In this scenario one of your ships needs to move forward towards the Black Carrier so that it can do "crowd controlling".
The best strategy to do crowd control is to prepare that armada by increasing the combat and aiming to acquire the "X-Trooper" special unit. This unit will allow you to actually kill 2 Raiders each round, effectively allowing you to gain more Astartium, get upgrades faster and control the flow of Raiders.
To accomplish that in the best way you need to start by first adding the "Scrapyard" Power Up to your armada. This will allow you to gain more Astartium since you will be doing the main "killing" in this Scenario.
Personally I will pick a Commander that gives a Research Lab upgrade and I would start with "Scrapyard" and "Astral Guardian" as the first two power ups. These will allow the armada to gain more Astartium from killing while at the same time repair damage. From then on I would only upgrade Starport until I got the "X-Trooper".
This scenario requires a lot of Fighting, so you should try and build "Combat Oriented" armadas.
Thanks, will have to give it a new go and try out your suggestions.