hm,
im not too sure how the convoy is getting its destination, as it appears to not be defined anywhere, but i assume you can do this:
this.convoyDestination = convoyDestination;
change the = convoyDestination; part to
= station name;
with station name being whatever it is you named the station.
EDIT: code for station
SectorEntityToken hegemonyStation = system.addOrbitalStation(system.getEntityByName("Corvus"), 45, 300, 50, "Orbital Station", "hegemony");
this puts it about roughly in the middle of the sun, the 300 is the distance from where it spawns, not too sure what the other numbers do, but one controls how many days it takes to complete an full circle.