Internship @ Gamesa Wind USA

I have just completed a two-week internship at Gamesa Wind USA, a wind turbine manufacturing plant. My father works there as a supply quality engineer and I have had the chance to learn concepts from many departmental staff, managers and my dad’s coworkers and I now have an understanding of the technical process of the machine as well as its components and their functions. Furthermore, I have been educated about the logistical, development and services, giving me a whole overview of the life of a turbine. I am sharing my newfound knowledge below.

A wind turbine is composed of a tower, a nacelle, a hub and the blades. The tower supports the electricity-generating components and ranges from 67m to 120m tall. The nacelle  contains parts that convert torque (rotational energy) into electricity for consumption. The hub houses three blades that produce the raw power. The blades are shaped like jet wings to improve aerodynamics. To the left is the Gamesa G8X, the current 2.0MW model.

Purchasing and Procurement

The first step towards constructing a turbine is purchasing and procurement. Each turbine costs around 2 million dollars. Gamesa primarily orders parts from manufacturers and assembles them on the production floor. This step is a complex and continuous operation that involves price negotiations, logistics, quantities, quality, appropriate emergency stock, shipping delays, ad nauseam. The objective of the purchasing and procurement departments is to never have to stop production due to lack of parts. In order to accomplish this, the purchasing employees find and negotiate with potential suppliers. Once they find a good deal, they must contact the supply quality department to homologate (qualify) the manufacturer’s products. This is a process that can take anywhere from a few days to a few months. Once the product is qualified, the procurement department can order and schedule shipping of the first batch.

Supply Quality

The quality department makes sure that the product that comes in from suppliers meets Gamesa’s requirements at all times during construction and operation. The PPAP Homologation is a six-step process that verifies that the product meets Gamesa and ISO requirements. Each time a part fails, an NCR (Non-conformity report) has to be filed. The quality staff attempts to troubleshoot the problem and find the root cause. It is the supplier’s responsibility to repair or replace faulty parts that do not match the blueprint or meet quality standards. However, the company is responsible for parts that fail due to human error during manufacturing. This procedure ensures the reliability of all parts of the turbine at all times.

Procurement

Sometimes, suppliers will be unable to meet deadlines, causing a potential shortage of material. The recommended inventory is 2-3 weeks of parts stored in the three warehouses available, and this can mitigate unforeseen delays. However, depending on the amount and importance of delayed parts, procurement may have to purchase from local suppliers or ferry by air. Both options are a great deal more expensive, considering that each major component can weigh several tons. Currently, Gamesa USA has over 100 suppliers all over the world and orders thousands of parts. It also obtains a considerable amount of inventory directly from Gamesa Spain, which has been around longer and benefits from more suppliers. This inevitably leads to mind-boggling amounts of paperwork, as employees balance inputs, outputs, plans and stock. Ideally, procurement would like 100% of supply to come from reliable local suppliers, thus improving communication and reducing shipping time. However, overseas suppliers are currently much cheaper, up to $10,000 less for every major component.

Manufacturing on the Production Floor 

The production floor continues the work by assembling the ordered parts into completed nacelles, hubs and tower sections. The production floor I visited only manufactures hubs and nacelles, but it was very impressive of its own. 

The Hub

The hub is composed of three blade bearings, three pitch cylinders, a frame and a cover. The blade bearings allow the blades to orient themselves towards the wind by spinning independently from the hub. Pitch cylinders drive this movement and adjust constantly. Two sensors at the back of the nacelle calculate wind speed and direction and control the spinning movement accordingly. Structural bolts hold the blade to the bearing and the bearing to the frame. Finally, a weather and corrosion-resistant nose covers the set.

The Nacelle

The nacelle contains the gearbox, the generator, the electrical cabinets, the transformer, the yaw gear, the main shaft, the hydraulic unit and the cooling system. It is a large rectangular box when finished. First, the main frame and the rear frame, two pieces of metal that constitute the base of the nacelle, are assembled. Then, the yaw ring and gear are set up in the frame. The yaw allows the nacelle to rotate on itself when it is driven by four gears, in a similar fashion as the blades.

On top, the main shaft, the gearbox and the hydraulic units are mounted. The main shaft is connected to the hub and rotates with the blades to produce mechanical energy. The gearbox is one of the most complex components of the turbine; its function is to accelerate the 12 rpms from the main shaft. The conversion factor of the current gearbox is 1:120. The decoupling device connects the gearbox to the generator and is partly constructed with composite materials to protect the gearbox and generator from too much torque. Once it is activated, the material burns and requires replacement. The hydraulic unit maintains pressure, lubricates the machines and powers the three brakes around the system as well as the cooling unit. It is filled with oil and works like the pistons inside a car, increasing and decreasing the amount of oil to control pressure. The gearbox and main shaft are padded with rubber composites to absorb shock and vibration.

