A ship comprising: a power grid; one or more generators (G1,..., Gn) which are connected to the power grid and are configured to supply electricity to the power grid; a high-capacity battery which is connected to the power grid and configured to be charged with electricity supplied from the power grid or discharged to supply power to the power grid; a plurality of load components which are connected to the power grid; and a controller configured to provide a generator control signal (CS_G) to each of the generators (G1,..., G n) and configured to provide a battery control signal (CS_B) to the high-capacity battery, and which is connected to the power grid via a sensor, wherein the generators (G1,..., Gn) include a first generator and a second generator, wherein the controller is configured for receiving generator load information (L_G) from the generators (G1,..., Gn) and for calculating a current load (L_C) and an average load (L_A) by sensing a voltage of the power grid and for controlling the generators (G1,..., Gn) to handle the average load (L_A) and the high-capacity battery to handle a difference load between the current load (L_C) and the average load (L_A), wherein the generators (G1,..., Gn) include a first generator and a second generator, wherein when the ship operates a dynamic positioning, operation by using auxiliary power units in order to maintain its balance against dynamic changes in its position and angle over time, and characterized in that the controller is configured to calculate the average load (L_A) by averaging random samples of the current loads (L_C), which have been calculated before a current time, over an arbitrary time period, and wherein the average load (L A) represents an average tendency of the fluctuating current loads (L_C). 5 a power grid; one or more generators (G1,..., Gn) which are connected to the power grid and are configured to supply electricity to the power grid; a high-capacity battery which is connected to the power grid and configured to be charged with electricity supplied from the power grid or discharged to supply power to the power grid; a plurality of load components which are connected to the power grid; and a controller configured to provide a generator control signal (CS_G) to each of the generators (G1,..., G n) and configured to provide a battery control signal (CS_B) to the high-capacity battery, and which is connected to the power grid via a sensor, wherein the generators (G1,..., Gn) include a first generator and a second generator, wherein the controller is configured for receiving generator load information (L_G) from the generators (G1,..., Gn) and for calculating a current load (L_C) and an average load (L_A) by sensing a voltage of the power grid and for controlling the generators (G1,..., Gn) to handle the average load (L_A) and the high-capacity battery to handle a difference load between the current load (L_C) and the average load (L_A), wherein the generators (G1,..., Gn) include a first generator and a second generator, wherein when the ship operates a dynamic positioning, operation by using auxiliary power units in order to maintain its balance against dynamic changes in its position and angle over time, and characterized in that the controller is configured to calculate the average load (L_A) by averaging random samples of the current loads (L_C), which have been calculated before a current time, over an arbitrary time period, and wherein the average load (L A) represents an average tendency of the fluctuating current loads (L_C). 5