Is "The name is derived from the encounter of the three federal branches around the plaza: the Executive, represented by the Palacio do Planalto (presidential office); the Legislative, represented by the National Congress (Congresso Nacional); and the Judicial branch, represented by the Supreme Federal Court (Supremo Tribunal Federal)." a good answer to the question "What does the name 'Praca dos Tres Poderes' come from?"
yes