Introduction
The call for sustainable energy is increasing each year and the wind turbine industry keeps on growing. Only in 2020 the U.S. capacity grew from 105 GW to 122 GW. By each year, models increase in size, sophistication, and capacity. But, whether new or older, all models carry weaknesses.
According to research in wind turbine maintenance, gearboxes present the second leading source of wind turbine failures (amounting to 12% of all failures, with the control system presenting 13% of all failures). One would expect this trend of malfunctioning gearboxes to decrease as the industry evolves, but it surprisingly keeps growing annually. The main culprit for gearbox failure is the lack of lubrication (Yateks, IJPE).
Gearboxes: The main component at risk
Gearboxes are essential components and hold many purposes. The main gearbox’s task is to speed up the slow high-torque rotation for the generator – a strenuous contribution which leaves few machines in good working conditions for over ten years. Another important gearbox is the yaw-drive which, sometimes with strong resistance, adjusts the turbine’s direction to an optimal position where it can harness the most power while avoiding structural damage.
The issue primarily lies in the unreliable environmental conditions in which the machines operate, periodically putting heavy pressure on the machinery. Many wind turbine models are constructed to handle extremely high loads on the bearings in conjunction with high wind speeds, with the winds helping to balance the load and strain on the machinery. The weaker the wind, the higher pressure on the bearings.
The remedy for the aches of the low wind pressure is a high dose of lubrication oils. When the rotation slows down, the heavy loads result in a breakdown of the lubricating oil film. The main culprits identified in the lubrication drama are; substandard systems, casual maintenance, and oil leakage. Other factors putting the main gearbox at risk are vibration, temperature, and moisture (Machinery Lubrication).
“To date, we have seen very poor maintenance procedures in the field. These will have to change dramatically, especially for the larger sizes of wind turbines and gearboxes where exposure to higher oxidative and wear stresses will occur quickly.” - Jo Ameye, global sales and marketing manager of Fluitec International
The importance of available lubrication oil
When the gearbox is not adequately lubricated, damages occur from conditions such as micropitting and scuffing. If consistent, cracks can start to form on the gears and create a chain reaction of events. In worst case, this usually equals a system breakdown and gear replacement. The gearbox oil is effectively lubricating the gears to reduce friction that would otherwise cause damage. As a plus, it also maintains a clean environment from contamination while protecting the metal gears from corrosion.
If oil unfortunately does leak, the countdown begins until the mechanics start to take damage. A common culprit in wind turbine oil leakage is unfavorable oil pressure, which can even present a risk of pipe rupture. Other common reasons are deteriorated seal ring, incorrect pipe joint installations, blocked pipeline/oil filter, and excessive oil viscosity (which increases leak probability) (IJPE).
Costs of disruptions
“The cost of gearbox maintenance and replacement — including the cost of turbine downtime for O&M and repairs — is a significant part of a wind farm’s operating losses. The condition of gearbox oil in the wind turbine is one critical factor in saving on these costs”. - Windpower Engineering
As the quote shows, the failure of a single component can too easily spiral into a muddle of costly developments.
A scenario of gearbox failure
As wind conditions vary, wind turbines generally perform between 35-65% of the time, producing between 1-5 MW/hour (depending on size and technology). According to statistics, a 4-megawatt turbine at 35% capacity harnessed energy worth $245,280 – 50% capacity resulted in $350,400, and 65% at $455,520 (Anemoi).
Assuming 50% capacity of a 4-megawatt turbine, equaling $350,400 in annual earings, three weeks of downtime would equal $20,160 in passive losses alone.
We also have the gearbox, which constitutes about 15% of the total wind turbine cost, and a 2-megawatt wind turbine costs $2-4 million. Counting on the low end by $3 million for a 4-megawatt turbine, the main gearbox in itself would amount to $450,000 of the total bill. A costly part to replace.
Although far less costly, a less amusing expense is of course also paying personnel for a project that could have been avoided. With a U.S. wind turbine technician’s well deserved median annual salary being $56,230, it is gonna cost a little bit.
In the end though, time consumption might be the greatest irritant. Detecting the faults then ordering and installing new mechanics can result in weeks of downtime.
More costs are likely to be added when a system malfunction occurs, such as for replacing oil filters or broken pipes. Here, we do a simple calculation of a scenario where oil leakage has resulted in gearbox failure.
$20,160 in losses due to three weeks downtime
$450,000 for gearbox replacement
$2,520 for three technician’s three full working days (all trips included)
Total costs: $472,680
Ok, so you get it, it is expensive. Let us now brighten it up with solutions that can easily prevent a wind turbine breakdown from those scary oil leakages. With proper monitoring and maintenance, such issues should never reach that far.
Smart wind turbine maintenance
With the usually remote placement of the wind turbines, regular inspections are neither practical nor financially viable. Unfortunately, oil leakages do occur frequently and they can rapidly put the machinery at risk. The helping hand here, bridging between need and costs, is remote monitoring.
Sensative’s Strips +Oil steps in to fill a void in the wind turbine maintenance industry, offering the ability to easily avoid unnecessary costs, damages, and pain by remote IoT monitoring.
The solution is quite simple: The ultra-slim (3mm) sensor can be mounted on any area where oil is likely to leak due to turbine equipment malfunctions. This can be when a pipe bursts due to excessive oil pressure or when a seal ring has been worn out.
Due to its properties, oil travels down via surfaces rather than dripping and this makes it easy to “catch” the oil leak as it occurs. Simply place the sensors strategically inside or outside the nacelle and receive alarms via the LoRaWAN protocol to your platform when the sensor detects oil (soaks up oil).
“The main factor affecting the failure of the gearbox is the lubrication problem. So, oil monitoring and fault diagnosis of wind turbines are effective means. It can improve the reliability of wind turbines.” - Yateks
As our Strips +Oil sensor can detect both water and oil, both liquids can be monitored for. This could be in a location in the wind turbine where leaking oil can appear and condensation accumulate. In addition, Strips +Oil also includes a temperature sensor that can monitor the indoor temperature of the nacelle or the outdoor conditions at the wind farm.
LoRaWAN for long-range monitoring
The LoRaWAN protocol, an abbreviation of Low-Power Wide-Area Network, is highly suitable for these remote applications as it allows frequent updates to be sent over vast distances (30km+). The low power consumption equates many years of service for wireless devices before the battery or sensor needs to be replace. When using our Strips +Oil for LoRaWAN, you can expect up to 10 years or more of operating life without the need for any maintenance. In other words, you can simply install the sensor and then let it do its work for years ahead.
A capable IoT platform for a strong foundation
An IoT platform, such as Sensative’s Yggio DiMS platform, is then used to collect data in real-time, visualize trends, set up scenarios, and receive alarms. Our experience with commercial and public actors alike have resulted in customers having unusual freedom in designing their experiences and setups while relying on high security standards.
In addition, the Yggio platform is built on open technology, allowing an impressive range of hardware and software from separate manufacturers to be combined. There is no limit to how you expand your IoT operations once you start. Due to its versatility, the platform can act as a host of layers such as the service, processing, or device layer, allowing you to combine software as you wish.
Shop for Products
The Strips +Oil sensor can be found and ordered via our webshop. For larger quantities or if you want to discuss your needs, please contact us and we will guide you through the process.
If you are interested in employing Yggio, want to see a demo, or need help tailoring a solution for your specific needs, contact our sales team to evaluate your possibilities and requirements.
