Are you asking questions about wind turbine manufacturing or wind power generation? What the two above said is not very comprehensive. According to wind turbine manufacturers, Sinovel, Goldwind and Dongqi are in the first tier, and Mingyang Wind Power, United Power and Shanghai Electric are in the second tier.
There are five major energy groups investing in wind power: Guodian Longyuan, Huadian, Huaneng, Datang, China Power Investment, Guohua, China General Nuclear Power, China Wind Power, etc. It's hard to say that the first three are relatively strong.