Ran out of metal plates for my tharkth, anybody know what specific system i can farm vandium ore?? 

It’s everywhere, really. Probably most common thing you can drop. Even in zone where station is.

really? cos what i found in the closest sectors was more nickle ore than vandium

You will always see more useless credit trash than materials. That’s just the way the game is. But it does indeed drop from literally everywhere. Just grind some T1 fire support or something. An hour or so of that is about 10-20 plates’ worth.