A power generation and distribution system for a drilling rig includes (1) an AC bus and a DC bus, (2) an AC generator electrically connected to the AC bus, (3) an AC bus load electrically connected to the AC bus, (4) a first power transformer configured to convert a plurality of voltage phases of the AC bus into a plurality of corresponding secondary side voltage phases, (5) a first unidirectional AC-DC power converter connected between the secondary side voltage phases of the first power transformer and the DC bus, (6) one or more DC bus loads connected to the DC bus, and (7) a second AC-DC power converter connected between the DC bus and at least one of an auxiliary transformer winding of the first power transformer and a second power transformer for supplying power from the DC bus to the AC bus.