Wind Turbine Pitch Control Using Tower Measurements for Whirling Modes
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Solution Overview
Problem
Existing wind turbine systems face challenges in mitigating edgewise blade vibrations, particularly whirling modes, which can lead to increased wear and damage, and current methods relying on blade load sensors are inadequate when one or more sensors fail or are unavailable.
Innovation Solution
A controller that uses tower or nacelle acceleration signals to determine orthogonal components indicative of whirling modes, applying a second-order generalized integrator 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 edgewise blade vibrations can be mitigated, but the system becomes vulnerable to sensor failure and requires complex sensor installation
Solution Approach 1:
The patent uses tower acceleration measurements as an intermediary indicator to infer blade edgewise vibrations. Instead of directly measuring blade loads with complex sensors, the system measures tower motion which correlates with blade vibrations, thereby simplifying the measurement system while maintaining control effectiveness
Solution Approach 2:
The patent replaces mechanical blade load sensors with a tower-mounted acceleration sensor system. By substituting direct blade measurement with tower response measurement, the system reduces mechanical complexity and sensor vulnerability while achieving the same control objective through dynamic relationship analysis
2Measurement precision
If blade load sensors are installed on each rotor blade, then accurate individual pitch control is achieved, but the manufacturing and installation complexity increases significantly
Solution Approach 1:
The patent merges the measurement function from multiple distributed blade sensors into a single tower-mounted acceleration sensor. By combining measurement locations and functions, the system achieves comparable measurement precision while dramatically simplifying installation and manufacturing requirements
Solution Approach 2:
The tower acceleration sensor serves multiple functions: it monitors tower vibrations, infers blade edgewise vibrations, and provides input for individual pitch control. This multi-functionality eliminates the need for dedicated blade load sensors, improving ease of manufacture while maintaining measurement precision
3Reliability
If the wind turbine operates in safe mode with derated power, then component damage is prevented, but energy capture efficiency decreases
Solution Approach 1:
The patent implements continuous feedback control using tower acceleration measurements to actively damp edgewise vibrations. This real-time feedback mechanism allows the system to maintain safe operation under vibration conditions without requiring derated power mode, thereby preserving energy capture efficiency while ensuring component safety
Data Source
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.