Torque Measurement in Wind Turbine Drivetrain Using Encoder Phase Shift
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Solution Overview
Problem
Existing methods for measuring torque in wind turbine drive trains are imprecise, which hampers load minimization, energy optimization, and active vibration damping.
Innovation Solution
The method involves using at least two incremental encoders positioned on different shafts of the drive train to measure periodic rotary signals, determining the phase shift between these signals, and correcting it with a no-load phase shift and stiffness factor through in-situ calibration to accurately calculate torque.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If two sensors measuring rotational speed are used to determine torque based on shaft twist, then torque measurement is achieved, but the measurement precision is insufficient for controlling the wind turbine
Solution Approach 1:
The patent replaces the mechanical twist-based measurement system with an optical/electromagnetic encoder system. Incremental encoders use optical or magnetic fields to detect rotational position and speed, providing higher precision torque measurement through phase shift analysis between two encoder signals, thereby resolving the insufficient precision problem while maintaining reasonable device complexity
Solution Approach 2:
The patent implements preliminary calibration procedures where zero-load phase shift and stiffness factor are determined before actual torque measurement. This preliminary action establishes reference values that compensate for system characteristics, significantly improving measurement precision without requiring complex real-time corrections during operation
2Measurement precision
If incremental encoders are used with in-situ calibration to improve torque measurement accuracy, then measurement precision improves, but the calibration process requires additional time and operational periods
Solution Approach 1:
The calibration system uses the wind turbine's own operational data and characteristics to perform self-calibration. By utilizing the turbine's existing motion patterns and measured responses during normal operation, the system determines zero-load phase shift and stiffness factor without requiring external calibration equipment or taking the turbine offline, thus minimizing time loss while achieving high measurement accuracy
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This approach provides a cost-effective and accurate torque measurement, enhancing wind power regulation, load minimization, energy optimization, and vibration damping within the drive train.
Implementation Method 1
at least two incremental encoders are positioned at two different locations on at least one shaft of the drive train, for example, on a rotor main shaft of a wind turbine, and each delivers periodic rotation signals when the shaft rotates
Data Source
Figure 1a~1b
Figure 2
Figure 3~4
AI summary
A method and a device for measuring the torque in the drivetrain (1) of a wind power plant is described, having at least two incremental encoders (7, 8) which are positioned at two different positions on at least one shaft (3) of the drivetrain (1) and which each supply periodic rotational signals, wherein the phases of the rotational signals are evaluated in order to detect a phase shift, and a torque of the shaft (1) is determined from the phase shift. The detected phase shift is corrected as a function of a zero load phase shift (Azero), using a rigidity factor K, wherein, in order to determine the zero load phase shift (Azero) and the rigidity factor K, in-situ calibration is carried out before and/or between the torque-determining processes. The in-situ calibration is performed at zero load of the wind power plant, i.e. below a rated rotational speed and with a generator torque equal to zero, and at the rated load of the wind power plant, i.e. at the rated rotational speed and with a generator torque greater than zero.