In Victoria, both the OC and the Committee can strike a special levy. Where the special levy exceeds the double the annual budget, a Special Resolution is required (s.24).
So, unless a Committee spending limit has been set by an Ordinary Resolution, up to twice the annual budget can be raised as a special by the Committee alone.
No additional formalities are required for Committee meetings that are considering striking a special levy although a good Committee would be keeping all owners informed.