Netherlands

Netherlands

Enercon uses self-climbing crane to install EP5 turbines

Proof-of-concept shows that second-generation self-climbing LCC140 crane can install complete 4-5MW-plus EP5 turbines

Enercon used the LCC140 cranes to install three E136 EP5 turbines in Eemshaven, Netherlands (pic: Klaas Eissens)
Enercon used the LCC140 cranes to install three E136 EP5 turbines in Eemshaven, Netherlands (pic: Klaas Eissens)

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Germany-based Enercon has built two LCC140 self-climbing cranes, each enabled to install turbine models from its latest EP3 and EP5 platforms — including the latest E-160 EP5 E2 and the upcoming flagship E-160 EP5 E3 with the new E-nacelle, which will be the company's most powerful offering at 5.56MW (see E-160 EP5 section below).

Proof of concept

Each LCC140 crane has a hoisting capacity of 140 tonnes "below the hook" — excluding the weight of the unit's hook and cables. One LCC140 crane was deployed to install the first of three E-136 EP5 turbines at a project in the Dutch port of Eemshaven.

This initial installation trial process also served as the proof-of-concept trial for the new LCC140, explains crane specialist and lead engineer Henk Hendriksen, a senior member of Enercon's Dutch research and development (R&D) team in Barneveld, central Netherlands.

"After this full trial installation process involving all tower segments, the nacelle rear end, generator, hub and blades was successfully completed, the same crane is redeployed to install the second turbine, while the other LCC140 installs the third turbine of this project," Hendriksen says. "All three come with a 132-metre hub height and in a standard combination with our in-house developed, bolted modular steel towers (MSTs), which is a key feature of this fully integrated concept."

The next deployment for the self-climbing LCC140 cranes is a 21-turbine wind farm with E-136 turbines located in the same coastal Eemshaven region. In this case, 16 of the turbines — all with a hub height of 155 metres — will be installed with LCC140 cranes, and the remainder using conventional crawler-type cranes.

The initial conceptual ideas for this clever, innovative self-climbing crane concept originate from former Dutch wind pioneer Lagerwey and evolved into the first LCC60 product development in 2015/16. The crane was developed with Lagerwey's 2-2.6MW LP2 series in mind, especially the L100-2.5MW volume model. As with the LCC140, the number in the name refers to the maximum 60-tonne hoisting capacity below the hook.

Standard combination

"Our small core team developed the LCC60 together with three external companies, including a specialist firm for the mechanical design," Hendriksen explains. "A key system feature is that this self-climbing crane comes in a standard combination with the bolted modular steel tower (MST).

"To deliver proof of both the main principle and the concept, we installed a full LP2 turbine, including all tower segments, nacelle rear end, generator, hub and blades", he adds.

The Dutch supplier carried out a second proof-of-concept installation trial in spring 2017, this time with the latest 4.0-4.5MW LP4 prototype in Eemshaven. However, because the LP4 direct-drive generator mass by far exceeded the LCC60's maximum hoisting capacity, this essential part of the prototype installation process had to be carried out using a conventional crawler-type crane.

Enercon acquired Lagerwey and all of its intellectual property, including the patented LCC60 concept, in late 2017. Development of the enhanced LCC140 (see "Perfect harmony", below) commenced in 2019 under the wings of — and enabled by — the new owner's more comprehensive resources.

Most other LP2 turbines, now a phased-out platform, were destined for Russia and put atop standard tubular steel towers. These 100-plus turbines were produced in Enercon factories and only installed in the last few years.

The next deployment planned for the LCC60 crane is a space-constrained three-turbine project in Eemshaven with 2.5MW L100-2.5MW turbines being installed on the Oostpolderdijk flood defence facing the Ems river in the German-Dutch border area.

Complex sites

"We further found that the LCC technology offers particular benefits at complex sites," Hendriksen says. "One of the three E-136 Eemshaven locations had limited construction space and was situated close to a roundabout plus access roads, for example. If we had used a conventional crawler-type crane, the roundabout and access roads would have had to be closed to traffic during the entire installation period."

Blade lifting is the most critical operation with any crane, because it involves the longest hoisting distance measured from the tower centre, according to Hendriksen. Also, a blade always generates lift, whereby the aerodynamic load centre is inherently out of balance with the blade's centre of gravity. This induces a continuous up and down movement of the blade while hanging underneath the crane beam.

Enercon foresees the LCC's blade lifting capabilities (left) to be one of its strength in cutting installation time and costs compared with conventional cranes (right) (pics: Klaas Eissens)

"The most important learnings from turbine installations using the LCC60 and LCC140 models is finding the right balance between achieving the lowest extra costs for crane fixation points (see Perfect harmony section, below) with the maximum benefits from the self-rising crane. These holes made in the tower walls must be reinforced at both sides by steel plates to restore the original strength and retain the tower's certified (fatigue) design life. The extra investment for crane points with the LP2 series MSTs turned out to be too high, for instance.

