AC power systems around the world have different frequencies. Inverter grid synchronization with phase locked loops handles frequency and phase variation. What AC power system frequencies do you expect your power converter to deal with?
"Utility side" frequencies: 25 Hz, 50 Hz, 60 Hz, 240 Hz, and 400 Hz. Include a +/- 5 percent range for each, to cover system instabilities. "Harmonic" frequencies found on incoming line: 5th, 7th, 11th, 13th, 23rd, 25th, 47th, 49th for sure. Also highly likely to see additional harmonics - especially on small islanded systems - in the 71st-101st range as well, at significant levels, particularly when paired with active front end drive topologies.
I've seen 240 Hz AC power systems are used as the line frequency on some specialized projects; most of these fall under either the aerospace or military category. 25 Hz power systems are less likely to be seen, but correspond to early development in industries such as mining and paper, where local generation was built into the plant design to facilitate the original switch from mechanical to electric drive.