Its proposals for up to 33 turbines at Dyfnant Forest, near Llangadfan, have been shelved, partly due to expected "lengthy planning processes".
The project was announced in 2008.
The company said it has decided to focus its onshore wind efforts on replacing turbines at Llandinam in mid Wales, subject to a planning decision.
"We have been an active wind power developer in Wales since 1992, and we hope that our association with renewable energy in the country will continue for many years to come," said UK managing director Simon Christian in a statement.
Wind farm plans in Powys have been ditched with ScottishPower Renewables saying it is no longer financially viable.