If you're just wanting an orchestra to perform your uncommissioned music, then they may charge a rate to print sheet music copies and otherwise prepare the piece. Especially for student pieces. Like, recording an orchestra for example typically costs 10s of thousands per hour.
In concert music, if they commission a piece, they would pay for that piece and then pay out performance royalties to the PRO on top of that.
Also in concert music, if they did not commission the piece, but choose to perform it in a concert, the composer is paid royalties through their PRO.
BUT I'm not aware of many orchestras outside of music college ones being in the business of playing concert pieces that that don't already come from classical repertoire, films or video games anyway.
In short: If it's for a concert and you're trying to get them to play your piece in it, they may want some amount of money to prepare the piece, but not a raw fee simply to "play" it. They have to pay to play it.
But it is a bit of a moot point. Most orchestras, at least that I'm aware of, won't even give an unknown composer consideration for concerts.