The most common types of wind turbine failure are turbine blades, generators, and gearboxes. Regular maintenance and inspections of wind turbines create challenges due to the remote locations of wind farms and the size and height of the turbines. During regularly scheduled maintenance, it can be difficult to access the massive rotor blades and evaluate the blade materials and the complex surface areas. New technologies like the use of drones for blade inspections are being used, which aids in the inspection process. However, without proper monitoring and maintenance, it can lead to component failure.
1. Blade Failure
As the demand for renewable energy grows, the wind industry is finding ways to boost the energy output of wind turbines. One way to increase energy from turbines is to increase the size of the rotor blades. Larger blades produce more power. Rotor blade arcs are now reaching up to 262 feet or 80 meters. With the sizes of blades increasing, it can put additional pressure on the structure and other components in the turbine. It is estimated that there are 3,800 incidents of blade failure each year. Common flaws to look out for include debonding, joint failure, splitting along fibers, gel coat cracks, and erosion. Contributing factors for blade failure include lighting strikes, material or power regulator failure, damage from foreign objects, and poor design. Blade failure is the most common failure in wind turbines and can lead to costly repairs and revenue lost from being shut down.
2. Generator Failure
The generator in a wind turbine is responsible for creating the electricity by converting mechanical energy into electrical energy. When the generator fails, no power is produced, costing the wind farm operator valuable revenue. There are several reasons why the generator can fail, including wind loading, weather extremes, and thermal cycling. Mechanical or electrical failure of the bearings, excessive vibration, voltage irregularities, and cooling system failures can lead to excessive heat and fire. Lastly, manufacturing or design faults, improper installation, lubricant contamination, and inadequate electrical insulation can also cause the generator to fail. A comprehensive maintenance and repair program will improve the reliability and longevity of the generator, avoiding costly shutdowns and unexpected repairs.
3. Gearbox Failure
While gearboxes are designed to meet the harsh operational conditions, most do not make it past ten years, falling short of their 20-year design lifespan. Each year there are approximately 1,200 gearbox failures. The bearings and gears make up 96 percent of the failing components within the gearbox. Some contributing factors of failure include dirty or water-contaminated lubrication, improper bearing settings, significant temperature fluctuations, improper or infrequent maintenance and servicing, and transient loads leading to sudden accelerations and load-zone reversals. When a gearbox fails, it is a costly incident. The gearbox is 13 percent of the overall cost of the turbine and is an expensive component to replace. Also, during replacement, the turbine will be taken offline for as little as a few days, or it could be up to a couple of months based on the availability of parts. Any time the turbine is not spinning, means it is not generating revenue.
Preventing Wind Turbine Failures
Preventive maintenance is one way to reduce the chance of failures in a wind turbine and extend their lifetimes. Monitoring temperatures, vibration signatures, and structural integrity of components help to anticipate possible failures. Understanding the root cause of the different types of failure can ultimately lead to improvements in the design and increase the reliability of the components. Furthermore, creating reliability models of the various components assist in managing risk and improving maintenance planning. When turbine components fail, they require unscheduled repairs and downtime, resulting in lost revenue. By minimizing wind turbine failure risks, you avoid costly shutdowns.