1. Blade CMS can detect leading edge erosion both in severity and progression. Identifying opportunities for Annual Energy Production (AEP) improvements.
Leading edge erosion (LEE) compromises the aerodynamic performance of the blade and even moderate LEE can result in 1.8% AEP losses. Wind farms with particularly high storm events where water droplets, airbourne particles and high wind events can accelerate LEE. Blade CMS such as eologix-ping’s on-tower monitoring listens to the blade as it passes the tower to detect and damage that is producing noise (not aerodynamically good). Leading edge protection (LEP) can offer some longevity. In this instance Blade CMS can detect separation or damage to blade furntiture such as LEP or vortex generators.
2. Lightning strikes can not only damage blades but also poorly earthed power electronics.
Archaic lightning detection systems such as lightning cards require manual retrieval from the top of turbine and insertion into a lightning reader. This card only records the last strike, does not detect multiple strikes and is labour intensive. Automatic lightning strike notifications are given by on-tower systems such as eologix-ping using its in-built coil in order to register the current as it passes through the tower. If the blade itself is damaged during the lightning strike, the microphone will pick up the damage acoustically as the blade passes the tower.
eologix-Ping’s on-tower system is affixed by magnets to the wind turbine tower and send wireless signals periodically to alert wind farm owners to any damage.
3. CMS can lower the cost of insurance premiums through mitigation of catastrophic failure
The cost of insurance within wind for product and public liability cover is increasing as full scope service agreements look to pass risk back to wind farm owners. A number of insurance providers that are familiar with the liabilities of wind understand the risk mitigation benefits of CMS and offer premium reductions. At the end of the day it is about risk, if you can show that you can reduced the risk through early detection of failure then it is more likely that you are going to avoid a catastrophic payout.
4. Ensure a good quality blade repair with noise trending before and after a repair job.
Just as leading edge erosion will gradually become more noisy, when repairs are performed the acoustic trends come down. If repairs aren’t able to be finished or are not able to achieve a smooth finish then the acoustic signature of the blade will be high compared to others on the same WTG and others on the wind farm. This quality assurance is useful when managing external blade repair contractors.
Blade repair is an art performed in a dynamic environment suspended 50m up in the air. Quality can vary.
5. The earlier you catch a blade repair the cheaper it is.
Category 5 blade repairs can exceed £50k/blade so the earlier you catch the damage the cheaper the repair. Just like welding a classic car, the more rust that you have to cut out, fewer panels have to be made, fewer hours etc. If the blade repair is too far gone it may have to be craned down and covered in order to make a good quality repair. For older wind turbines, where the available of spare blades is limited, it pays to look after the ones that you have.
6. Contractual arguments concerning force majeure are won and loss in the data. Typically the OEM holds all of the data so third party blade condition monitoring systems can help.
Typically the owner pays when “God did it” and for that reason the maintenance provider/OEM have a penchance for using it as a contractual dumping ground either to get out of paying for component replacement or availability guarantees. The old saying goes there is an insurance product for everything but this too has a cost. By proving that a failure wasn’t caused by lightning it can save money and manage risks on both sides. When making an insurance claim, there is usually a time limit of a number of weeks when you can make a claim against the damage caused by a strike. With manual systems often this claim window can be missed. eologix-ping’s system gives automatic alerts every 20 minutes straight to your inbox. This tells you the time of the strike and the amount of strikes that hit the turbines. The following days will allow you to determine whether there has been any blade damage from the strikes as the microphone picks up the damage as it passes the tower.
7. Annual inspections by drone, rope access or telescope lens can give very useful information on the condition of the blades. Usually done once a year the days in between can see damage that can go undetected for a year.
Continuously monitoring blade health can allow you to track gradual or incremental changes in blade health. If the blades are damaged on the leading edges by rainfall, LEP separated or if the blades are struck by lightning, particularly at remote sites. The first you may hear of it is from a local resident. By continuously monitoring blade health as part of an overarching blade O&M strategy you can be alerted to damages faster and make more informed decision making.
8. Internal blade inspections are terrible. Access is limited, it’s periodic and you need special certification to enter the confined space.
It’s also greasy, there are probably loose blade bolts and its not too light in there either. The pic above is light as the blade had more cracks in it than a builder’s bum competition. Depending on the WTG and technician size there may also be a limited area of the blade root section that you can access. By instrumenting the blade root you can hear the cyclic cracking of the plastic and detect and track cracks.
9. Standard ice detection methodology is poor and can be improved through on-blade ice detection.
Ice build up on the blades stops the turbine either using anemometry or load sensors. This is supposed to prevent ice throw and overloading of drivetrain and structural wind turbine components. Give the nature of the sensors and their position this is sub-optimal and is usually complemented with a physical inspection to ensure that the wind turbine can be put back into operation safely. By instrumenting the blade with sensors that determine the environmental conditions on the blade you can accurately determine the amount of ice build up on the blade’s surface and as a result can restart the turbine without visual inspection. In a period of the year when the price of power, and wind speed is highest, availability is paramount. Controller integration is possible on some platforms to allow automatic stop/restart during ice events.
10. Failure to plan is preparation to fail. The logistics surrounding blade replacement are complex so the more warning you have of failure, the smoother the exchange will go and the cheaper the cost.
Cranes are expensive, especially when the weather delays major component replacement. It is not only easier to do major components in the summer, when the wind is lower, the downtime is also cheaper. Crane, tooling and labour availability for specialist services such as these are in high demand in short weather windows so it is easier to plan months in advance than it is when the blade has already failed and the wind turbine is potentially stopped whilst waiting for a crane or a replacement blade.
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