Then, the generator, transformer, cabinets and cooling system are installed. The generator produces a magnetic field that generates electricity from the torque accumulated by the gearbox. The converting cabinets refine the raw electricity to meet grid standards, and have the ability to disconnect from the grid if a problem arises. Then, the power is funneled to the transformers, which ramp up the electricity from 690 to 3460V and send it to the grid. The cooling system’s main function is to cool off heated oil. Most of these parts require electricity, which is produced from the turbine or drawn from the grid when the turbine is not running. Wires run all around and into a hole in the main shaft designed for that purpose.

Here’s an almost finished nacelle.

After the nacelle is completed, two weather and corrosion resistant cover plates are installed and the nacelle and hub are carried out to the loading zone.

Blades

Blades consist of an amalgam of composite materials, including foam, glue, PVC, and are hollow. Rubber bricks are inserted to balance the weight of the three blades, which is very important for aerodynamics. The central support beam is made of cured glass and carbon composite with epoxy resin. The objective is to design lightweight but strong blades. They are shaped like jet wings to take advantage of the Bernoulli Lift. Three blades is accepted as the norm because it decreases vibration intensity, noise and wear while increasing overall efficiency on the two-blade. Adding more blades would only increase the cost at little increase in effectiveness. The average G8X blade measures 39m and weighs 7000kg, although newer models are heavier and can reach 60m. The numbers in the model name indicate the rotor diameter; G8X turbines carry 40m blades. Common problems with the blade include lightning strike and paint degradation. The former is mitigated somewhat with the Lightning Transmission System, which funnels the electricity to the ground immediately. However, lightning damage can still inflict significant damage and sometimes requires a full replacement. 3M industrial tape is applied to the leading end to reduce paint wear, and maintenance comes around every 6 months to reapply if necessary.

Towers

Towers are the only immobile parts in a wind turbine. The height of the tower determines how efficient the turbine will be. Generally, the higher the tower, the stronger the wind. The tower is a conical shape, with the stubbiest, thickest piece at the base to support 250T of weight. Every subsequent piece is taller and thinner. At the top, a weighted pendulum helps reduce shaking. Towers range from 67m to 120m, although the average cost-efficiency is around 78-80m. Flanges at both ends of a tower section allow the installation of bolts to fasten the sections. A ladder runs from the bottom to the top for maintenance; a worker has to climb vertically for up to 120m. To reduce this challenging task, platforms are available at every section as well as a seat in the last section. Climb Assist technology will pull 50% of the worker’s weight through the harness  when climbing, and there is a more expensive elevator option. Currently, tower sections are built entirely with welded steel plates.

Construction, Commissioning and Services

After all the parts are finished, the turbine must be transported, constructed, commissioned and maintained. The separate pieces are trucked to the wind farm, where assembly occurs. A concrete and cement foundation supports the tower. Each section of the tower is installed vertically, then a crane lifts the nacelle on top of the tower. The blades are inserted into the hub before lifting and joining with the nacelle. Various electrical cables must be connected, bolts fastened and parts checked. Then, inspectors install testing software and run trials and alarms, checking for failures, oil leaks and other problems. Once this step is over, the turbine is commissioned and ready for operation. Field inspectors check back after the first three months and every subsequent six months for maintenance work. Customer Service is available on call. Gamesa warranty runs from one to ten years and covers any repairs and maintenance. An extended warranty runs through the 20-year life of the turbine. Design upgrades are also available at a cost to the customer.

Project and New Development

Meanwhile, developers work on improvements and new designs. They must convert European standards to American standards, regulate maintenance, deal with customer support and modify repeatedly failing parts, design new parts and test them, design new turbines and balance cost, effectiveness and safety. CATIA is the primary tool for designing new parts and components. A component as complex as the hub or nacelle can take several years to complete. The new model is the G10X, which is already operational in Spain and produces 4.5MW, more than double that of the G8X. The rotor diameter is increased to 128m among a lot of updates on its predecessor. The tower sections are now split into sections and built with concrete instead of steel and the blades are split into two sections to make logistics feasible and costs cheaper. The FlexiFit crane can climb up the tower to do maintenance, making 100m tall and prohibitively expensive cranes obsolete. Various software AI improvements and digital features will also be implemented to increase safety, increase efficiency and reduce damage and failure. This new turbine design rivals the price of natural gas and is cheaper than new coal.

Conclusion

I conclude the internship with hopeful thoughts. I believe wind is one of the energies of the future. It requires no fuel, provides more jobs than competing industries and is already cost-effective. Offshore projects, the G11X and G14X, are already in development and will eliminate the land requirements. This is a promising company that will increase its influence in a fast-expanding industry. I want to thank all the employees of Gamesa for nicely answering my questions and educating me about what they know. Thank you for your time and patience!

In order of appearance:

Patrick Guo-Orientation, Nacelles, Gearbox, Supply Quality

Miguel Garcia-Construction and Commissioning

Mike Christman-Services

Tomas Espinola & Tarus Calhoun-Procurement

Kalash Jhamb-Electrical Components

Fernando Mendoza-Towers

Anirudh Rudrapatna-Project Development

Amin Vega-CAD and CATIA drawing

Dan Broderick-G10X and New Development

Muhammad Murtaz-Blades