There is no best software really. You need good models, generally speaking you don't rely on models in those kinds of situations as the real world tends to have too many bumps and curves to properly model in any detail in a simulator, even something as simple as a real world transformer is VERY difficult to properly model in a simulator.
I think your best bet for this kind of think, at least for something like a generator or a breaker would be to use a high precision voltage and current monitor on the device in question and record a details image of the stimulus you're trying to add in to your simulator. Then instead of simulating you're using a pre-recorded real world signal to feed into the simulation circuit. Main problem is interactions between those two circuits can't be dealt with, but neither can they be using models or even special software, the details are just too many to deal with.