I served 18 years in a 15 to 30 year sentence I've been on parole for 7 &1/2years . Is it possible to file a motion to get time served on my sentence

The details on your question are a little short.  Just doing some math it appears that you have served 25.5 years of a 30 year sentence leaving you 4.5 years to serve on parole.  State parole cases are more dificult because if some of that term was served on a violation the board can take your street time away.  This has been held to be lawful on a number of occassions.  If my understanding of your facts is incorrect, forgive me, but more importantly you may want to contact a local attorney to go through all of the factors with you.  The Board is famously unlikely to shorten your sentence but you may have issues you failed to describe in your facts.