Abstract: A current suppression control unit calculates correction terms of reference voltage command values for operating a power converter as a voltage source. The correction terms are calculated to compensate for respective current deviations of output currents transformed on two axes, with respect to current command values on a two-axis rotating coordinate system for suppressing an output current of the power converter to less than or equal to a control upper limit value. A proportional control unit has proportional elements to reflect the current deviations in the correction terms within the same axes of the two axes. A decoupling control unit has integral elements to reflect the current deviations in the correction terms between the different two axes.

Abstract: A power conversion device includes a power converter connected to a power storage element, and a control device. The control device includes a generator simulating unit to generate a voltage command value, and a signal generating unit to generate a control signal for the power converter based on the voltage command value. The generator simulating unit includes a first characteristics simulating unit to generate a first command value by simulating characteristics of a first synchronous generator, a second characteristics simulating unit to generate a second command value by simulating characteristics of a second synchronous generator different from the characteristics of the first synchronous generator, an adder to perform addition of the first command value and the second command value, and a voltage command generating unit to generate the voltage command value, based on an addition result of the first command value and the second command value.

Abstract: A power conversion device includes a voltage-type power converter and a current-type power converter each of which performs power conversion between AC and DC, and a controlling circuitry, and power is transmitted/received between AC sides via a DC circuit. In first starting control for starting the voltage-type power converter and the current-type power converter, the controlling circuitry controls a semiconductor element of at least one of the voltage-type power converter and the current-type power converter, to adjust DC voltage at DC terminals of the voltage-type converter to a set first voltage value, thereby controlling current flowing through the DC circuit to be first current not greater than a rated current value of the semiconductor elements.

Abstract: A control device includes a generator simulating unit to generate a phase of output voltage of a power converter by simulating characteristics of a synchronous generator, a first voltage command generating unit to generate a first voltage command value of output voltage of the power converter so that an AC voltage of a power grid attains a target voltage, a setting unit to set an overcurrent level, and a second command generating unit to generate a second voltage command value by limiting the first voltage command value based on the overcurrent level. The control device further includes a signal generating unit to generate a control signal for the power converter, based on the phase generated by the generator simulating unit and the second voltage command value.

Abstract: A power conversion device includes a power converter and a control device. The power converter converts a DC power output from a power storage element into an AC power. The control device includes a phase synchronizing unit to estimate a reference phase of an output voltage of the power converter synchronized with a phase of an AC voltage at an interconnection point, a characteristics simulating unit to generate an active power command value based on a phase difference between a reference phase and the phase of the AC voltage at the interconnection point, a DC voltage command generating unit to generate a DC voltage command value, a voltage command generating unit to generate an AC voltage command value so that an output current of the power converter becomes less than a threshold, and a signal generating unit to generate a control signal based on the AC voltage command value.

Abstract: A power conversion unit includes a plurality of arms each having a plurality of converter cells connected to each other in cascade. A converter control unit that controls the power conversion unit includes a voltage command value computing unit to compute an output voltage command value for each arm, and a gate signal generating unit to generate an on/off control signal of each switching element of each converter cell in accordance with the output voltage command value. A voltage command value computing unit is configured to generate the output voltage command value with compensation for an AC vibration component, extracted for each arm, of stored energy of power storage elements of a plurality of converter cells included in the 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 voltage-type power converter and a current-type power converter each of which performs power conversion between AC and DC, and a controlling circuitry, and power is transmitted/received between AC sides via a DC circuit. In first starting control for starting the voltage-type power converter and the current-type power converter, the controlling circuitry controls a semiconductor element of at least one of the voltage-type power converter and the current-type power converter, to adjust DC voltage at DC terminals of the voltage-type converter to a set first voltage value, thereby controlling current flowing through the DC circuit to be first current not greater than a rated current value of the semiconductor elements.

Abstract: A power conversion device which is connected between an electric generation grid and a demand area grid and performs power conversion includes: a power converter which is connected to an electric generation grid and which converts AC power received from the electric generation grid to DC power and transmits the DC power via DC bus; and a control device for controlling the power converter. The control device includes a detection unit for detecting DC current of the DC bus, and a protection control unit for performing protection control for suppressing an amount of power received from the electric generation grid, on the basis of variation in the DC current, thereby continuing operation in the case of disturbance in the demand area grid.

