BOOM Logistics (Boom) completed work on installing 44 turbines at owner/developer Acciona’s 132MW capacity Mt Gellibrand wind farm (25 kilometres east of Colac, VIC) in June this year, with commissioning ongoing in July and ramping up to full capacity in August.
The 3MW Nordex AW3000 wind turbines have a rotor diameter of 125 metres, and are installed on an 87.5 metres (hub height) 4-section steel tower.
Boom undertook the full installation scope including: component offloads; component installation, and; electrical and mechanical fitment. In doing this, it providing client Acciona Energy with a turbine ready for commissioning.
Across the wind farm, Acciona established a total of 30 kilometres of internal roads to link the turbine sites, with this completed in October 2017. Footings for the turbines (over 15,000 square metres of concrete) were completed in the following month, after which turbine erection commenced.
Component delivery commenced in October, with installation commencing in November.
Boom’s heavy lift installation cranes for the project were: a 600-tonne Demag CC2800-1 Narrow Track lattice boom crawler crane rigged with 96 metres of main boom and a 12-metre wind jib offset at 10 degrees for lifting the tower sections, nacelle and hub; and a 500-tonne Liebherr LTM1500-8.1 AT crane in Y-guy configuration with the telescopic boom extended to 47.3 metres and a 63-metre luffing fly jib fitted for installing the three blades on each hub.
These cranes were supported by a 130-tonne Grove GMK5130-1 AT crane, 220-tonne Grove GMK5220 AT crane and 90-tonne Grove RT890E RT crane. These cranes assisted in setting up, pulling down and tailing loads with the main installation cranes.
Boom also completed all the component off-loads on the project across the various hardstands using two 200/220-tonne AT cranes, supported by both the 500-tonne LTM1500-8.1 and Boom’s 400-tonne Liebherr LTM1400-7.1 for offloading the 106-tonne nacelles.
The tower sections (bottom to top) comprised: 15.09 metres high, 61.6 tonnes; 21.07 metres, 56.8 tonnes; 24 metres, 49.5 tonnes, and; 25.34 metres, 39.6 tonnes.
The nacelle weighed 106 tonnes, with rigging bring the total lift weight to 123 tonnes. The typical lift radius for the Demag in undertaking these lifts was up to 22 metres, with the crane running 40 tonnes on the Superlift tray to provide lift safety not only in capacity but also in clearances.
Response to weather challenges
Boom, in seeking to increase efficiency and reduce the impact of inclement weather, adjusted its installation methodology shortly into the project. This change brought about a significant increase in production for the CC2800-1, with this crane focusing on full tower installation, followed by the critical nacelle and hub lift.
This allowed Boom to quickly move the CC2800-1 on to the next tower installation, while also allowing for the electrical installation to be completed ahead of the 500-tonne crane installing the blades. This meant that power supply was available for turning the gear on the rotor during the blade installation.
This change, made possible only due to Boom having access to the LTM1500-8.1, allowed this crane to be redeployed to focus on blade installation. Its ability to relocate quickly allowed Boom to take maximum advantage of ideal weather windows and install up to four sets of blades in a single week.
The installation method of the AW3000 tower meant that Boom did not have to wait for grout to cure and thus could control its destiny in the installation time and tensioning of the tower sections. Typically the Demag would install four towers, a nacelle and hub in under two days; with Boom continuing to tension tower flanges while the crane was relocated to the next hardstand – an exercise that would typically take half a day, aided by the narrow track functionality of the crane and its ability to walk on the site roads fully rigged.
The 500-tonne Liebherr used a specialised 22-metre spreader bar purpose-designed for installing the 15.6-tonne AW3000 blades (a 21.5-tonne load when rigging was taken into account). Blades were picked up at between 30 and 40 metre radius, and installed at a 32 metre radius. To enable blade installation, the nacelle must be able to yaw and rotate the hub to allow sequential blades. This specialist turning equipment was installed by Boom’s team of technicians.
As would be expected for a wind farm, strong winds impacted the lift program, particularly in May. The adoption of the 500-tonne Liebherr for blade installation allowed Boom to manage this and meet the commissioning requirements of Acciona.