There are many kinds of Power Generation Systems: coal-firing, gas turbine [with and without combined cycle], nuclear ,hydro, wind and so on.
Let’s say for a coal-firing power station you have: precipitators, coal-handling facilities, ash handling, desulphurization facility, chlorination, water desalination plant and other. You have to model each facility according to technological needs: indoor or outdoor , supply substations included or not and so on.Can you be more specific?