only had 2 times where trolls attack.
first time i ignored them and they kind of got stuck due to water being near my house on 3 sides.

Els i think a strategy to keep them away is to plant a long line of trees and use them as a wall kind of thing.
And ofcourse some spike weapons.
And if they attack and get though then make them follow you away from your home so you wont have it destroyed.
Better to just run and die vs having your base destroyed and then you can pickup you gear in a few minutes once the troll event is over.
Els deep moats also work.
Or shoot an arrow at each troll and make the follow you to your ship and sail a bit away.. Then shoot them from a safe distance while standing on your ship.