Yes. If it is thirty minutes past seven o'clock, you would say 7:30.
You can say 15 past 7 for 7:15 or A quarter til 7 for 6:45.
In general, numbers up to 15 you can use "past the hour". Numbers after 45, you can use "til the hour". All else is pretty much stated as is. (But honestly, it doesn't really matter. ^^ You can say it's 30 minutes past the hour.)