China

China

WindTech: CSIC ready to muscle in on 10MW offshore market

CSIC Haizhuang Windpower has ambitious plans to install 8MW and 10MW offshore prototypes in 2020. During his recent China visit, Eize de Vries talked to the firm in Chengdu about their latest products and development history.

Early start… CSIC Haizhuang Windpower installed two initial 5MW prototypes in 2012 (pic: LM Wind Power)
Early start… CSIC Haizhuang Windpower installed two initial 5MW prototypes in 2012 (pic: LM Wind Power)

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CSIC Haizhuang Windpower (CSIC HZwindpower) was set up in 2004 as a subsidiary of China Shipbuilding Industry Corporation (CSIC), a large state-owned industrial group.

Among other things, the parent company manufactures many key wind-turbine components, including tubular steel towers with a likely diameter of up to eight metres, heavy-duty castings (hubs, bearing and gearbox housings), welded frames, main shafts, gearboxes, generators, control systems, power converters and hydraulic systems.

CSIC HZwindpower is only a small player in offshore wind at present, with 152MW commissioned by November 2019, but it boasts some major milestones and has a measurable multi-megawatt-scale track record built from 2012, when it beat all local competitors by installing two offshore-dedicated 5MW high-speed geared H154-5.0MW prototypes, each with record 154-metre rotor diameter.

The turbines became part of the Jiangsu Rudong inter-tidal demonstration wind farm.

In the years that followed, this installed 5MW base was gradually expanded by another 24 units, and an enhanced 6.XMW prototype is planned before the year end or in early 2020 (see below).

CSIC HZwindpower’s latest and most powerful 10MW H210-10.0 product development features a super-size 210-metre rotor, offering a class-record low 289W/m2 specific power rating.

The official product release coincided with the annual China Wind Power summit in October in Beijing, at which the turbine model received design certification from the China Electricity Science Research Institute (CESRI), a certification body of China State Grid Co.

It not only has the largest announced rotor in China but (likely) for any 10MW turbine introduced globally.

There are currently three other machines in the 10MW range: Dongfang Electric Corp’s model with a 185-metre diameter, Siemens Gamesa’s SG 10.0-193 at 193 metres, and the MHI Vestas V164-10.0MW offering a 164-metre rotor diameter.

All are dwarfed by GE’s 12MW Haliade-X with its official 220-metre rotor.

The H210-10.0 MW turbine specifications are specifically aimed at favourable Chinese offshore locations with mean wind speeds above 8.5m/s (IEC class I), according to He Lizhi, CSIC Haizhuang’s vice general manager in Chengdu, Sichuan province.

"We are considering developing an uprated 12MW version in parallel, with an unchanged rotor diameter and the same mechanical layout for European and other international high-wind IEC I offshore markets," he says.

Medium-speed drivetrain

CSIC’s product manual indicates that both platform models share a compact semi-integrated medium-speed geared drivetrain with flange connections between the main components.

The first element appears to be a main shaft/main bearing unit in a common cast housing, bolted to a spaciously dimensioned cast main carrier. The additional main drive components are a two-stage planetary gearbox and a permanent magnet generator.

Another new model, with an 8MW rating, shares a comparable mechanical layout and drivetrain configuration, but with some different dimensions and main specifications.

This H185-8.0MW has a 185-metre rotor diameter (298W/m2) and is initially focused at the local market segment with IEC I wind conditions above 8.5m/s.

Both the 8MW and 10MW models likely incorporate two power converters located along each of the nacelle sides behind the generator.

The MV-transformer is mounted inside as well, but at a 90-degree angle to the nacelle sides in front of the rear cover.

"When we started developing the 8MW product about two years ago, very few local suppliers were capable of producing the required main components," Lizhi recalls.

"Development of the larger 10MW turbine started later and had to happen faster to meet our target of installing both prototypes before the end of 2020.

"The single biggest challenge for our 10MW machine turned out to be sourcing the roughly 103-metre long blades, because international procurement would have been too expensive and therefore was not an option."

Advanced blade

CSIC HZwindpower managed to find a local supplier capable of developing and producing a state-of-the-art blade made of advanced carbon and glass-reinforced epoxy composite.

