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BladeSave: Innovative New Wind Turbine Blade Monitoring

TWI was part of a consortium of companies working on the BladeSave Project, to develop a condition monitoring system for wind turbine blades.

The partners, Renewable Advice (coordinator), EWT (end user, wind turbine owner), ASSIST (software, website), Smart Fibres (hardware) and TWI pooled our expertise to reduce the risks associated with blade failure while also contributing to the competitiveness of global wind energy. 

The consortium united the partners’ expertise in structural health monitoring, fibre optic sensing technologies and management software to create a comprehensive system for monitoring, repair and management of wind turbine blades.

Challenges of Wind Turbine Monitoring

Although wind energy is one of the fastest growing markets for world energy, turbine blades are susceptible to fatigue failure and environmental effects. Cracks in the blades, if left unattended, will grow and propagate under fatigue loading, which will eventually lead to blade failure and a costly replacement.

Condition monitoring is the most effective way to mitigate against this problem. By continuously monitoring the blades, defects such as blade imbalance, blade damage and ice accretion can be detected at an early stage and quickly fixed for a low cost.

BladeSave aims to increase the average annual availability of wind turbines from 95% to 98-99% by optimising maintenance to maximise component life spans and reduce unscheduled repair, replacement and breakdown.

A Fusion of State-of-the-Art Technologies

BladeSave is a fusion of structural health monitoring with a blade management software to link the data and provide a comprehensive solution for wind turbine management. 

The structural health monitoring is carried out using fibre optic systems, namely ‘Smartscan’ and ‘Smartsonic’, which provides multi-sensing capabilities, including strain, vibration and acoustic emission. The data acquisition system has been developed to dynamically measure the root loading of rotor blades during their operating lifetime. The data from this system is pre-processed onsite to extract key parameters, which are then coupled with a cloud-based blade management software called ‘WindManager,’ to create a risk matrix to evaluate the blades on a 5-grade scale, hence providing a joined-up approach to monitoring, management and repair.

Fig 1. Edge Test Set-Up
Fig 1. Edge Test Set-Up

BladeSave Vs Conventional Blade Monitoring

Conventional methods of blade monitoring use strain gauges to measure strains and thereby the loads in the blade. While this can regulate blade pitch control and reduce loads, these systems can only detect a deviation in strain once the crack is sufficiently large, by which point a major structural repair or even a catastrophic failure is imminent.

BladeSave is able to ‘listen’ to the inaudible sound and vibrations produced by the structure, detecting high frequency information that are indicative of a crack forming and propagating. This ability to detect a defect earlier means that repairs are smaller and turbine downtime is minimised.

With many operators capping their repair budgets, the BladeSave system means that maintenance budgets are able to stretch much further.

 

Outcomes and Next Steps

Using Fibre Bragg Grating (FBG) sensors, BladeSave offers an innovative design and multi-sensing capabilities. As a result, the system’s immunity covers static electricity, EMI noise and lightning. This robust, all-optic sensing design is linked with the blade management software to provide a comprehensive solution for wind turbine blade monitoring, repair and management. The joint use of fibre optic hardware and WindManager makes the system’s health monitoring transparent for the end user with a risk matrix evaluating the blade health.

The technical nature of BladeSave means that it can accommodate differences in power rating in turbines by modifying the length of the optic fibres. This means that the system to accommodate the range of power ratings (typically from 0.01 to 7 MW) so it can be used with any wind turbine.

The system was tested with the installation of strain patches, accelerometers and acoustic emission sensors inside blades at a EWT’s wind turbine in the Netherlands. BladeSave’s data acquisition and processing units were installed in cabinets in the hub of the turbines and tested for over three months. The system sent back live data to show its effectiveness in delivering ongoing long-term operational profiles.

There is a final development to be completed to qualify for the Technology Readiness Levels. TWI is due to undertake destructive testing on a wind turbine blade fitted with the BladeSave system. This will allow us to compare BladeSave to a commercial system using controlled cyclic loading to simulate blade cracking and propagation. The system is expected to demonstrate the capability to detect cracks in the early stages and show how it can support maintenance decision making.

 

The BladeSave project has received funding from the European Union’s Horizon 2020 programme under grant agreement No 760353.

Fig 2.
Fig 2.
Avatar Linghao Zhou Project Leader - Condition and Structural Health Monitoring

Linghao has an MSc in Electrical Engineering from the University of Adelaide and a Ph.D. from London South Bank University in Rotating Machinery Diagnosis. He has published numerous journal papers and presented in national and international conferences. Linghao has been actively involved in multiple European funded projects, which aimed to develop innovative condition monitoring systems for critical rotational and/or structural assets. Linghao is working towards professionally registering as a Charted Engineer.

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