In the wind industry, it is well-known that a downed tower results in major financial losses. The question arises: how can turbines get up and running as quickly as possible for as long as possible? When system components fail due to hydraulic rams, yaw drives, and accumulators, for example, choices then become very limited. You are then left with the decision to purchase new units or obtain refurbished or repaired units. Two major pitfalls of buying new units are long lead times that are encountered and the logistical challenges of receiving new units that are manufactured nowhere near wind farms. For instance, wind farms in the U.S. that have turbines manufactured overseas are forced to absorb the cost of obtaining new components from the manufacturers. The high costs of shipping and long wait times have caused wind farms to start looking for regional solutions closer to home. These factors have paved the way for the repair industry. By purchasing refurbished units, the logistical challenges associated with buying new units are eliminated. However, the quality of repair is then called into question. When buying new becomes unfeasible or too expensive, what is the best course of action when deciding which route to take with repaired units?
Quick Fix or Quality Fix?
Due to the difficulties and costs associated with buying new units, companies that are refurbishing units have found a niche in the wind industry. There is a demand from wind farms with downed turbines to seek out this route because of the economic advantages of decreasing the costs related to shipping and long lead times. Repaired units have received a mixed reputation due to the sources of repair. Something important for customers to consider when looking at refurbished units is the fine line between the quick fix and the quality fix. There are benefits and drawbacks to consider when looking at each. Up-tower repair companies have stepped into the role of the quick fix. Independent, regional repair facilities, such as Lighthouse Global Energy (LGE), have opted for the quality fix. The greatest benefit of up-tower repair is how quickly it’s completed.
This is the quickest way to get the turbine running again, but will the repair last? From the perspective of LGE, the long-lasting repair is more important than the short-term fix, even if the turnaround time takes slightly longer,. LGE has taken the time to do the little things right, and it is this attention to detail that leads to long-lasting, high-quality repairs. Furthermore, LGE is strategically located in Abilene, Texas, where wind energy plays a predominant role in the region. A dedicated repair facility is able to focus in and provide areas solely devoted to a particular job, which in turn, allows for specialized fixtures and tools to be fabricated that make the job easier and more efficient, as shown in Figure 1.
This increases workplace safety and allows for consistent practices to be implemented that reduce the risk of damaging components. LGE has extensive knowledge in quality procedures related to ISO 9001. This enables the technicians at LGE to leverage the quality associated with ISO 9001 and address repairs quickly. However, without knowledgeable technicians, quality and speed are pursued in vain. In comparison of the two repair styles, up-tower repairs are primarily focused with speed, and independent facility repairs are primarily focused on quality. This doesn’t mean that one can’t produce quality and the other can’t produce quickly; it just demonstrates each type’s specialty.
The Dirt on Buying Used
Contamination proves to be the leading cause of problems with many turbine components, especially in hydraulic systems. Hydraulic cylinders (or pitch rams) serve as a good example to consider when looking at the two repair philosophies. How does an independent repair company such as LGE approach the solution when compared to an up-tower solution? When a cylinder goes down, contamination is attributed as the primary mode of failure in hydraulic systems due to the effects of dirty oil [1]. Dirty hydraulic fluid not only damages cylinders, it can also damage other major components, such as pumps and valves, as shown in Figure 2.
Turbine hydraulic systems are not exempt from this plague, especially in the windswept plains and farmlands of West Texas. When looking at the repair of a hydraulic cylinder, it is essential to be as clean as possible in order to protect components from dirt and other foreign particles that can wreak havoc on rods, seals, and barrels. This becomes problematic for the up-tower solution. If systems are failing due to contamination up-tower, then an up-tower repair will be done in a contaminated environment. This results in repairs that don’t last long, and wind farms quickly fall back to the same predicament as before. Whereas an independent facility devoted to these types of repairs is able to provide a sterilized environment and practice better cleaning techniques to carry out an effective, long-lasting repair. One improvement LGE has utilized recently is through the use of bellows made of a tougher material with a zip-up design for easier installment in order to protect rods more effectively in dirty environments, as shown in Figure 3.
This allows for the problem to be combated before it occurs. Contamination is important to consider not only in hydraulic systems, but also in gear drives and where oil and moving parts are implemented.
Testing the Repair
Testing refurbished units to conditions experienced in the field is a proven way to know if repairs are good or bad. Whether it is a leak check in a hydraulic system or a torque test in a yaw drive, the information gathered from testing is essential to developing the best repair solution. It is through this process of testing and R&D that the best repair solutions are developed.
“The reason we have been able to get the customer base we have is because of our high-quality testing procedures and our ability to accommodate customer delivery schedules,” said Ruben Guerrero, LGE’s business development manager.
LGE has devoted a lot of time and money into engineering and research for making the best possible tests to simulate the complex conditions experienced in the turbines.
Whether it is looking at the surge in forces components experienced during a windstorm or using computer software to analyze the effects of forces on various components, these factors come into play when developing good tests. This type of attention to detail ensures that long-lasting results will be provided for customers who want turbines to work effectively for as long as possible. If repairs are being done up-tower, the only way to test the unit is to install it. The result of a failed test means that the turbine is again rendered idle. Operating with one bad component in a system puts unnecessary strain on other components that depend on each other, possibly causing a domino failure effect, particularly in the pitch system where a bad pitch ram can lead to pump or motor failure. This is where getting it right the first time becomes especially important, and pre-tested repairs are able to provide the best chance of doing just that.
Conclusion
There is a demand for refurbished and repaired turbine components because of the economic and logistical challenges of buying new. The two main avenues of repair that have emerged are up-tower and dedicated regional repair facilities. These two avenues of repair are able to address the ever-growing need to reduce the cost and minimize the need to transport units over long distances. The main benefit of the up-tower repair is the speed and immediate locality of the repair. The drawbacks are the loss of quality with working in a contaminated area and the inability to carry out effective tests up-tower. A dedicated repair facility can produce higher quality products that last longer in the field, but it will more than likely take a little longer for the turnaround. The ability to mitigate contamination and test products before installment prove to be big players for quality in the repair arena.
For more information, go to www.lgnrg.com.
Reference
1. http://www.plasticstoday.com/articles/primary-cause-hydraulic-system-failure-dirty-oil
