Having been involved for years in the energy industry I can assure anyone that GTM is not a known "research" company (hence not trustworthy). The "gold standard" for wind capacity installation, projections, etc., is the Global Wind Energy Council (GWEC), hands down. GWEC states in their most recent 2012 China report that "By 2015, the installed wind power capacity [in China] will reach 100GW."
Source: http://www.gwec.net/wp-content/uploads/2012/11/China-Outlook...
China's installed capacity in 2011 was 62.4GW. In 2012 it is projected that another 15-18GW will be installed; that's 80.4GW by year end 2012 (on the high end). If 150GW is expected by 2015, a net average of 23.GW need to be installed per year. That installation rate is unrealistic due to manufacturing constraints.