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 DC power transmission system interconnects a plurality of AC systems via a DC line. A plurality of power conversion devices are connected between the plurality of AC systems and the DC line. One of the plurality of power conversion devices controls the voltage on the DC line, while the remaining power conversion device controls a current input and output to and from the DC line. In a restart which resumes power conversion from a stopped state for controlling a DC current on the DC line, the power conversion device performing current control monitors the voltage on the DC line and starts a restart operation without transmitting or receiving information to or from the other power conversion device.

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 DC power transmission system interconnects a plurality of AC systems via a DC line. A plurality of power conversion devices are connected between the plurality of AC systems and the DC line. One of the plurality of power conversion devices controls the voltage on the DC line, while the remaining power conversion device controls a current input and output to and from the DC line. In a restart which resumes power conversion from a stopped state for controlling a DC current on the DC line, the power conversion device performing current control monitors the voltage on the DC line and starts a restart operation without transmitting or receiving information to or from the other power conversion device.

Abstract: Since a power converter including a modular multilevel converter uses a large number of cells each combining a plurality of switching elements and a DC capacitor, there is a problem of conduction loss due to the switching elements. The conduction loss is reduced by connecting a bypass circuit between terminals of each of the cells, controlling to open and close the switching element, and controlling to short-circuit the bypass circuit connected to the cell controlled to output zero voltage.

Abstract: The present invention is provided with a power converter and a control device for controlling the power converter, wherein each of the positive arm and the negative arm is comprised one converter cell or a plurality of converter cells connected in series, each converter cell being comprised: a series unit in which a plurality of switching elements are connected in series to each other; and a DC capacitor connected in parallel to the series unit, and the control device includes a DC voltage command value calculation unit which calculates a voltage command value for outputting, during a DC short circuit fault, AC voltage similar to that in a steady state to the AC terminal of the power converter, and for outputting, to the DC terminal of the power converter, DC voltage that allows the protection relay in the DC line to operate.

Abstract: A power conversion device which is connected between an electric generation grid and a demand area grid and performs power conversion includes: a power converter which is connected to an electric generation grid and which converts AC power received from the electric generation grid to DC power and transmits the DC power via DC bus; and a control device for controlling the power converter. The control device includes a detection unit for detecting DC current of the DC bus, and a protection control unit for performing protection control for suppressing an amount of power received from the electric generation grid, on the basis of variation in the DC current, thereby continuing operation in the case of disturbance in the demand area grid.

Abstract: When switching operations of converter cells are stopped due to temporary voltage reduction in an AC system, a voltage determination unit performs determination regarding a voltage of each DC capacitor after a predetermined period has passed, and a charge control unit transmits a charging gate signal, via a gate control unit, to select a converter cell at a voltage level at which a self-feeding circuit of the converter cell is operable. Thus, a DC capacitor of a converter cell whose voltage is lower than the voltage level at which a self-feeding circuit is operable is charged, thereby enabling switching operations of all the converter cells.

Abstract: Since a power converter including a modular multilevel converter uses a large number of cells each combining a plurality of switching elements and a DC capacitor, there is a problem of conduction loss due to the switching elements. The conduction loss is reduced by connecting a bypass circuit between terminals of each of the cells, controlling to open and close the switching element, and controlling to short-circuit the bypass circuit connected to the cell controlled to output zero voltage.

Abstract: The present invention is provided with a power converter and a control device for controlling the power converter, wherein each of the positive arm and the negative arm is comprised one converter cell or a plurality of converter cells connected in series, each converter cell being comprised: a series unit in which a plurality of switching elements are connected in series to each other; and a DC capacitor connected in parallel to the series unit, and the control device includes a DC voltage command value calculation unit which calculates a voltage command value for outputting, during a DC short circuit fault, AC voltage similar to that in a steady state to the AC terminal of the power converter, and for outputting, to the DC terminal of the power converter, DC voltage that allows the protection relay in the DC line to operate.

Abstract: A power conversion device includes: a positive arm and a negative arm each of which is formed by connecting a plurality of converter cells in series, the converter cells each being composed of a plurality of semiconductor switching elements and a DC capacitor; and a control circuit. An arm balance control unit in the control circuit calculates a first voltage adjustment value for balancing voltage of the DC capacitors in the positive arm and voltage of the DC capacitors in the negative arm. The control circuit adjusts an AC control command using the first voltage adjustment value, thereby calculating an AC voltage command for AC voltage to be outputted to an AC line for each phase.