The 600MW unit is directly connected to the step-up transformer, which is the wiring of the generator's step-up transformer group?
The high voltage side of the step-up transformer is usually 3/2 wiring
Generally speaking, incoming and outgoing lines are power lines and outgoing lines are load lines
2 × 600 MW means 2 incoming lines. Outgoing lines depend. how many lines you connect to the electrical system.