Toshiba Mitsubishi-electric Industrial Systems Corporation

Mitsubishi Electric Corporation

Kotaro Higashi

Shinzo Tamai

Yasuhiko Hosokawa

Sadao Funahashi

Toshiyuki Fujii

Osamu Mori

Kaho Mukunoki

Satoshi Azuma

Takushi Jimichi

Kimiyuki Koyanagi

Takeshi Kikuchi

Miwako Tanaka

Naoki Morishima

In a power conversion system in which one or more converter cells are connected in series to form an arm for each phase, a control device includes a voltage command generating unit for generating a positive arm voltage command and a negative arm voltage command for each phase. The voltage command generating unit includes an AC current control unit, a circulating current control unit, and a command distributing unit. On the basis of inputted voltage commands, the command distributing unit subtracts voltage drop portions due to inductance values in the arms from respective voltages assigned as outputs of the positive arm and the negative arm, to distribute voltage components, thereby determining the positive arm voltage command and the negative arm voltage command.

Power conversion system

A power conversion device performs power conversion between three-phase AC, and DC, and includes a positive arm and a negative arm for each phase, each of which includes one or more converter cells connected in series. A voltage command generating unit in a control device includes an AC current control unit, a circulating current control unit, and a command distributing unit, and generates a positive arm voltage command and a negative arm voltage command for each phase. In the circulating current control unit, a compensator calculates a first control command so that circulating current for each phase approaches a circulating current command value, a suppression unit generates a second control command so as to suppress a 2f component and a 4f component contained in the first control command, and then the first control command and the second control command are combined to generate a circulation control command.

Power conversion device

An electrical power converter includes: AC voltage terminals U, V, and W; DC voltage terminals P and N; a converter cell series unit composed of one or more converter cells connected in series between the AC voltage terminals U, V, and W and the DC voltage terminals P and N, each converter cell including a semiconductor element and a capacitor; and a first inductance connected in series to the converter cell series unit, between, of the DC voltage terminals P and N, a DC voltage terminal at the lowest potential with respect to the ground, and the AC voltage terminals U, V, and W.

Electrical power converter with a converter cell series unit

In a power converter which performs power conversion between plural-phase AC and DC, variation in voltage of the DC capacitor in each converter cell is detected, and when the variation exceeds a predetermined value, a DC voltage command value as a control target value in a DC voltage control unit which controls DC voltage between DC buses is corrected by being increased or decreased. Thus, when AC grid failure occurs, the capacitor voltage of each converter cell is maintained and the operation continuity is improved.

Direct-current power transmission power conversion device and direct-current power transmission power conversion method

An electric power conversion device includes a power conversion unit and a converter control unit. The power conversion unit includes three arms connected to an AC circuit. The converter control unit includes a phase DC voltage control unit, a negative sequence current command value calculation unit, an output current control unit, a circulating current control unit, a voltage command value calculation unit, and a gate signal generation unit, and imbalance of cell DC capacitor voltages among phases due to grid imbalance is controlled by circulating current and negative sequence current.

Electric power conversion device

An electric power conversion device includes a plurality of cell converters connected in cascade and including main circuits, drive circuits, and self-feeding devices for supplying power to the drive circuits by being supplied with power from the main circuits. The drive circuit is supplied with power via a first feed line from the self-feeding device in the corresponding cell converter, and supplied with power from the self-feeding device in another cell converter via a second feed line on which an insulation input/output circuit is provided. When the self-feeding device is abnormal, the drive circuit is supplied with power from the self-feeding device in the other cell converter, whereby the electric power conversion device continuously provides a desired output.

A power conversion device includes: a DC current calculation unit for calculating a circulating current component for each phase which circulates between the phases through first arms and/or second arms not via an AC power supply and a DC power supply; and a circulating current control unit for controlling the circulating current component for each phase so as to follow a predetermined circulating current command value, thereby reliably suppressing variation in voltages of DC capacitors of unit cells among the phases even in such a case where an impedance is additionally inserted in a DC circuit.

When switching control signals of self-excited semiconductor devices from OFF-control to ON-control, a control circuit controls the self-excited semiconductor device to be ON after a lapse of a turn-ON time from when a control voltage is applied to the self-excited semiconductor device. When switching the control signals of the self-excited semiconductor devices from ON-control to OFF-control, the control circuit controls the control signal of the self-excited semiconductor device to be OFF after a lapse of a turn-OFF time from when the control voltage is applied to the self-excited semiconductor device.

Power conversion apparatus having a three-level converter that converts AC voltage to DC voltage having three levels

A control device of a self-excited reactive power compensation apparatus controls a reactive current output from a self-excited converter to a power system. The control device includes a first reference generating unit, a second reference generating unit, and a selecting unit. The first reference generating unit generates a first voltage reference of an output voltage output from the self-excited converter, such that the reactive current detected by a reactive current detecting unit follows a current reference. The second reference generating unit generates a second voltage reference of the output voltage output from the self-excited converter, such that a value of the reactive current becomes a predetermined value. The selecting unit selects a maximum value from the first and second voltage references.

Growing community of inventors

Chuo-ku, Japan

Kotaro Higashi