Wind Turbine Pitch Control Using Tower Signals for Whirling Modes
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Solution Overview
Problem
Existing wind turbine systems face challenges in effectively mitigating edgewise vibrations, particularly whirling modes, which can lead to blade damage, as they often rely on blade load sensors that may fail or be unavailable, necessitating derating and inefficient operation.
Innovation Solution
A controller that uses tower or nacelle acceleration signals to determine orthogonal components indicative of whirling modes, employing a second-order generalized integrator (SOGI) and inverse m-blade coordinate transformation to generate pitch reference offsets for rotor blades, enabling effective whirling mode control without relying on blade load sensors.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If blade load sensors are used for individual pitch control, then whirling mode mitigation is effective, but system complexity and cost increase due to sensor installation and potential sensor failure
Solution Approach 1:
The invention extracts the vibration measurement function from blade-mounted sensors and relocates it to tower-mounted acceleration sensors. This removes the need for complex blade sensor installation while maintaining the ability to detect edgewise vibrations and whirling modes through tower response measurements.
Solution Approach 2:
The tower acts as an intermediary structure that transmits blade vibration information to sensors mounted on it. By measuring tower acceleration responses, the system indirectly captures blade edgewise vibration characteristics without requiring direct blade sensor attachment.
2Measurement precision
If blade load sensors are installed for vibration detection, then measurement precision improves, but weight and cost of the wind turbine increase
Solution Approach 1:
The measurement function is extracted from the blade structure and relocated to the tower, eliminating the need for additional blade sensors. This removes the associated weight penalty while maintaining measurement capability through the tower's structural coupling to the rotor system.
3Reliability
If derating is applied when blade sensors fail, then operational safety is ensured, but energy capture efficiency decreases
Solution Approach 1:
The invention creates a redundant measurement system using tower acceleration sensors that copies the functional capability of blade load sensors. This alternative measurement path allows the control system to maintain whirling mode mitigation and avoid derating when blade sensors fail, preserving energy capture efficiency while ensuring operational safety.
4Device complexity
If tower acceleration sensors are used instead of blade load sensors, then device complexity and cost are reduced, but measurement precision for blade vibrations may deteriorate
Solution Approach 1:
The tower serves as a mechanical intermediary that couples blade vibrations to the measurement system. The structural connection between blades and tower transmits vibration information, allowing tower-mounted sensors to detect blade edgewise motions without requiring direct blade sensor attachment.
Solution Approach 2:
The invention replaces direct mechanical blade sensor attachment with indirect tower-based measurement. This substitution simplifies the mechanical installation while using signal processing to extract blade vibration characteristics from tower response data.
Data Source
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AI summary
The invention relates to adjusting pitch of rotor blades of a wind turbine. An acceleration signal is received from a wind turbine acceleration sensor and is indicative of side-to-side motion of the wind turbine tower. A first component in a fixed coordinate frame of the wind turbine is determined based on the received acceleration signal. The first component is indicative of a whirling mode of the wind turbine caused by edgewise vibrations of the rotor blades. A second component is generated based on the first component and is orthogonal to the first component. A control action is applied to obtain first and second control components for mitigating the whirling mode. An inverse m-blade coordinate transformation is applied to the first and second control components to obtain pitch reference offset values in a rotor coordinate frame of the wind turbine, which are used to adjust pitch of the rotor blades.