Abstract: A secondary magnetic excitation generator-motor device that inputs a first ignition pulse command to a three-level NPC power converter such that a detected excitation current value corresponds with an excitation current command value, the secondary magnetic excitation generator-motor device having a function of identifying a first phase, a second phase, or a third phase in descending order of a current absolute value, wherein a pulse switch to output an ignition pulse command to the three-level NPC power converter switches the ignition pulse command to the second ignition pulse command when a current absolute value exceeds a set overcurrent level 1, and switches the ignition pulse command to the first ignition pulse command when current absolute values for three phases are all equal to or smaller than a set overcurrent level 2.

Abstract: A variable speed pumping system includes a generator motor including a frequency converter, in which the variable speed pumping system, in the pumping mode, supply a power command to the generator motor to perform power control, and the power control correction signal generator adds a value obtained by multiplying a signal based on a difference between the power input command and an actual power input measured by a power detector in the pumping mode by a constant gain to a signal based on the deviation and inputs the added value to an integration control element to generate the power control correction signal based on an output signal of the integration control element.

Abstract: 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

Abstract: 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.

Abstract: 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.

Abstract: A variable-speed pumped storage power generation apparatus sets a maximum change rate of a power output command constant when a slip frequency is within a normal operating range, limits the maximum change rate of the power output command by multiplying the maximum change rate by a value in a range of one to zero when the slip frequency is within a range falling below a lower limit of the normal operating range by a predetermined value or less or within a range exceeding an upper limit of the normal operating range by a predetermined value or less, and limits the maximum change rate of the power output command by multiplying the maximum change rate by zero when the slip frequency is in a range falling below the lower limit by the predetermined value or more or in a range exceeding the upper limit by the predetermined value or more.

Abstract: A pumped storage power plant performs a pumping operation by using a pump turbine, upper and lower regulating reservoirs. An upper space of one of the reservoirs is sealable. The pumped storage power plant detects an air pressure in the upper space, first and second water levels of the one and the other reservoirs. A controller of the pumped storage power plant obtains information of the detected air pressure, first and second water levels, and an electrical energy input from an external grid and used during the pumping operation. A calculation water level of the one reservoir is calculated by using the first water level and the air pressure. The controller adjusts the air pressure such that a difference between the second water level and the calculation water level becomes a desired difference that is determined by a characteristic of the pump turbine depending on the input electrical energy.

Abstract: A rotating electrical machine is provided in which, even when torque from a water turbine is reduced and reverse torque is applied due to load cut off, a rotor core is not eccentric to spider arms. The rotor of a rotating machine includes a vertical rotating shaft, spider arms extending radially from the vertical rotating shaft, and a rotor core component provided to the outer circumference of the spider arms. A T key and cotters are inserted into and secured to a key way provided to an abutment surface of the inner circumference of the rotor core component and the top end of the spider arm. A plate spring is mounted to a surface of the spider arm, the surface facing a rotational direction for electrical generation. The plate spring has one side engaging the spider arm, the other side engaging the rotor core component, and a middle portion bolted from an opposite surface of the spider arm.