Abstract: A power conversion device includes a first control device to an m-th control device that are capable of communicating with each other. A k-th control device transmits specific information to control devices other than the k-th control device among the first control device to the m-th control device. The specific information includes voltage values of a plurality of unit converters included in a k-th cell set in each of a first arm to a third arm. From each control device other than the k-th control device among the first control device to the m-th control device, the k-th control device receives specific information including the voltage values of the plurality of unit converters. The k-th control device calculates a phase representative value of the voltage values of the plurality of unit converters included in each of the first arm to the third arm.

Abstract: A reactive power compensation device includes a power converter and a converter control unit, and compensates reactive power of an AC power grid by output reactive power of the power converter. The converter control unit includes an AC voltage detection unit and an output limit unit. The AC voltage detection unit detects voltage information of the AC power grid to which the power converter is connected. The output limit unit determines whether or not the output reactive power of the power converter needs to be limited, on the basis of the voltage information detected by the AC voltage detection unit, and in a case where the output reactive power needs to be limited, limits the output reactive power of the power converter.

Abstract: A power conversion device includes a first control device to an m-th control device that are capable of communicating with each other. A k-th control device transmits specific information to control devices other than the k-th control device among the first control device to the m-th control device. The specific information includes voltage values of a plurality of unit converters included in a k-th cell set in each of a first arm to a third arm. From each control device other than the k-th control device among the first control device to the m-th control device, the k-th control device receives specific information including the voltage values of the plurality of unit converters. The k-th control device calculates a phase representative value of the voltage values of the plurality of unit converters included in each of the first arm to the third arm.

Abstract: A power conversion device includes: a first control unit and a second control unit that output a first control signal and a second control signal, respectively; a gate circuit that causes a control signal selected from the first control signal and the second control signal to pass through the gate circuit; and a drive circuit that drives a main circuit based on the control signal that passes through the gate circuit. When the second control signal is selected in the state where the first control signal passes through the gate circuit, the gate circuit interrupts the first control signal and causes the second control signal to pass through the gate circuit as an absolute value of an instantaneous value of an AC current decreases below a threshold current.

Abstract: In the present power conversion device, when a fault occurs in a power system (1) and DC voltage (VDC) of a capacitor (15) included in a unit converter (5) exceeds a protection level (VH), the operation of an inverter (10) is stopped. When the DC voltage (VDC) decreases to a recovery level (V1) or lower, DC voltage control of the inverter (10) is resumed to quickly decrease the DC voltage (VDC). When the DC voltage (VDC) decreases to a recovery level (V2) or lower, reactive power control of the inverter (10) is resumed. Thus, even when a fault occurs in the power system (1), the operation of the inverter (10) can be quickly resumed.

Abstract: A control device generates a voltage command value for controlling a current flowing between a three-phase AC power supply and a power converter such that a full voltage representative value representing voltage values of all power storage devices agrees with a DC voltage command value. The control device generates a zero-phase voltage command value for controlling a circulating current flowing in a delta connection such that the voltage values of the power storage devices are balanced among first to third arms. The control device combines the voltage command value and the zero-phase current command value to generate an output voltage command value for controlling an output voltage of each unit converter. The control device removes a control amount of the full voltage representative value from a computation of the zero-phase voltage command value to cause output current control and circulating current control not to interfere with each other.

Abstract: In the present power conversion device, when a fault occurs in a power system (1) and DC voltage (VDC) of a capacitor (15) included in a unit converter (5) exceeds a protection level (VH), the operation of an inverter (10) is stopped. When the DC voltage (VDC) decreases to a recovery level (V1) or lower, DC voltage control of the inverter (10) is resumed to quickly decrease the DC voltage (VDC). When the DC voltage (VDC) decreases to a recovery level (V2) or lower, reactive power control of the inverter (10) is resumed. Thus, even when a fault occurs in the power system (1), the operation of the inverter (10) can be quickly resumed.

