Planning Considerations for Wind Turbine Maintenance

As your wind farm ages, asset downtime will become increasingly apparent due to component failure. This makes it important for owners and operators to ensure that their assets are maintained to a good standard and as efficiently as possible to minimise lost revenue.

Effective planning is key to ensuring that your assets are adequately maintained, under correct weather conditions, and at appropriate wind speeds. Planning ahead ensures maintenance activities are not prolonged due to weather delays or other external factors, resulting in unnecessary asset downtime and lost production.

When planning both preventative and reactive maintenance on a wind turbine, there are several factors to consider for each specific type of activity. A brief overview of each type of maintenance activity can be found below.

Blade Inspections and Repairs

When carrying out blade inspections and repairs on a wind turbine, there are many factors to consider to ensure the effective and efficient completion of these works.

Traditionally, blade work is only carried out between April and August when humidity levels are at the lowest and temperature levels are within tolerance. This ensures that the resins, adhesives, and other chemicals are adequately cured.

Curing can be defined as the act of these items becoming fully hardened. Whenever you apply these types of chemicals to a solid material, it goes through a chemical process of bonding to the surface. Until it has fully bonded and hardened, these chemicals are not yet cured and that means that they are not ready to withstand the external influences that wind turbine blades are exposed to daily.

Blade work is also traditionally carried out during these months, as the wind speeds within these months tend to be lower. This allows the necessary work to be carried out without delays due to high wind speeds. It also minimises losses.

Wind Turbine Inspections

Wind turbine inspections are usually carried out in months with lower wind speeds as not to adversely affect power generation. Typically, this type of inspection would be carried out between April and August, when production is slightly lower.

Carrying out wind turbine inspections within these periods allows defects to be highlighted and addressed whilst there is less demand on the main components of the wind turbine. In the periods with increased wind speeds, the demand on these components increases exponentially, increasing the likelihood of component failure and asset downtime proportionally.

The importance of regular wind turbine inspection is that it allows all involved parties to be assured that the quality of the turbine and its components, condition of maintenance standards, and performance are optimum.

A thorough inspection must be carried out, together with a robust defect report submitted, to ensure:

• The condition of the wind turbine and its components
• The performance of any repairs that need to be conducted
• Early fault detection / Pre failure identification

Preventative Maintenance

The standard preventative maintenance schedule, suggested by manufacturers, is to usually have two maintenances carried out per year.

The first is known as semi-annual maintenance, where all grease cartridges and pumps are re-filled, and all oil reservoirs are topped up ensuring that moving parts are adequately lubricated. This is to prevent degradation, which may result in component failure.

The second maintenance is known as annual maintenance. This occurs 6 months from the semi-annual maintenance. Grease cartridges and/or pumps are filled during the maintenance. During this maintenance, all other routine tests and updates are carried out, including software updates, retightening and extensive functional checks.

The commissioning date of a turbine determines when each maintenance is carried out. Semi-annual maintenance should be carried out no more than 6-months from the date of commissioning. Annual maintenance should take place no longer than 12 months from the date of commissioning, although the period of these maintenances can be brought forward to ensure maintenances is carried out during the most favourable weather conditions. These maintenances should not be delayed as they may lead to asset downtime associated with inadequate levels of maintenance.

To find out the benefits of reliability-centered maintenance for your wind turbines, download our latest paper.

Email us to see how we can assist you with wind turbine and blade inspections, as well as implementing reliability-centered and preventative maintenance.

Written by Jake Mason, Engineering Manager