The owners corporation or strata committee have the right to enter and inspect your home for the purpose of repairing common property and/or determining if such repairs are necessary.
However, if you refuse entry, they have to get orders from NCAT to enforce that right.
I can see the wisdom of them taking pictures of any problem areas, as that would assist with getting an estimate of the cost of required repairs if a large number of units are involved.
However, if this is all because they suspect you have done something to common property without permission, this takes on a slightly more sinister aspect.
But one way or another, you can be required to allow access to them and be fined if you refuse AND be liable for damages if they have to force entry when they have a legitimate order from NCAT and you still refuse access.
So the question is, why don’t you want them in your home and how badly are you prepared to block access?