Akhil Jha, Vice President Technical, Shell Lubricants India discusses technologies that OEMs can adopt for wind O&M.
Operations and Maintenance (O&M) as an industrial function comprises of a broad spectrum of activities required to assure that the set-up, equipment and parts of a factory/unit perform the functions for which the facility was constructed. There are multiple benefits that timely maintenance practices bring to the table - these ensure maximum utilisation of capital investment; minimised factory down time; increased efficiency and profits, as well as the safety of employees handling heavy machinery.
India´s power sector is one of the most diversified in the world. Also, electricity demand in the country has increased rapidly and is expected to rise further in the years to come. To meet the increasing demand for electricity in the country, massive addition to the installed generating capacity is required.
Lubricant technology plays a vital role in keeping wind turbines running reliably and efficiently. OEMs and customers today are constantly striving to improve efficiency and operational reliability, and enhance competitiveness by avoiding loss of output and increased maintenance costs.
Besides reducing friction and offering strong reliability to equipment, lubricants also play a vital role in terms of energy efficiency. For power generation industries or plants, reliability and uptime are considered extremely important factors for both traditional and renewable forms of energy, including gas turbines, nuclear turbines, wind turbines or HFO fuel-based engines.
Poor lubricants and lubrication practices can cause equipment downtime which can lead a firm to losses. In today´s operations, lubricants become a critical element in the life-span of a turbine where severe conditions and cyclic peak loading are the new norm.
The wind industry has traditionally believed that value creation is concentrated in manufacturing and wind farm development. One of the most important aspects of a wind turbine is the reliability of its ´critical´ components (gearbox, generator, blades etc.). These parts need to be properly conserved and maintained to achieve an optimum level of performance and reduced need for costly maintenance.
Typically, in wind turbines, large components´ failures take 8-10 weeks or longer to repair/replace. Especially in today´s scenario of high demand, component lead time represents more than 80 to 90 per cent of total downtime.
Small failures are frequently the most common cause of unavailability. The following are some of the challenges faced by wind industry and suitable O&M trends need to be adopted accordingly.
1. Remoteness of wind turbines and harsh conditions both on and off-shore; difficulty with maintenance - reliance to on-board sensor technology; low temperature start-up procedures and need for excellent low temperature; fluidity; potential for accelerated corrosion/rusting, especially in off-shore application; increased interest in lubricant design in relation to white etching failures.
2. Design of wind turbine gearboxes: compact design creates additional lubrication challenges - air entrainment; surface finish and manufacture of gears critical for long term service life; demands for lubrication of bearings and tighter product cleanliness targets - move to finer filtration.
3. Expectation for longer oil service life: synthetic gear oils offer benefits in reduced frequency and cost of oil change outs; provide protection for bearings and gears over service life; better life of filters and breathers.
One can describe maintenance practices on wind turbines as either ´preventive´ actions performed at routine intervals as per the manufacturer´s specification, or ´reactive´ when a turbine´s component is damaged causing the machine to shut down.
Today, new ´preventive´ maintenance practices are being developed, using high-tech condition monitoring technologies, which aim to reduce the overall turbine O&M lifetime costs.
Wind OEMs are now focussing more on predictive maintenance techniques which have arisen to maintain, visually inspect, measure, and analyse the condition of the turbines and perform required repairs through technology called Condition Monitoring (CMS). This technology, which is expensive at first, is said to lower the overall O&M costs of a turbine over its lifetime.
Wind turbine O&M practices are facing diversified challenges with respect to operating costs, asset management, reliability and component failures and right know-how on maintenance strategies.
Wind OEMs are increasingly getting familiar with component performance trends, seal compatibility issues, filtration challenges and basis of the new compliance of IEC 81400-4. OEMs are continuously focussing on design, reliability of their equipment and component performance through strong asset management diagnostic tools. The trends are more focussed towards operational issues, troubleshooting challenges and unscheduled maintenance planning, etc.
More trends are being followed to manage the optimising turbine power performance and on condition monitoring techniques.