MRO Magazine

Sky-high challenge

Perched on hilltops and other especially windy sites across Canada, wind turbine generators (WTGs) are contributing 4,055 megawatts (MW) to Canada's power grid - enough to power over one million homes. Output is steadily rising as new projects...

February 1, 2011 | By Carroll McCormick

Perched on hilltops and other especially windy sites across Canada, wind turbine generators (WTGs) are contributing 4,055 megawatts (MW) to Canada’s power grid – enough to power over one million homes. Output is steadily rising as new projects come on line and as old WTGs are replaced with higher-output models.

The Canadian Wind Energy Association (CanWEA), source of the 4,055 MW figure, lists 111 wind farms and sites, and 2,309 WTGs – located everywhere but New Brunswick, the Northwest Territories and Nunavut. However, assuming a generous average 1.5 MW/turbine, the actual number of turbines could in fact be closer to 2,700.

Despite the amount of hardware out there, it seems that the opportunities for MRO (maintenance, repair and operations) providers have barely begun. Most wind farms are less than a decade old – just seven of the wind farms on the CanWEA list predate the year 2000 – and many machines are just starting to come out of their original equipment manufacturer (OEM) maintenance service warranties.

“In Canada, manufacturers have a strong hold on warranty service. We do not have any service technicians working for us currently. I work directly with our OEM,” explains Trevor Smith, maintenance supervisor of a large Ontario wind farm (he requested that we withhold the farm’s name). “The WTG maintenance industry is in its infancy,” he emphasized.


“It is really hard to find a Canadian company to come in and competently work on wind turbines,” says Smith. “One problem I see with the industry now is the lack of local repair loops. With large pieces of equipment, there are a lot of components and not a lot of local repair loops. We are trying to get manufacturers to outsource equipment, such as gearboxes, to more local companies.”

Almost all of the big turbine equipment suppliers, such as Enercon and Vestas, have two- to 10-year warranty maintenance service contracts, or longer, according to Jason Van Geel, president and general manager of Carlsun Energy Solutions, headquartered in Port Elgin, ON. “Every project starts this way.”

Carlsun, along with Cambridge, ON-based Moventas Ltd., are notable exceptions to this OEM lock on MRO work. Moventas, one of the world’s largest manufacturers of wind turbine gears, does gearbox inspection, repairs and rebuilds for Canadian WTG owner-operators. Carlsun, founded in 2005, divides its expertise roughly equally between working as a general contractor for WTG installations and being the provider of non-construction services.

“We are among the very few companies in Canada approved by equipment suppliers to work on their WTGs,” says Van Geel. That said, the company’s expertise is the replacement of major components, not MRO, at least as of yet.

So far, there are a few other small-to-medium Canadian companies equivalent to non-OEM type MRO providers, such as United States-based Energy Maintenance Service LLC of Gary, SD, or Outland Energy Services of Canby, MN. There are none of the size of, for example, the massive non-OEM independent company, EnXco, based in San Diego, CA, according to Mark Eagle, wind gear and field service manager, Moventas. (EnXco has a Canadian affiliate, EDF EN Canada, based in Toronto.)


Maintenance and servicing


The main equipment in a WTG, for example, the gearbox, generator, pitch and yaw motors and hydraulic systems, are contained in the nacelle – a boxy structure to which the blades are attached – that is perched on top of the tower. For scheduled inspections and lubrication, which take about two days for each turbine, the WTGs must be shut down.

Maintenance schedules are manufacturer-specific. Some recommend a six-month service schedule for some components, such as filters and for lubrication, with more extensive inspections on a 12-month schedule. The chance of an unscheduled, forced visit for maintenance within any six-month period is about 30%, according to Smith.

Scheduled servicing is mainly lubrication: grease, oil, hydraulic fluids for yaw and pitch systems, and for drive trains. “There are moving parts everywhere. They need lubrication and maintenance,” Van Geel explains.

“When servicing gearboxes, Moventas’ techniques include endoscope inspections and vibration analysis, done every couple of years.

WTGs are special workplaces. Technicians must climb 80 metres or so up the inside of the towers to reach the nacelles. Tools for up-tower repairs are selected for their size and weight. Technicians must carefully plan for each repair to avoid excessive downtime.

Space inside the nacelle is limited and major components are extremely heavy: a 1.65 MW generator, for example, weighs 55 tonnes. Gearboxes weigh up to 30 tonnes. For the record, blades weigh roughly 7,500 kg apiece and might be 49 m long. A nacelle and the hardware it contains typically weighs between 81,600 kg and 82,600 kg and an entire WTG can weigh over 317,500 kg.

A minor overhaul would involve a generator alignment or lubrication pump replacement. Some equipment can be disassembled and lowered from the nacelle with a built-in service crane. “Newer and larger turbines tend to be more serviceable,” says Moventas’ Eagle.

