Aberdeenshire Council had refused permission for the substation at the tiny community of Blackdog, but the planning reporter appointed by ministers has upheld an appeal from the developers subject to 16 conditions.
Some 62 out of 85 local Blackdog residents had objected.
The Scottish Government approved the 11-turbine European Offshore Wind Deployment Centre (EOWDC) in March last year, but separate approval was required for the substation.
The Trump Organisation is convinced the EOWDC would blight its nearby £750m golf resort at Balmeadie.
EOWDC project director Andy Paine said developers would work with the relevant authorities to ensure effects of onshore activity were kept to a minimum.