for writing power supply A:
create_power_domain TOP -elements {......}
create_supply_net A -domain TOP
create_supply_net VSS -domain TOP
set_domain_supply_net TOP -primary_power_net A -primary_ground_net VSS
create_supply_port VSS -domain TOP -direction in
create_supply_port A -domain TOP -direction in
add_port_state VSS -state {state1 0.000000}
add_port_state A -state {state1 1.080000}
connect_supply_net VSS -ports VSS
connect_supply_net A -ports A
For writing power supply B: