Can I change normal plug to a 15amp round pin plug?
Nate Strickland's answer is correct for the USA.

If you are in the UK, you'd need a similar adapter



Stage Electrics

15 amp round pin plugs are used for stage work in the UK for the additional reason that our 13 amp standard power plugs have fuses in them. A blown fuse on a lighting grid is difficult to change quickly, so unfused plugs are preferred. In schools the smaller 5 amp round pin plugs were often used.