China is introducing a stricter grid code that will reduce the risk of power outages at big wind farms, but will add costs and slow turbine sales.
The new code demands that projects use only turbines with low-voltage ride-through (LVRT) capability. This technology, which keeps turbines operating even after a large drop in voltage, has become increasingly vital following a series of major outages at wind farms this year.
On 17 April, 702 turbines tripped off the grid at a wind farm in Jiuquan, Gansu province, after two box transformers broke down, causing a dip in voltage. On the same day, 644 turbines had to be disconnected in Zhangjiakou, Hebei province, for the same reason. Two similar incidents occurred in Gansu in February.
Experts say none of the turbines installed in China before 2010 is LVRT-capable, yet wind power accounts for a fifth of total electricity generation in parts of Inner Mongolia and Gansu.
The final version of the code, expected in the next few weeks, will require LVRT tests for equipment at new wind farms. Turbine makers say some of the requirements could hurt their business. They are also under pressure to upgrade machines that have already been installed, even though this is not yet mandatory under the new code.
And industry sources say that existing wind farms without LVRT capability may be the first to be disconnected in the future when grid capacity is saturated.
“It’s a big deal. Everyone is talking about this,” says an adviser at one manufacturer.
Not all turbines have LVRT functionality. Fixed-speed turbines and older models using synchronous generators may be difficult to upgrade, says Shi Pengfei, vice-president of the Chinese Wind Energy Association. It is not clear how these machines could be adapted.
“They cannot just be removed,” says Shi. “There is technology that can be fitted to the substation to make the whole wind farm LVRT-capable, but it’s very expensive. It may not be economic to do that.”
For those turbines that can be upgraded, developers and suppliers are haggling over who should pay.
Although contracts typically did not stipulate LVRT technology, some turbine suppliers are offering add-on packages at their own cost to keep customers happy. “We think it should be our responsibility to upgrade them, and the developers appreciate this,” says Goldwind spokesman Thomas Yao.
The company has installed more than 3,000 of its 1.5MW machines in China, but Yao says upgrading the direct-drive machines will not cost a lot. “We already have this LVRT capability, it just needs to be activated.”
He estimates the cost at 10,000 yuan ($1,520) per turbine. Another manufacturer of gearbox turbines puts the figure at about 140,000 yuan.
Engineers have been working on upgrades for months, creating plenty of work for consultancies such as GL Garrad Hassan. “It’s an especially hot topic in Gansu province. We’ve had a lot of enquiries from there,” says Wan Chun, the firm’s business development manager in China.
With developers focused on updating equipment, new projects are on hold, slowing business for turbine makers, says Jens Olsen, Nordex’s chief executive in China.
For projects that do go ahead, suppliers need to show LVRT certificates. These are not so easily obtained.
In December, the National Energy Administration issued rules requiring each installed turbine approved after 1 January 2011 to have a certificate from a local authority proving LVRT capabilities. The China Electric Power Research Institute (CEPRI) is the only authority with a testing facility, and its resources are limited.
“The testing centre at Zhangbei [in Hebei] only has 30 slots and these have filled up quickly. Everyone is trying to figure out whether to get in the queue, or to come to agreements with the CEPRI to accept test certificates from international institutes,” says an insider at one manufacturer.
The CEPRI says it plans to add new testing facilities, but it is not known when these will be set up. About ten models have completed LVRT testing so far, says Wang Weisheng at the institute’s renewable-energy department. They include 1.5MW models made by Nordex and Ming Yang. But with 50 or 60 suppliers in China, the institute is under pressure, says Olsen. The tests can take more than two months, depending on the wind.
“We definitely see this [new grid code] as positive,” Olsen adds. “We should have had it much earlier. But there are bottlenecks right now.”
Foreign manufacturers are asking the CEPRI to accept certificates from international test centres to speed up the process. This would also reduce the risk of intellectual property leaks posed by installing a turbine for testing at the CEPRI.
Manufacturers need to find a solution soon, as developers are including requirements for LVRT in new tenders. Suppliers without an approved LVRT certificate could lose out, even if they have models certified by internationally recognised institutes.
“This code is making suppliers crazy. We need to wait for the new standards while at the same time line up for the new tests and negotiate with developers over who pays what,” says Yao.
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