^Actually, Voyager didn't even need to bother with ports to make repairs. The ship could land. They even showed it being repaired on the surface of a planet once.
They also explained in "Innocence" that Voyager was self reliant up to a point. Voyager is a deep space exploration/scouting vessel. It's was designed to be faster, stronger & self reliant because it designed to inter areas of space where it would get little or no support from other ships. It's first mission was into the Badlands where other Starfleet ships couldn't go. The one we saw on DS9 went into Romulan space-A.K.A. deep and potentally hostile territory.