A gearbox replacement would be a major exercise. A specialist company like Carlsun might bring in a 650-tonne hydraulic crane to remove a gearbox and replace it with a spare. Moventas, on the other hand, would remove and repair or overhaul the faulty gearbox in its own shop.

Eagle describes some of the main challenges working on WTGs. “Besides the obvious problems associated with working 90 metres up in the air, the space up-tower is very limited. Moving around the equipment is difficult and takes a toll on the body and sometimes even one’s patience. Good housekeeping is a must and goes a long way to reduce fatigue and speed up the job. When the winds are high, it’s too dangerous to perform some procedures.”

Workplace safety quickly comes out in conversation. “There are very stringent safety qualifications. Safety is tied with technical qualifications in greatest importance and is a very significant department in our company,” says Van Geel. Safety training includes learning how to execute high-angle emergency descents by rappelling from the nacelle.


On-line monitoring


Nacelles may only be visited with a buddy and there are stringent safety protocols. Daily inspections are, therefore, impractical. Manufacturers offer at least basic on-line monitoring, generically referred to as SCADA (supervisory control and data acquisition). The OEM SCADA at the wind farm where Smith works does not include vibration analysis of major components, except to prevent abnormal operation of equipment, such as blade over-speed or tower oscillation. “The monitoring system is designed to keep the machine within normal operating parameters,” Smith explains.

More sophisticated condition monitoring systems, however, are slowly gaining acceptance on Canadian wind farms. Moventas offers its Condition Management System (CmaS), which monitors, stores and analyzes data for seven key parameters: temperature, vibration, load, pressure, RPM, oil ageing and oil particle content. The company recently won a contract with GDF Suez (a Belgo-French energy company with North American headquarters in Houston, TX) to install CMaS in 100 Canadian WTGs.

SKF Canada, which already has on-line monitoring systems in more than 1,000 WTGs worldwide, is working to crack the Canadian market. Its WindCon product detects failure modes for equipment on variables such as alignment defects, shaft deflection, clutch and bearing defects, and gear damage and wear. It is currently running a single pilot project, but SKF is ready for much more action: Its remote diagnostics centre in its new Solution Factory in Edmonton is equipped for remote data capture, analysis and diagnostics reporting.

Despite the acceptance of on-line monitoring systems in other industries, Canadian wi
nd farm operators appear not to have wholeheartedly embraced them yet. “In the wind industry, the top priority is to build new capacity. Remote monitoring and predictive maintenance strategies are still being developed, since significant [numbers of WTGs] are still under warranty or just after the end [of them],” says Hugues Martel, division manager, Reliability Systems, SKF Canada. “[But] the earlier that some preventive and corrective maintenance tasks can be scheduled, the more you can save money. For example, some bearings can be changed in the nacelle if you detect the problem early enough. The business case for condition monitoring on wind farms is driving down the cost of doing maintenance.”


Multiple skills needed


Historically, according to Smith, who is is an aircraft mechanic by training, WTG technicians have come from diverse backgrounds. “When I first started, I met linemen, electricians, millwrights, mechanics … one was a farmer with phenomenal skills. The focus was on the breadth of their experience, their ability to excel, their attitude and their personalities … getting along at the top of the towers. Personality is really big.”

A WTG technician has multiple specializations in, for example, mechanics, electrical systems, electronics and hydraulics, Smith explains. “You cannot have someone who is just an electrician. They need a broad understanding of systems.”

Possibly the best-equipped place in the world to receive training on wind turbine systems, if Greg Peterson is right, is in Lethbridge, AB. He is the program administrator for the International Wind Energy Academy, and the industrial and technical training department, at Lethbridge College.

The Lethbridge College International Wind Energy Academy has been offering a 32-week wind turbine technician program since 2004 and has graduated about 150 technicians to date. “It is probably the most comprehensive training program that we have seen,” Peterson says. “The key to it is the extensive scope of equipment that we train students on. Our equipment includes 250-kW to 1.8-MW generators and gearboxes, training units for hydraulic systems and sensors, a training tower, a nacelle safety simulator and blades.”

Students come from as far away as South Korea, China and Australia to take the program and graduates can go directly to work in the wind turbine maintenance industry, Peterson says. “The program is 100% driven by service companies [OEMs]. An advisory committee, which includes wind industry OEMs, reviews and makes recommendations on the curriculum.” OEMs will put graduates through additional specific training on their own systems and equipment.

The future for technicians and non-OEM service companies would seem bright. As of last August, according to CanWEA, there were 72 new projects, with a total capacity of 8,695.2 MW, that had signed purchase power agreements and/or that were under construction.

That means there will be roughly another 5,800 WTGs that will need servicing, and the counter keeps on spinning. For example, Alberta alone has an estimated 11,500 MW of proposed wind applications, and environment ministers across the country are plugging wind power as their clean-energy salvation. MRO


Montreal-based Carroll McCormick, an award-winning writer, is the senior contributing editor for Machinery & Equipment MRO.


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