Special Report

How to get optimal performance of wind turbines

Analysing how to get optimal performance of wind turbine.

In the recent years, renewable energy has become an important industry. India has seen the installation of nearly 28 GW of Wind Turbines Generators (WTGs) in the last financial year which affirms the commercial viability of the wind farms. Wind is the raw material and is available for free. But it varies in strength and direction throughout the year depending on location and season. In India, the year is divided into the high wind season (April-September) and the low wind season (October-March). Wind generators reap the greatest benefit if their machines are operational during the entire high wind season.

Sharing his views on how to get optimal performance of wind turbine Rajeev Sharma, Vice President O&M, Asset Management, Mytrah Energy (India) Ltd states, “With over 1 GW of installed wind power capacity, Mytrah Energy obviously has a strong focus on maintaining the operational efficiency of its entire wind portfolio.” He also shares few points on the same:

Machine availability in the high wind season: Machine availability is an industry term for the percentage of time for which WTGs are in the running condition. O&M players promise more than 95 per cent machine availability. Power producers have a strong commercial incentive to ensure maximum availability is during the high wind season.

Regular monitoring of the power curve: Every WTG manufacturer shares a guaranteed power curve with producers. The WTGs generate varying levels of power depending on the wind speed, air density etc. The power curve for each machine is generated regularly and monitored for any deviation. If a deviation is observed, the turbine is placed under observation for further action.

Planned and scheduled maintenance: At the end of the high wind season, the entire machine is inspected for its health. The maintenance is planned only during the low wind season when the wind availability, and consequently power and revenue generation, is very low. Regular maintenance of WTGs is essential to maintaining their health. With planned maintenance activities, emergency shutdowns are reduced and efficiency is improved.

Turbine health check-up: Two years post commissioning, a comprehensive health check-up of WTGs is performed to help asset owners identify issues and ensure completion of warranty obligations from the supplier. A check-up involves the physical inspection of every component of the WTG, including the endoscopic inspection of gear box internals and blade internals, inspection of the outer surfaces of blades and tower with drones, thermal imaging of hotspots in the electrical panels and cables etc.

Forecasting and data analysis on a real-time basis: Wind forecasting studies help estimate the power that can be supplied by a wind farm, to the grid. This helps develop revenue projections and, more importantly, helps protect the grid from over and under-generation.

Wind turbines operate under extreme conditions, such as extremely low or high temperatures as well as corrosive environments. It is important to protect the wind turbine gearbox to ensure smooth functioning and ensure equipment protection for optimal performance of the wind turbine. Shankar Karnik, General Manager-Industrial, ExxonMobil Lubricants Pvt Ltd briefs, “When it comes to wind turbine equipment and optimal performance, the first, and most important consideration should be lubricant formulation. If you select the right lubricants, you will be better protected in the long run and you won’t need to worry about the life of the equipment or much downtime.”

ExxonMobil designs gear oils and greases to ensure adequate and optimised performance of wind turbines, while preserving the life of the gear box and other critical components, extend oil drain intervals and reduce overall maintenance costs. This provides optimum equipment protection to wind turbine gear boxes ensuring long lubricant life even under extreme conditions. ExxonMobil recommends the use of synthetic grease which protects wind turbine bearings from extreme temperature conditions ranging as high as 120C to as low as 50C. These are a superior performance lubricant especially suited to exceed the demanding requirements of wind turbine applications at extreme temperatures.

ExxonMobil’s wide portfolio of grease, gear oil and hydraulic oils are designed specifically to meet the challenges of equipment in extreme conditions of temperature, load and water contamination. ExxonMobil’s products help to sustain maximum power output from wind turbines by attaining optimal performance.

They minimise unscheduled and costly downtime for maintenance and repairs, helps to extend oil drain intervals as well help to preserve the life of the equipment/components.
Mobil SHC Gear 320 WT is gear oil designed to provide protection from wear and corrosion, anti-foaming. The oil provides excellent water tolerance which helps prevent lubrication failure due to emulsion formation or oil breakdown under wet condition and provides minimal unscheduled downtime and maintenance, which leads to longer gear, bearing and oil life.

  • Mobil SHC Grease 460 WT and Mobilith SHC 100 are grease designed for main, pitch, and yaw and generator bearings.
  • Mobil SHC 600 series is oil designed for ancillary gear boxes. It promotes operational reliability and energy efficiency, longer oil life and has high and low temperature capability.

T F Jayasurya, Country Manager-India, Windsim says, “The wind speed is the single most important factor for establishing profitable wind farms, due to its extreme power output sensitivity and large variability, good due-diligence, micro-siting, using advance wind farm assessment tools, analytics of measurement data looking into IEC constraints, optimised farm design for maximising Annual Energy Production (AEP) for a viable project.”

SKF has been working with leading OEMs to optimise turbine performance, reliability and energy output since the industry began. “Today, we’re helping wind farm owners, operators and maintenance providers do the same with a range of wind maintenance solutions that can help drive uptime, add value and increase performance at every turbine life cycle stage, states Abhijit Kulkarni, Head of Energy Sales, SKF India.

