WIND ENERGY EDUARDO VICENTE G.T.RIVI – LINCOLN SPAIN How to reduce wearing on gears while pitching from 0-degree From the beginning of the wind energy industry, 30 years ago, wind turbine models have grown up to high energy power per each wind turbine. This power installed per wind turbine leads to the needing to optimize the maintenance and to increase the reliability; a new technical challenge for wind turbine designers. A lack of lubrication can bring WTGs to a standstill. The increased cost of lubricants and maintenance duties, coupled with a higher equipment value, drives the need for automatic and centralized lubrication systems. H arsh conditions such as vibration, mechanical loads, contamination and moisture cumulatively result in a high wear rate for gears and friction points. Proper Lubrication is absolutely necessary in order to provide the right protection. A poor preventive maintenance in a wind turbine might lead to continued nondesired breakdowns and to apply corrective maintenance. Predictive & preventive maintenance are being optimized in order to maximize energy generation. For this reason new multimegawatt WTGs house autonomous systems that contribute to decrease the maintenance tasks. By using Automatic Lubrication Systems, the lubricant is automatically delivered in time-controlled and metered quantities to all connected points in the system, while the WTG is in operation. Lubrication “in motion” ensures that the lubricant is optimally and evenly distributed within the bearings. But it actually does not happen in Pitch Gears systems, due to here only a 90-degree cog segment is actually used. Automatic Lubrication becomes more difficult by the fact that for around 90% of the production time of a wind turbine the rotor blades remain in what is known as the 0-degree setting and is adjusted by only minimal values. Two to three teeth of the open gear drive are therefore exposed to extremely high loads for 90% of the time that the turbine is in production. 40 Excessive wearing on gear tooth flange Conventional lubrication of this cog segment can therefore only be achieved if the rotor blades pass through the complete 90º segment during a maintenance session. However, as maintenance normally cannot be carried out without taking the turbine offline there are only two options for lubricating the rotor blade adjustment gear: • Lubrication during the natural idle phases (no wind) • Compulsory maintenance intervals, associated with additional loss of production The idea of adapting the lubrication task to natural idle phases is attractive to wind farm operators but not at all to designers or maintenance staff. The fact is that production phases may be extremely long during extended periods of windy conditions. These periods tend to be longer for offshore plants than for onshore installations. In such cases there is a possibility that the lubricating film will degenerate and fail before the end of the natural wind production phase, thus causing damage to the gear drive. For gear drive lubrication there are essentially two acceptable methods that can be applied to wind turbines: • Spray lubrication with compressed air, which due to lack of pneumatics in WTGs makes it unfeasible. • Mechanical pinion gear lubrication, which is the most used. Regardless of the lubrication method that be used, it is important that the proper type of lubricant be applied in the required amount, at the right time, and on the right tooth. Right lubrication on gears not only reduce wearing, but it also eliminates risk of pitting, micropitting, scuffing, bending fatigue, and other mechanical failures inherent to high loads on open gears. It is also important to take into account that protection to corrosion is becoming critical issue; due to Wind Turbine market tends new developments for offshore environment and cold climate conditions, where C4H or C5M comes to be mandatory. MicroLubGear (MLG) is a novel technology to avoid the energy generation loses to lubricate the pitch at 0º position. Microlubgear – combined with a right Automatic Lubrication System – lubricates the tooth in contact while the wind turbine operates and pitch system is working. It’s just so simple. It’s just so accurate. It’s just so efficient. energetica international · Nº 4 · MAR14