After a five-year hiatus, country duo Sugarland is back with the bright, poppy and aptly named “Bigger.” Jennifer Nettles still has a big, twangy voice that shines on all the big, Celine Dion-ish choruses on the record. Sugarland landed back on country radio this year with “Babe” featuring Taylor Swift. Nettles and Kristian Bush aren’t skittish about returning to state fairs after their stage at the Indiana fair collapsed in 2011, killing seven people. Opening are buzzed-about Lindsay Ell and Michigan-bred Frankie Ballard, known for “Sunshine and Whiskey.” (7:30 p.m. Aug. 24, grandstand, $57-$67,