Lya Station Alpha was a Federation starbase to which the Enterprise-D carried survivors of the attack on Solarion IV in 2368, and where Admiral Kennelly gave Picard his orders concerning Bajoran militants.
The station appears in the Next Generation episode Ensign Ro. After a Federation colony on Solarion IV is destroyed and a Bajoran group claims responsibility, the Enterprise brings the survivors to Lya Station Alpha. There Picard meets Admiral Kennelly, who is suffering from a Cardassian virus and tells him to find the militant leader Orta and bring him in.
Kennelly also assigns Ensign Ro Laren, released from the stockade on Jaros II, to the mission, over Picard's objections. He does not reveal that he has made a private arrangement with Ro, or that he is working with the Cardassians.
The mission that begins at the station ends with Kennelly's scheme exposed and with Ro choosing to stay aboard the Enterprise.