Operations and maintenance costs dominate the balance sheets of wind farms, and more so when the maintenance is unscheduled. That was the opening comment from an industry consultant at a recent O&M conference. His point was that wind farms run on thin margins and with more than half of the national fleet out of OEM warranty, maintenance costs can only increase. Hence, it pays to find ways to trim operating costs.

That search begins after a turbine leaves warranty, when either an independent survice provider or service firms affiliated with the OEM can be called for maintenance. This magazine recently conducted an informal survey that showed no preference towards one or the other. Still, a few O&M trends are visible. They include more confidence in condition monitoring, growth of predictive maintenance, optimization to site and turbine, and going beyond repairs to offer improvements.

Condition monitoring is a way to keep tabs on power-production equipment mounted on 60 to 100-m towers and often on wind farms in remote locations. Condition monitoring works in part with vibration sensors on main bearings, gearboxes, and generators that send signals to a monitoring station that can be many miles away. People monitoring the turbines could be responsible for several wind farms.

Analysis software – Fast-Fourier Transform – associates a frequency or rpm with a vibration amplitude, so it’s possible to nearly pinpoint an ailing component. One frequent contributor to this magazine shows how with the right diagnostics, a failing bearing can be spotted quickly without months of trend data. Because bearings generally do not fail catastrophically, their vibration amplitude can be tracked as it rises, and the bearing replaced on a schedule.

The key to success for a condition monitoring program is how it is implemented and used to maintain the turbine. Success requires discipline within an organization to implement an effective CMS strategy.

Condition monitoring is leading to a predictive capability that is beginning to exhibit an industry-wide drop in unforeseen events. Expect to hear the term “big data” more often in the discussion of predictive maintenance. A few companies here have written algorithms that sift through the mountains of data generated by SCADA systems to make predictions.

Also, an O&M cost model will help the turbine operator plan yearly operational expenditures, site staffing requirements, and spare part stock levels.

Another trend is for wind-farm owners to look to O&M crews for performance improvements in addition to repairs. For example, a recent idea for restoring performance to wearing blades comes from the aircraft industry and it’s getting attention in wind. Vortex generators (VGs) maintain smooth airflow across a wing or blade for longer periods, thereby increasing its lift. When used on a blade, VGs generally provide greater output for the wind turbine.

Recent contractual offerings between wind turbine OEMs and owners have centered on production. Additional analyses provide opportunity for greater production. Wind conditions at sites often don’t match those for which the wind turbine was originally designed. Initial sitings ensure the most energetic pad is within the design capability of the installed wind turbine. That means there is an opportunity to extract incremental production from the under-used wind turbines. WPE