Extreme cold start-up validation of a wind turbine gearbox by the use of a large climatic test chamber
Wind turbines are more frequently installed in remote areas, where very often profitable wind conditions makes those sites attractive to implement wind energy parks. On the other hand, such locations have to deal with extreme inhospitable climatic conditions: extreme cold and/ or hot temperatures, strong winds and gusts, high humidity, ice and/or snow, salty environment (in case of the offshore market).
These inhospitable locations form a huge challenge for the machine itself and maintenance and repairs works in such circumstances can be challenging. In some cases repair works have to be postponed because of bad environmental conditions and thereby noticeably affects the turbine availability and its business case. For this reason, wind turbines and its components need to be designed and validated to meet the capability of surviving and operating in such extreme conditions. OEM’s and component suppliers are more and more aware of the need to perform advanced validation tests in order to substantiate confidence in its designs, and to increase the reliability and robustness of their products in such inhospitable environments.
-40°C to +60°C
Siemens Gamesa, a leading manufacturer of multi-MW wind turbine gearboxes is also aware of the benefit of a dedicated validation processes. For the part of extreme cold temperatures and hot climate validation tests it teamed up with OWI-Lab.
The test bench is used to verify the capability of the gearbox to withstand a shutdown event and subsequent return into service in extreme cold climate conditions (cold soak test). The same test bench can also be used to validate the cooling performance of the gearbox in hot climatic conditions.
Potential failure modes of a gearbox at extreme cold or hot temperatures include:
- Lubricants become viscous and too stiff due to extreme cold, putting exceptional load on the pumping equipment and other auxiliaries mounted on a wind turbine gearbox system.
- Rotating elements in the gearbox can be at risk because of insufficient lubrication and/or differential thermal expansion of sub components.
- Lubricants can become more or less viscous which effects the oil flow in bearings and raceways.
- Cooling system can experience overheating problems during extreme heat.
- Long cold start-up runs and its negative effect on energy yield.
- Low temperatures effect materials (plastics, metals, rubbers) and cause brittle fracture of materials (sealings, cables, gears,…)
The potential failure modes illustrate the requirement for qualitative engineering of the lubrication mechanism, thermal management system and appropriate control strategy in case of (extreme) cold start-up events. Validating these systems in a controlled environment has been performed by Siemens Gamesa together with OWI-Lab.