Abstract: A power converter is electrically connected with an AC power supply via a switch, and is configured with a plurality of unit converters (5) connected in series. A drive circuit (40, 42) drives a plurality of switching elements (11 to 14) of a main circuit (30). An interface circuit (48) outputs a detection value of a voltage sensor (46) to a control device (4). If a bypass switch (7) is turned off when the power converter is activated, each of the plurality of unit converters (5) charges a capacitor (15) using power supplied from the AC power supply. When the power converter is activated, a power supply (50) supplies a power supply voltage to the voltage sensor (46) and the interface circuit (48), prior to the drive circuit (40, 42). The control device (4) turns off the switch when the detection value of the voltage sensor (46) of at least one of the plurality of unit converters (5) is more than or equal to a predetermined value.

Abstract: A control device generates a voltage command value for controlling a current flowing between a three-phase AC power supply and a power converter such that a full voltage representative value representing voltage values of all power storage devices agrees with a DC voltage command value. The control device generates a zero-phase voltage command value for controlling a circulating current flowing in a delta connection such that the voltage values of the power storage devices are balanced among first to third arms. The control device combines the voltage command value and the zero-phase current command value to generate an output voltage command value for controlling an output voltage of each unit converter. The control device removes a control amount of the full voltage representative value from a computation of the zero-phase voltage command value to cause output current control and circulating current control not to interfere with each other.

Abstract: A power converter is electrically connected with an AC power supply via a switch, and is configured with a plurality of unit converters (5) connected in series. A drive circuit (40, 42) drives a plurality of switching elements (11 to 14) of a main circuit (30). An interface circuit (48) outputs a detection value of a voltage sensor (46) to a control device (4). If a bypass switch (7) is turned off when the power converter is activated, each of the plurality of unit converters (5) charges a capacitor (15) using power supplied from the AC power supply. When the power converter is activated, a power supply (50) supplies a power supply voltage to the voltage sensor (46) and the interface circuit (48), prior to the drive circuit (40, 42). The control device (4) turns off the switch when the detection value of the voltage sensor (46) of at least one of the plurality of unit converters (5) is more than or equal to a predetermined value.

Abstract: A thyristor starting device includes: a converter which converts AC power supplied from an AC power source into DC power; a DC reactor which smooths a DC current; an inverter which converts the DC power provided from the converter into AC power, and supplies the AC power to a synchronous machine; a gate pulse generation circuit which generates a gate pulse to be provided to thyristors of the converter and the inverter; a control unit which sets a phase control angle of the gate pulse to be provided to the thyristors of the converter, by controlling a current of the converter such that the DC current flowing into the DC reactor matches a current command value; and an abnormality detection unit which compares a detection value of the DC current with the current command value, and determines an abnormality in the gate pulse based on a comparison result.

Abstract: A thyristor starting device includes: a converter which converts AC power supplied from an AC power source into DC power; a DC reactor which smooths a DC current; an inverter which converts the DC power provided from the converter into AC power, and supplies the AC power to a synchronous machine; a gate pulse generation circuit which generates a gate pulse to be provided to thyristors of the converter and the inverter; a control unit which sets a phase control angle of the gate pulse to be provided to the thyristors of the converter, by controlling a current of the converter such that the DC current flowing into the DC reactor matches a current command value; and an abnormality detection unit which compares a detection value of the DC current with the current command value, and determines an abnormality in the gate pulse based on a comparison result.

Abstract: A power conversion device includes a converter, a DC reactor, and an inverter. A control unit controls the converter according to a sum of a feedback control amount and a feedforward control amount, the feedback control amount being calculated based on a deviation between a current command value and the DC current flowing into the DC reactor, the feedforward control amount being set in accordance with a DC voltage provided from the converter through the DC reactor. When an output frequency of the inverter is in a first region, the control unit reduces a control gain used to calculate the feedforward control amount, as compared to when the output frequency is in a second region having a frequency lower than that of the first region.