He adds, “Backed by our extensive global engineering, manufacturing and service footprint, we can provide our customers with original or upgraded products with quick deliveries, anywhere in the world. SKF can help to predict the remaining service life of components with vibration measurement and analysis via remote monitoring, enabling greater machine uptime and much more cost-effective planned maintenance.”

Together, SKF’s Life Cycle Management solutions help its customers optimise turbine power output and improve the life cycle of the equipment.

Few of SKF’s turbine optimisation solutions are:

  • SKF’s widest range of products for wind industry takes care of almost all requirements of wind industry. Its high-capacity cylindrical roller bearings, separable cylindrical roller bearings, XL hybrid bearings with ceramic balls, SKF INSOCOAT bearings and black oxide-coated bearings comes with improved performance and lifespan.
  • WindCon for early detection of mechanical problem reduces down the chances of downtime and prevents failures to a large extent.
  • It’s newly launched remote diagnostic services for wind farm remote monitoring is a great support and has been helping its customers in reducing downtimes.

Briefing on how to get optimal performance of wind turbine Dr. Anil Gupta, Director, Enerfra Services (India) Pvt Ltd says, “Turbine maintenance is an important area. Rather than just focus on uptime of the turbine, for profitability, one has to take a broader look to improve output as well. In addition to maintenance, three areas are key to optimal returns. Firstly, good analytics on wind turbine data to understand differences between turbines, wind farms, and optimisation of the entire wind farm. Secondly, maintenance of EPC including right of way lines, tree trimming, and health of insulators, and lastly maintenance of blades, especially erosion of leading edge. In addition, performance for certain turbines can be increased up to 3 per cent in slower winds via vortex technology.”

How maintenance can achieve wind farm profitability?
The most economical application of wind turbines is in groups of large machines. They are called ‘wind farms’ or’ wind power plants’. Wind plants can vary in size from a few mega watts to hundreds of mega watts in capacity.

Real-time monitoring of operations: At Mytrah Energy, a proprietary application called Generation Monitoring Centre (GMC) is used to monitor all wind assets real-time from a remote location. The GMC team flags off any machine issues in real time to site-based maintenance teams so that they can address them immediately.

Analysis of frequently occurring faults: The maintenance team analyses the frequently occurring faults in each wind farm. This activity helps in planning the availability of tools and spares thereby reducing cycle time. Major faults, if any, are addressed in the planned maintenance before every high wind season.

Monitoring of sub-station: The sub-station is an integral part of any wind farm. Power generated by the turbines is pooled at the sub-station and then transferred to the grid. Obviously, therefore, the performance of the sub-station is as important as that of the turbine and the grid. The sub-stations are monitored closely year-round while planned maintenance activities are carried out during the low wind season.

Explaining the role of maintenance in achieving wind farm profitability Sharma says, “Wind farm owners looking to improve the generation of their wind assets can avail of the remote monitoring, performance monitoring and turbine health check-up services offered by Mytrah. These services can have a significant impact on turbine performance and, consequently, on the revenue generation potential of their farms.”

Wind farm operators are constantly challenged to produce more with less: less capital investment, fewer people, reduced maintenance budgets and many more. “SKF can help optimise the efficiency of the wind turbine and implement technologies to reduce maintenance costs. This will strengthen the profitability of wind farms and will generate higher benefits for the operators,” informs Kulkarni.

SKF’s products, lubrication systems, remote diagnostic services and technical support ensure a winning partnership with its customers. The operators can achieve:

  • Fewer site visits and unplanned stops.
  • Cost-effective, pre-planning of maintenance, bringing in cranes, service crews and replacement parts well in advance.

Maintenance is the key for any equipment to deliver the expected and sustain the design performance levels, believes Jayasurya. He says, “A professionally managed Operation & Maintenance (O&M) with developments in O&M management tools and advanced maintenance strategy, the downtimes of the wind turbine are minimised and also severe damages to the critical component in the wind turbine are reduced. Beyond all the above efforts, the advancements in utilising available data and digital analytics help in improving the efficiency/AEP to next level.”
Wind energy brings low component running cost, which makes it an optimal source of energy in the long run, believes Karnik. He says, “But when it comes to wind energy generation, wind turbine lubricants need to last long and offer excellent oxidation and shear stability, all the while protecting key turbine components such as gears from micropitting and main bearings from failure etc. As wind energy is free, running costs are considered to be low. The only ongoing cost associated with wind energy is for the maintenance of wind turbines. To successfully run operations today it would require not only efficiency and productivity, but also ensure safety by reducing risks in human to machine interface as well as control and reduce environmental impact. It is therefore essential to minimise unscheduled downtime and maintenance, extend gear and bearing life under high-stress operating conditions. Reduction in maintenance and unscheduled downtime helps to mitigate potential employee risks arising from direct contact with equipment, reduce carbon footprint, achieve operational goals and enhance competitiveness by increasing efficiency, reliability and productivity.”

ExxonMobil’s specially designed synthetic oils and greases provide excellent protection against wear and tear, rust and corrosion adding to improved performance, longevity of equipment as well as wind turbine productivity. They help to cost-effectively maximise wind turbine productivity by improving equipment performance and reducing the need for maintenance.

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