PURPOSE: To enable the continuous parallel operation of a shaft-driven electricity generator and an exhaust-gas-turbine-driven electricity generator and reduce fuel, by using an eddy current coupling to connect the shaft-driven electricity generator to the shaft of a main engine which drives the generator, in a method of supplying electric power in a ship through the combination of both the electricity generators.

CONSTITUTION: When electric power load in a ship is not higher then the output of an exhaust-gas-turbine-driven electricity generator 7, only the generator 7 is put in operation to bear the fluctuation in the load. When an automatic controller 14 has judged that the load in the ship cannot be borne only by the exhaust-gas-tubine- driven electricity generator 7 due to the load increase or the like, the single operation of the generator 7 is automatically shifted to the parallel operation of the generator 7 and a shaft-driven electricity generator 1 in accordance with an instruction from the controller 14. At that time, to control the operation of the generator 1, the slippage of an eddy current coupling 4 is regulated by an exciting current EXI from the controller 14. If the slippage of the coupling 4 is increased, the output of the shaft-driven electricity generator 1 is reduced. If the slippage is decreased, the output is augmented.