To reduce the level of higher harmonics, by reducing the capacity of a thyristor starting equipment as a whole plant series constituted with a plurality of shafts.

A thyristor starting unit 4 having an insufficient capacity for one shaft of a turbine generator uses two units of thyristor starting equipment (LCI-1, LCI-2), at the same time for one of the generator shafts during the start and rise of the speed of a generator shaft (G1) by the ON operation of a disconnector 3-3; one clock for arranging the control timing of these two thyristor starting equipment is commonly used; a current control signal for aligning the output waveform phases of individual thyristor starting equipment is prepared based on a signal from the clock; the two units of the thyristor starting equipment are controlled base on the current control signal; and an electric torque required for the start and speed increase for one shaft of generator can be generated.