Hitachi, Ltd.

The Kansai Electric Power Co., Inc.

Hitachi Mitsubishi Hydro Corporation

Osamu Nagura

Akira Bando

Hiroto Nakagawa

Yasuteru Oono

Yosio Furukawa

Yasuhiro Yasaka

Shigehiro Kayukawa

Makoto Suzuki

Eiji Haraguchi

Shinsaku Hakuta

Eiji Tsuji

Keiji Saito

Hashime Nagai

Sadahiko Niwa

Junichi Shiozaki

Tadaatsu Kato

Ikuro Miyashita

Akira Momiyama

Hirotaka Akagawa

Kiyoshi Oka

In a variable speed generator-motor apparatus, a power converter includes six two-terminal arms each formed by serially connecting k unit converters that can output arbitrary voltage, an AC rotating electric machine includes an armature winding with 60-degree phase zone formed from a double layer coil, the armature winding being divided into first and second pole sides to form double star connection by binding neutral points and to be drawn out as two sets of three-phase terminals; three-phase terminals on the first pole side are connected to first terminals of three arms, and second terminals of the three arms are star-connected to a first terminal of a DC power supply; three-phase terminals on the second pole side are connected to second terminals of remaining three arms, and first terminals of the three arms are star-connected to a second terminal of the DC power supply.

Variable speed generator-motor apparatus and variable speed generator-motor system

An electric power generating installation has a plurality of generator/motor units, each of which has a motor for converting kinetic energy into turning torque, a generator connected mechanically to the motor and connected electrically to an electric power system for converting turning torque into electric energy. A control system is provided for controlling the motor and the generator in such a way that they can be operated stably and continuously. The control system controls the different generator/motor units in different control modes so as to minimize cross current and resonance or beat phenomena.

Electrical power generating installation and method of operating same

An AC-excited generator/motor apparatus comprising; an AC-excited generator/motor having an armature mounting thereon; an armature winding connected to an AC power system and a rotor mounting thereon; and an exciting winding excited by an AC current. An exciting device for supplying a controlled AC exciting current to the exciting winding comprises; a device for calculating a real slip frequency based on a difference between the phase of an armature voltage appearing on the armature winding and the rotational phase of the rotor; and a device for controlling the exciting current supplied to the exciting winding from the exciting means in response to a deviation of the real slip frequency from a predetermined allowable range of slip frequencies so as to restore the real slip frequency within the allowable range of slip frequencies.

AC-excited generator/motor apparatus

A generator-motor apparatus with economical protection measures for use in a variable speed pumping-up electric power plant, having a main transformer, a secondary winding of which is coupled to an electric power system, a power system breaker connected to a primary winding of the main transformer, a syncronizing breaker connected in series with the power system breaker, a generator-motor, a rotor of which is mechanically coupled to the pump-turbine and an armature winding of which is connected to the power system through the synchronizing breaker, the power system breaker and the main transformer, and an excitation circuit, including a frequency converter for supplying a field winding of the generator-motor with AC voltage of the variable frequency and a converter transformer for feeding the converter, which is branched from a junction of the power system breaker and the synchronizing breaker.

Power system and synchronizing breakers for a variable speed generator

A method of assembling a wound rotor of a vertical type adjustable speed electric rotating machine at a power house of a hydroelectric power plant, with the method including a layer of a rotor body on its side into a pit in the power house with a top surface of an outer circumference of the rotor body extending from the pit to a height sufficient to facilitate a carrying out of field coiling assembling operations by working personnel from a foundation of the power house whereby it is possible to limit an increase in the height of the power house to a sum of an axial length of the assembled rotor body and a height of a crane lifting jig.

Method of assembling wound rotor of vertical type adjustable speed

A variable-speed power generating system comprises a variable-speed generator electrically connected at its primary winding to an electric power system and its secondary winding to the electric power system through a frequency converter and mechanically coupled to a driver driving the secondary side thereof, a phase detector generating an output signal representing a slip frequency in response to the application of a first input having a frequency component of an output generated from the primary winding of the variable-speed generator and a second input having a frequency component corresponding to the rotation speed of the driver, a controller controlling the frequency converter on the basis of a reference phase provided by the output signal of the phase detector, and regulating means for controlling the frequency converter so that, when the variable-speed generator is disconnected from the electric power system, the frequency applied to the secondary winding of the variable-speed generator may not deviate from a predetermined allowable range of variable frequency operation of the frequency converter.

Variable-speed power generating system

A generator/motor system comprises a generator/motor having a primary winding and a secondary winding installed on the motor rotor coupled to a prime mover/load, a main circuit interposed between a power system and the primary winding of the generator/motor, an excitation circuit including a frequency converter inserted between a part of the main circuit and the secondary winding of the generator/motor, a frequency difference detector for determining the difference between the frequency of the power system and a frequency dependent on the rotational speed of the load, and a phase-shift control device for controlling the firing phase of the frequency converter in the excitation circuit by use of a signal from the frequency difference detector as a reference signal. In normal operation, a frequency signal following the frequency of the power system is produced, while at the time of a disturbance of the power system, the same frequency signal of the power system as before the disturbance continues to be produced thereby to keep the system in stable operation. For this purpose, a starting electric machine, a synchronous motor and a synchronous generator are aligned, and an output of the synchronous generator is applied to the frequency difference detector.

Variable-speed generator/motor system

An induction motor starting method comprises the steps of supplying a predetermined low-frequency current to the primary winding of an induction motor through a first cycloconverter having its input side connected to a commercial-frequency power source and its output side connected to the primary winding, supplying a voltage of a frequency from zero up to a first frequency through a second cycloconverter having its first input side connected to the commercial-frequency power source and its output side connected to the secondary winding, controlling the first cycloconverter to increase the frequency of the low frequency voltage supplied to the primary winding to the first frequency when the rotation speed of the induction motor reaches substantially a first rotation speed, and disconnecting the output side of the first cycloconverter with the primary winding to connect the output side of the first cycloconverter to the second input side of the second cycloconverter and connect the primary winding to the commercial-frequency power source when the rotation speed of the motor reaches substantially a second rotation speed.

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Katsuta, Japan

Osamu Nagura