Wind Turbine Power Train Fatigue Damage Determination
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Solution Overview
Problem
Current methods for determining fatigue damage in wind turbine power trains are hindered by the difficulty in accurately obtaining input torque values at the low speed shaft, relying on capital-intensive experimental methods with strain gauges for each power train.
Innovation Solution
The application of a rainflow-counting algorithm to determine torque variations at the low speed shaft, combined with analytical calculations or finite element methods to establish relationships between torque and stress/strain, allowing for fatigue analysis and prediction through data matrices and SN/εN curves.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If experimental methods with strain gauges are used to measure torque at the low speed shaft, then measurement precision is improved, but device complexity and cost increase significantly
Solution Approach 1:
The patent replaces direct mechanical strain gauge measurements on the low speed shaft with an indirect calculation method using electrical measurements from the generator. By measuring electrical power and angular velocity at the generator and computing torque through mathematical relationships, the system avoids complex mechanical instrumentation while achieving accurate torque determination.
Solution Approach 2:
The patent introduces an intermediary calculation approach where torque at the low speed shaft is not measured directly but derived through intermediate measurements of electrical power and angular velocity at the generator, combined with rainflow-counting algorithm procedures to account for torque oscillations and fatigue effects.
2Measurement precision
If direct mechanical measurements are performed on each power train, then measurement precision is improved, but loss of time and productivity decrease due to capital intensive procedures
Solution Approach 1:
The method replaces time-consuming experimental mechanical measurements with rapid electrical measurements and computational processing. Electrical power and angular velocity data from the generator are readily available and can be processed quickly through rainflow-counting algorithms to assess fatigue damage, significantly improving productivity while maintaining measurement precision.
Solution Approach 2:
The patent establishes predetermined rainflow-counting algorithm procedures and fatigue assessment criteria in advance, allowing for rapid processing of torque data once electrical measurements are obtained. This preliminary preparation of assessment frameworks enables quick fatigue damage evaluation without requiring time-intensive experimental procedures for each assessment.
Data Source
AI summary
A method for determining the evolution of torque of at least one rotatable shaft and the resulting fatigue damage to different power train components is provided for design and/or maintenance operations in a wind turbine that comprises the steps of determining torque (Tg) at a high speed shaft of the power train; determining moment of inertia (Ig) at the high speed shaft; determining angular acceleration (αg) at the high speed shaft; and determining torque (Tr) at the low speed shaft of the power train through the formula Tr=(Tg−Ig αg)·i. A rainflow-counting algorithm may be applied to the value of the torque (Tr) at the low speed shaft for determining the number of cycles at ranges of torque for every torque mean value.