Long-distance underwater power supply system

A long-distance underwater power supply system, being applied to a submarine observation system comprising a plurality of load nodes, wherein the power supply system comprises at least one terminal power supply and a plurality of branching nodes, wherein

• the terminal power supply is sequentially electrically connected to the plurality of branching nodes through a trunk cable, and is configured to output a constant current to the trunk cable;
• the plurality of branching nodes are respectively connected to the load nodes corresponding to the branching nodes, wherein each of the branching nodes corresponds to at least one load node, the branching node is electrically connected to the load node through a branch cable, and each of the branching nodes and each of the load nodes are respectively connected to an ocean ground, respectively, the branching node and the load node corresponding to the branching node returning currents through the ocean ground;
• and
• the branching node is configured to convert the constant current transmitted from the trunk cable into a constant-voltage current, and output the constant-voltage current to the load node.