Hitachi, Ltd.

Hiromitsu Sakai

Masaya Ichinose

Motoo Futami

Shuji Katoh

Shigeta Ueda

Tomomichi Ito

Takashi Ikimi

Hidetoshi Aizawa

Masahiro Nagasu

Ryuji Iyotani

Akira Bando

Mitsugu Matsutake

Yasuhiro Kiyofuji

Shinya Oohara

Kazuhiro Imaie

Yasuhiro Imazu

Kojiro Yamashita

A commanded negative-sequence current is added to a commanded current so as to suppress double-frequency pulsation on the DC side. The commanded negative-sequence current is found from three values (i.e., the detected value of positive-sequence voltage vector on the power-supply side, the detected value of negative-sequence voltage vector, and a commanded positive-sequence current). Thus, the pulsations which occur on the DC side of a semiconductor power converter and which have a frequency double the power-supply frequency are suppressed even when the AC power supply is at fault while assuring stability of the current control system, thus permitting stable and continuous operation.

DC/AC power converter with DC side double frequency pulsation suppression caused by AC side faults

A wind power generation system includes an excessive current consumption device, an AC input of which is connected between a generator rotor and an excitation converter on a system failure to detect a DC voltage ascent of the excitation converter and operate a shunt circuit on the system failure.

Wind power generation system

In a wind power generation system, an energy consuming unit is connected to a DC part of a generator-side converter. A shunt circuit is connected between the generator-side converter and a rotor of an AC-excited power generator. In the event of system failure, the switching operation of the converter is stopped, the shunt circuit is put into operation, and the energy consuming unit is put into operation so that DC voltage (voltage of the DC part) is maintained within a prescribed range.

Wind power generation system and control method thereof

In a wind turbine generator system including an AC exciting converter a grid side converter, and a controller configured to control the AC-exciting converter and the grid side converter, the controller operates a short-circuiting circuit when decrease in the grid voltage and increase in the DC voltage are detected.

Wind turbine generator system

To shorten a startup interval to reach a synchronizing condition, a phase difference and an amplitude difference between the grid voltage and the stator voltage of one phase of a winding are obtained. The difference in amplitude is decreased prior to or in parallel to synchronizing the stator voltage with the grid voltage. The calculated compensation phase compensation value is used as an initial value for synchronizing at the next synchronizing operation.

A wind power generation system temporarily stops a power converter when a system disturbance occurs, and reactivates the power converter after detecting a solution of the problem of an influence (overcurrent of a stator, direct current component of a stator, overcurrent of a rotor, etc.) of a fault occurring in a doubly-fed generator during a system fault. During a system fault, a reactive current can be safely output from a doubly-fed generator to an electric power system without destroying equipment of the wind power generation system.

Wind power generation system and method of controlling power converter

In a wind power generation system, an AC input of a unit for coping with system faults is connected to an excitation converter and a DC port of the unit for coping with system faults is connected to a DC port of a converter through resistors. A plurality of energy consumptive circuits each constructed of a resistor and switching units are provided for the DC port of the unit for coping with system faults.

A semiconductor power converting apparatus including at least one series arrangement of MOS control semiconductor devices such as Insulator-gate Bipolar Transistors (IGBTs) or metal oxide MOS transistors which are respectively applied with a gate voltage under the control of corresponding a driver. The driver contains a supply line having a higher potential than a gate voltage of an IGBT coupled thereto when the IGBT is in a steady ON state, and is such that is causes an increase of the gate voltage of the IGBT in accordance with the current of the supply line when a potential difference between the power supply line and an emitter of the IGBT is constant and the collector voltage thereof exceeds a predetermined value under an ON state of the IGBT.

Semiconductor power converting apparatus

A power conversion apparatus has a circuit configuration in which a collector voltage of an IGBT is divided. It also has a unit which protects the IGBT against overvoltages applied to the collector by outputting a potential of a voltage dividing point to a gate of the IGBT. A case of a resistor on the high-voltage side of the voltage dividing point is fixed to an emitter potential of the IGBT.

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Tokyo, Japan

Hiromitsu Sakai