Additional initial difficulties in sourcing main components for both new turbine models occurred with the gearboxes, rotor-hub castings, and for tower and substructure tubular-steel diameters exceeding roughly 8 metres.

"I could in this respect draw a parallel with the major supply-chain constraints we experienced when developing the 5MW H154-5.0 MW turbine in the 2010-11, including prototype assembly," Lizhi says.

"At that time there were hardly any local foundries capable of supplying the required hub castings, while today there is a wide choice in suppliers."

CSIC HZwindpower selected two gearbox suppliers for the 10MW turbine, the Nanjing High Speed Gear Manufacturing Company (NGC) and Chongqing Gearbox.

Gearbox input torque rating is comparable and well into the 13,000kNm-plus range.

This is about 30% higher than the current (likely) highest rated gearbox of the 10MW MHI Vestas V164-10.0 at 10.0MNm. (Input) torque is a function of power (P) divided by rotor speed (n), or in formula: T = f (P / n).

The substantial input torque difference for these two above competing 10MW turbine models can be largely explained through two main contributing factors.

The first is the much bigger rotor of the H210-10.0 MW (210 metres versus 164m), which thus turns slower for a given rated tip speed.

A common value is 90m/s for offshore wind, and among others pursued by MHI Vestas for the V164/V174 series and GE’s Haliade-X.

Second, to reduce the risk of leading-edge erosion damage, CSIC HZwindpower chose a rated tip speed below 90m/s, according to Lizhi, implying a further (relative) reduction in rotor speed.

Floating offshore

The company plans to enter the floating offshore wind market as early as 2021 with two different floater solutions, both in combination with a 5MW turbine.

The first floating solution is a semi-sub, the second a compact spar-type, probably with reduced draught.

"With each of these technologies we’re aiming at water depths over 50 metres, such as off the south China coast," Lizhi concludes.

Building know-how — Scaling-up from a 5MW platform

The H154-5.0 MW is a conventional offshore turbine concept with a head mass of around 600 tonnes. It incorporates a compact high-speed geared drivetrain with a single double-row roller-type rotor bearing, semi-integrated into a short hollow main shaft.

The latter is flanged to a conventional three-stage, CSIC-made gearbox with side torque supports, and the final main drivetrain element is a non-integrated permanent magnet generator (PMG).

The drivetrain layout, except the choice of PMG, bears a close resemblance to now-defunct German firm Bard Engineering’s earlier 5MW Bard 5.0 offshore turbine design (right), which had a smaller rotor diameter of 122 metres.

Two additional 5.0MW units for IEC IB/IIIB+ with a slightly reduced 151-metre rotor diameter were commissioned in 2015.

Another 19 renamed H151-5.0MW turbines followed in 2017, and two more this year. One enhanced H171-5.0 MW prototype for IEC IIIB+ has been operating since 2017.

The + stands for a built-in capability to survive extreme weather conditions such as those defined within IEC wind Class II (50m/s).

The model variant with an enlarged 171-metre diameter represents the latest 5.X MW platform expansion, which also encompasses the H128-5.X MW for high-wind IEC IB.

The firm made an evolutionary uprate of the proven 5.X MW drivetrain layout with the 6.X series, offering flexible 6.0-6.2MW rating.

An H152-6.X MW prototype for IEC IB is thought to have come into operation this year, while an H171-6.X MW sister model prototype for IEC S is envisaged by early 2020.

In 2014, the firm commissioned ten much smaller 2MW H102-2.0 units with a 102-metre rotor diameter for IEC IIIA in the Longyuan Rudong inter-tidal wind farm, following a 2010 offshore prototype.

The 2MW series has a conventional non-integrated four-point drivetrain layout with a main shaft supported by two rotor bearings, and DFIG.

Early partnerships

Lizhi explains that during its early years in the wind industry in 2004-06. CSIC HZwindpower lacked sufficient know-how to independently develop wind turbines.

It therefore teamed up with German engineering consultancy aerodyn energiesysteme to co-develop the 2MW turbine in multiple model variants for onshore and offshore, and with CSIC HZwindpower owning the full IP rights.

Another co-design cooperation was established with Dutch engineering consultancy Mecal for the H154-5.0 MW product development from 2010.

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