Wind Turbine Blade Accelerometer Differential Monitoring

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Solution Overview

Problem

Existing wind turbine blade monitoring technologies, such as strain gages and optical fibers, face limitations including limited stress cycles, breakage, and increased complexity and cost, while accelerometer-based systems require careful calibration and are prone to common mode errors.

Innovation Solution

A wind turbine with two accelerometers mounted at different radial positions on the blade, allowing for reliable monitoring by generating a signal based on both acceleration values to compensate for common mode errors and varying pitch angles, and using differential acceleration to detect blade conditions like fractures or icing.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Measurement precision

If strain gages are embedded in the blade structure for monitoring, then local strain can be estimated, but the sensor has limited stress cycles and replacement is cumbersome and time consuming

Engineering Contradiction:

Improvelocal strain estimationVSAvoidsensor durability

Core Design Contradiction:

Measurement precisionVSReliability

Solution Approach 1:

The patent replaces mechanical strain gages with optical fiber sensors that use light transmission properties to detect blade deformation. This substitution eliminates the mechanical contact and stress cycle limitations of traditional strain gages, providing a more reliable and durable monitoring solution that does not require embedding in the blade structure.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

Solution Approach 2:

The patent uses optical fibers to create an optical copy or representation of the blade's deformation state by measuring changes in light transmission. Instead of directly measuring mechanical strain with physical gages, the system captures the deformation information through optical properties, enabling non-contact and more durable monitoring.

Inventive Principle:

Principle #26Copying

2Measurement precision

If optical fibres are embedded in the blade structure for monitoring, then blade deformation can be estimated, but the fibers are prone to breakage and embedding adds to complexity and cost

Engineering Contradiction:

Improveblade deformation estimationVSAvoidblade manufacturing complexity

Core Design Contradiction:

Measurement precisionVSDevice complexity

Solution Approach 1:

The patent replaces the mechanical embedding of optical fibers within the blade structure with a surface-mounted or externally attached configuration. This substitution eliminates the complex embedding process and associated costs while maintaining the ability to measure blade deformation through optical transmission properties, thereby reducing manufacturing complexity.

Inventive Principle:

Principle #28Mechanics substitution (Replace mechanical system)

3Measurement precision

If accelerometers are mounted on the blade for monitoring, then out-of-plane deflection can be measured, but the system requires careful calibration and is prone to common mode errors

Engineering Contradiction:

Improveblade deflection measurementVSAvoidcalibration complexity

Core Design Contradiction:

Measurement precisionVSEase of operation

Solution Approach 1:

The patent uses optical fibers to create an optical measurement system that copies the blade's deformation state through light transmission changes. This optical copying method inherently references the blade's actual position and orientation, eliminating the need for separate calibration procedures required by accelerometers and reducing common mode errors related to mounting and orientation.

Inventive Principle:

Principle #26Copying

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 enhances the accuracy and reliability of blade monitoring, reduces the impact of common mode errors, and simplifies the monitoring process by using differential acceleration, enabling early detection of blade issues and improving operational control.

Implementation Method 1

optical fibres have been embedded in the blade structure for estimating blade deformation from a change in transmission properties of the fibers as they are stretched during blade deformation

Methodology Applied

Scientific EffectOptical fiber transmission property change: Optical Fibre

Data Source

PatentUS8951011B2Wind turbine and a method for monitoring a wind turbine

Publication Date: 2015.02.10 VESTAS WIND SYSTEMS AS

AI summary

According to the inventive concept, there is provided a wind turbine with at least one blade. The wind turbine comprises a first accelerometer mounted at a first radial position of the blade and being adapted to determine a first acceleration value, and a second accelerometer mounted at a second radial position of the blade different from the first radial position, and the accelerometer being adapted to determine a second acceleration value. The wind turbine further comprises a controller adapted to generate a signal based on said first and second acceleration values. There is also provided a method for monitoring a blade of a wind turbine.