According to Dai Huizhu, a professor with the China Electric Power Research Institute Leading Electric Power Research Institute (CEPRI), 598 wind turbines, totaling 840MW, were disconnected from the grid in Jiuquan, Gansu Province on February 24.
Additionally, in January, hundreds of turbines in Jilin Province met the same problem.
The problems have led some industry experts to question the long-term reliability of China’s turbines.
This February shutdown, arguably one of the most serious in the history of Chinese wind power, was caused by a "general grid voltage fluctuation". All the wind farms in Guazhou, a major part of the 10GW-level Jiuquan wind power base, saw some of their wind turbines disconnected.
An expert from State Electricity Regulatory Commission, Northwest China Branch, who is refused to be identified, said on March 27 that "the incident took place because of joint efforts of wind turbines, wind farm construction and management capacity. And these problems are popular in Chinese wind farms that are under construction or under operation."
"Although large-scale cut-away from the grid is unavoidable for wind power, this incident resulted from human errors than natural disaster," the expert said.
The absence of low-voltage ride-through (LVRT) capacity is blamed for the large-scale disconnection.
Wang Ningbo, director of the wind power technology centre of Gansu Grid, said: "Wind farm construction has surpassed grid construction too much. Wind farms are not harmonized with the grid and this will be a bottleneck for wind power industry development in China."
Wang said: "If the government does not make effective interference, such incident will happen frequently in the future." He said similar incidents have occurred many times since the first stage of the 10GW-level Jiuquan wind power base passed examination. But they were too small to have any effect.
China has not mapped a timetable for upgrading existing wind turbines with the low-voltage ride-through capacity.
Wang said it costs about CNY300,000 to CNY400,000 ($45,000 to $61,000) to upgrade one Sinovel 1.5MW wind turbine with the LVRT capacity.
See the upcoming May issue of Windpower Monthly for an extended version of this article