining a difference between the actual rotor loading and the estimated rotor loading. The method also includes determining whether the blade run-away condition is present based on the difference. The method may also include implementing a corrective action that mitigates loads caused by the blade run-away condition.