$plaka = "01ADS000";
$plakaRegex = '#^(0[1-9]|[1-7][0-9]|8[01])(([A-Z])(\d{4,5})|([A-Z]{2})(\d{3,4})|([A-Z]{3})(\d{2,3}))$#si';
preg_match($plakaRegex, $plaka, $matches, PREG_OFFSET_CAPTURE);

if(count($matches)) {
    $newPlaka = $matches[1][0] . '-' . $matches[7][0] . '-' . $matches[8][0];
    echo $newPlaka;
} else {
    echo 'Hatalı Plaka!';
}