Hitachi, Ltd.

Hitachi Mitsubishi Hydro Corporation

Takashi Oyake

Masaya Ichinose

Akira Bando

Yutaka Kimura

Yuuken Okano

In a variable speed generator/motor device including a variable frequency power converter, a direct current voltage device including a voltage type self-excited converter, an automatic voltage adjuster, and a converter current adjuster that controls unit converters, a first three-phase branch circuit is provided between the direct current voltage device and an alternating current system; a second three-phase branch circuit is provided between the variable frequency power converter and a three-phase alternating current synchronous machine; a first load switch is provided between the first three-phase branch circuit and the second three-phase branch circuit; a measurement current transformer is provided between the three-phase alternating current synchronous machine and the second three-phase branch circuit; when switching from a converter mode in which the variable frequency power converter drives the three-phase alternating current synchronous machine to generate power to a bypass mode, the first load switch is closed to stop a gate command to the unit converters; and when switching from the bypass mode to the converter mode, a current command value of the converter current adjuster is calculated from a current value of the measurement current transformer, the gate command to the unit converters is started, and the first load switch is opened.

Variable speed generator/motor device

An excitation device supplies a three-phase AC excitation current to a variable speed generator-motor, and controls the variable speed generator-motor based on a three-phase AC excitation current command value obtained by vector-synthesizing, based on a slip phase from an exciting phase detector, a torque direction excitation current command value from a power adjustment computing device, and a magnetic flux direction excitation current command value from a voltage adjustment computing device by an excitation current adjustment computing device. The variable speed generator-motor includes a power fluctuation suppression circuit that causes the torque direction excitation current command value fixed to a value before switching to follow a torque direction excitation current command target value calculated from an effective power by a predetermined conversion circuit, filter circuit, and limiter circuit during a synchronous operation in an operation control method for operating to switch a variable speed operation method and a synchronous operation method.

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Tokyo, Japan

Takashi Oyake