The Energy Act 2016 transferred responsibility for deciding planning applications for onshore wind schemes over 50MW to individual local planning authorities. Prior to that the responsibility had been with the Secretary of State for Energy.
Section 77 of the Town and Country Planning Act 1990 enables my rt. hon. Friend the Secretary of State for Housing, Communities and Local Government to call in certain planning applications for onshore wind farms, for his own consideration.
A breakdown by year of all current and approved applications, including referrals, can be accessed on the REPD, which can be viewed here: https://www.gov.uk/government/publications/renewable-energy-planning-database-monthly-extract.