Kabushiki Kaisha Toshiba

The Tokyo Electric Power Company, Incorporated

Fumio Aoyama

Yoshirou Tanoue

Fumitoshi Ichikawa

Yukio Tokiwa

Tadayuki Kitahara

A device for suppressing voltage fluctuation and higher harmonics of a power source system which supplies power to a load with large power fluctuation and large harmonic current. The device includes a self-commutated converter arranged in parallel with the load and a control circuit for controlling the self-commutated converter. The control circuit includes a compensation current variable calculation circuit for calculating a plurality of compensation current variables based on electrical quantities of the power source system and the load, a compensation gain calculation circuit for determining at least one compensation gain based on at least one of the compensation current variable, and a current instruction value calculation circuit for calculating a plurality of respective current instruction values based on the compensation gain and a plurality of the respective current compensation variables. The control circuit also includes an overall current instruction value calculation circuit for calculating an overall current instruction value by combining the current instruction values, and a current control circuit for controlling an output current of the self-commutated converter based on the overall current instruction value.

Device for suppressing voltage fluctuation and higher harmonics

A power converting apparatus comprises self-commutated converter, fault current restricting device, fault detector, and cutoff circuit. Self-commutated converter converts AC power supplied from an AC power system into DC power and supplying the DC power to a common DC circuit, and for converting DC power supplied from the DC circuit into AC power and supplying the AC power to the AC power system. The fault current restricting device is inserted between the self-commutated converted and the DC circuit, and includes a diode provided to permit a DC circuit current to flow from the self-commutated coverter to the DC circuit, and a series circuit having a reactor and a DC power supply and connected in parallel to the diode. The fault detector detects a fault current generated when self-commutated converter is short-circuited. When the fault detector detects a short circuit occurring in self-commutated converter, the cutoff circuit cuts off power supply to that self-commutated converter. With this structure, the DC power supply supplies a circulating current according to a rated current of the self-commutated converter to the reactor and the diode.

Power converting apparatus capable of suppressing a fault current

A device for suppressing voltage fluctuation and higher harmonics of a power system which supplies power to a load with large power fluctuation and higher harmonic current. The device includes a self-commutated converter and a higher harmonic filter, both provided in parallel with the load. The device includes a first calculation circuit which calculates a reactive power consumed by the load based on a load current and system voltage and generates a fundamental harmonic current command value to compensate the reactive power. The device further includes a second calculation circuit which detects a higher harmonic current flowing out to the power system based on a current flowing from the power system and generates a higher harmonic current command value to suppress the higher harmonic current. The device further includes an adder which adds the fundamental harmonic current command value and the higher harmonic current command value to generate a current command value of the self-commutated converter. The device includes a control circuit which receive the current command value for controlling the self-commutated converter.

Voltage fluctuation and higher harmonics suppressor

A reactive power compensation device for a system including an AC power source and a load. The device comprises a first detection circuit for detecting reactive power in the load; a first reactive power compensation circuit, having a reactor, a thyristor and a capacitor, the thyristor being controlled based on the detected reactive power in the load; a second detection circuit for detecting total reactive power in the load and the first compensation circuit; a second reactive power compensation circuit having a self-commutated power converter connected in parallel to the load. The second compensation circuit is controlled to minimize the detected total reactive power in the load and the first compensation circuit.

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Tokyo, Japan

Fumio Aoyama