"Fewer waiting days for blade lifts is the single biggest time saving when deploying the LCC140, but there are many other variables to consider, depending on project-specific circumstances", he explains.

The aim for the LCC design was never to compete against conventional cranes under all circumstances, Hendriksen adds. Rather, the team worked with two specific main development drivers. The first is to achieve the highest possible benefits at sites not suitable for normal cranes. The second is to actively anticipate at future trends as hub heights — now already in the 150-160-metre-plus range — continue to increase, pushing up deployment costs for conventional cranes to excessive levels. Hendriksen believes the LCC-concept could be scaled up further.

Systems integration

"One next main challenge is working towards an even higher degree of systems integration during the entire wind-project building process. Another is to further optimise the cost-critical connection between the crane and tower and, as part of this process, to continuously evaluate the price to pay for the added benefits", he concludes.

Perfect harmony — How the modular steel tower and LCC60/LCC140 work together

All wide-base Enercon modular steel towers (MSTs) are composed of pre-bent coning steel sheets, each measuring 2.8 by 12 metres, around 20mm thick and already incorporating precision pre-cut holes for the vertical and horizontal bolt joints. The assembly process starts by bolting these individual elements together in tapering full circle sections, whereby the section diameters decrease with height.

An essential feature for the combined tower-crane system is that all individual MST-sections incorporate three levels of large pre-cut holes in the mantle bottom area for LCC60/LCC140 mounting.
At each level, these holes are distanced at -90 degrees, neutral, and +90 degrees around the circumference. Neutral is the position opposite the main crane body central axis.

In total, six holes — three at each elevation — serve as climbing-crane attachment points and are structurally reinforced by steel plates on both sites for this reason. Two additional stiffener beams interconnect the central (neutral) hole, with holes two and three together forming a V-shape that offers extra structural strength and optimal load transfer between tower and crane.

At the beginning of each full turbine installation process, a small crane installs the initial three MST bottom sections, creating a "start" mounting platform for the self-climbing crane.

Bringing in all components for a complete LCC140 crane system to a construction site requires 11 road transports, including one with a total 80-tonne load. Like the smaller LCC60, the LCC140 is designed according to European standards.

The roughly 30-metre long central main body incorporates four hydraulically operated side "gripper arms" at two separate vertical levels, with around 24-metre interspacing, a distance that spans the distance of two full MST sections but is actually spread over three sections.

Gripper arms

During any hoisting operation, all four gripper arms and central mounting points between the crane body and tower are closed and locked. When the crane is brought to the next installation position, the side gripper arms are released, before the central body moves up one tower section enabled by another hydraulic system.

Rotation of the "split" lattice-type crane boom atop the upper crane body is enabled by multiple slewing motors. New for the LCC140 is an incorporated horizontal lifting beam for single blade installation mounted above the crane hook that has the ability to actively rotate around its central axis.

LCC60 and LCC140 hoisting operations are remotely controlled from ground level with the aid of cameras attached at essential positions of the crane. Many built-in safety functions thereby determine when a hoisting operation is allowed to commence.

E-160 EP5 prototype marks progress towards quick commercialisation

The E-160 prototype was upgraded to the 5.5MW E2 model using a conventional crane, but the LCC140 could be deployed in future as well (pic: Klaas Eissens)

Enercon completed the upgrade of its existing 4.6MW E-160 EP5 E1 prototype into the more powerful 5.5MW E2 with unchanged rotor size on 23 April, with commissioning now in progress.

The process involved replacing the permanent magnet generator (PMG) and hub, plus enhancing the tower-base-located E-module that incorporates all power electronics. The E-160 E1 foundation, tower and machine house remained untouched. The E2 is already a fully instrumented existing turbine, with for instance sensors, and/or strain gauges attached to critical components. The commissioning process will therefore be much faster, which means trial operation can start sooner.

At similar sites with 7.5m/s mean wind speeds, the E-160 E2 will produce over 21,534MWh annually — about 9% more than the initial E1 (19,615MWh).

The cumulative EP5 order intake, with the bulk for the flagship E-160 model, is already "significantly above 2GW", according to the company. Several large projects are about to start in Vietnam, Canada and Chile, plus many small and mid-sized projects featuring the E-160 in Germany.

The existing 4.6MW E-160 EP5 E-1 prototype was upgraded to the 5.5MW E-160 E2 with a new generator and hub plus enhanced E-module (pic: Klaas Eissens)

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