Non-standard installations, poor components and breakdowns have led to widespread instances of turbine failure, both as a consequence of technical malfunction and towers collapsing.
So far this year, Jiuquan in north-west Gansu province, the home of China’s first 10GW wind-power project, has witnessed 35 electrical equipment malfunctions, according to China’s electricity regulator State Electricity Regulatory Commission (SERC).
The malfunctions — all caused by transformer breakdowns — led to four large-scale disconnections from the grid involving 400, 598, 702 and 1,278
These incidents, according to SERC,have exposed major problems in China’s booming wind-power industry, particularly the absence of low-voltage ride-through (LVRT) capability in wind turbines, a necessity to ensure grid safety. LVRT provides wind turbines with the capacity to maintain continuous operation during and after precipitous voltage dips. LVRT-capable wind turbines allow the power grid to be adjusted more quickly and improve its overall safety and stability.
Liu Qi, deputy director of the National Energy Bureau (NEB), says: "The accidents take place partly because we emphasise the construction of wind farms on a large scale but neglect product quality and management. They also show we have poorly developed standards."
Until now, China has had around 200 wind-farm technical standards, mostly introduced from foreign countries and not suitable for the country’s conditions or circumstances.
New grid-access standards
Tied in with the issue of product quality and standards is the issue of grid access. China’s transmission network has not kept pace with the country’s rapid development of onshore capacity.
By the end of last year, around one third of the 31GW of wind turbines connected to the grid in China were laying idle. However, Liang Zhipeng, a deputy director of the new energy and renewable energy department at NEB, says despite these problems China’s wind-farm operators have reached an agreement on grid access with state transmission firm State Grid, which has pledged to accept 100GW of wind power to the grid by 2015. "Our present task is to make sure the 100GW of wind turbines operate safely and stably on the grid," Liang adds. "Therefore, it is imperative to establish and implement grid-access standards."
In August, NEB approved and published 18 new technical standards on the wind-power industry that will take effect from November. They relate to grid access, turbine-status monitoring, wind-power quality and equipment manufacturing. One defines the technical specifications for the design of grid access for large-scale wind farms, and requires all wind turbines to have LVRT capacity for access to the grid.
Most of China’s 34,000 wind turbines do not have this technology as it was not previously required. But the absence of LVRT capability is more likely to cause disconnections in the future if the grid continues to experience power dips, industry officials have said.
And, since April, Goldwind, Sinovel, Dongfang Electric, XEMC, Nordex and Vestas have begun modifying their turbines to include LVRT technology. Next to the cost of a wind turbine — tens of millions of yuan — the CNY 200,000-300,000 ($31,300-47,000) figure for modifying one with LVRT capability is affordable for wind-farm developers, says Liang. The addition will increase the life span of a machine and be good for long-term stablility, he adds.
In order to gain a clear idea of the status of operational wind farms, SERC embarked on a two-week safety check across the industry in mid-August, focusing on the modification of LVRT capacity.
In addition to establishing and implementing new technical standards, China has tried to ensure grid access by putting wind power under a unified state plan. Under the Renewable Energy Law, created in 2005 and amended in 2009, wind farms constructed with state approval are guaranteed access to sell all their wind power to the grid.
As the Chinese wind-power industry is still in its infancy, local governments have been actively encouraging investment in the sector and have approved a great number of wind-power projects under 50MW. This is neither in accordance with the state’s national development plan for new energy nor with the country’s power-grid planning, and results in inland wind farms having difficulty gaining access to the grid.
Local governments have announced over 40GW of wind-power projects, says Liang. If they are all built, many will be unable to access the grid.
To solve the problem, the NEB is now tightening control on expansion by reducing targets for new capacity. In August, it announced 29GW of planned wind-power projects nationwide, the first batch for the next five years. The targeted installed capacity has been distributed to local provinces and construction of the projects will be completed before 2012. Apart from these projects, says the NEB, all local-government wind-power projects will not be included in the grid-access planning of State Grid and will no longer receive subsidies for electricity generated by renewable energy.
The NEB will issue the second batch of quotas for wind-farm construction early next year, says Liang. "Our objective is to keep 20GW of new wind farms under construction, while ensuring more than 15GW installed capacity annually," he adds. "This pace will harmonise wind-farm construction and grid construction and guarantee achieving the target 100GW of turbines connected to the grid by 2015."