System and method for adding a high voltage dc source to a power bus

A system for connecting first and second high voltage direct current (HVDC) sources in parallel to a bus including a positive rail and a negative rail, the first HVDC source having a first positive output line and a first negative output line and the second HVDC source having a second positive output line and a second negative output line, the system including:

• one or more contactors connecting the first HVDC source to the bus such that the first positive output line is connected to the positive rail and the first negative output line is connected to the negative rail;
• a bus coupling circuit located between the second HVDC source and the bus that, in operation, couples the second HVDC source to the bus such that first and second HVDC sources are in parallel, the second positive output is connected to the positive rail and the second negative output is connected to the negative rail,
• the bus coupling circuit including:
• a positive line coupler and a negative line coupler, the positive line coupler including a first auxiliary contactor and a first inductor connected in series and a first main contactor connected in parallel with the series connected first auxiliary contactor and first inductor, the negative line coupler including a second auxiliary contactor and a second inductor connected in series and a second main contactor connected in parallel with the series connected second auxiliary contactor and second inductor;
• and
• a controller configured to:
• close the first auxiliary contactor to connect the second positive output line to the positive rail through the first inductor;
• close the second auxiliary contactor to connect the second negative output line to the negative rail through the second conductor;
• and
• close the first and second main contactors after a specified time has elapsed after the first or second auxiliary contactors were closed.