Abstract: A control device for an active filter connected in parallel with a load at an installation point with respect to an AC power supply provided in a power system includes a harmonic voltage detector to detect an m-order harmonic voltage (m is an integer not less than two) included in a voltage of the installation point, a phase corrector to correct a phase of the detected m-order harmonic voltage in accordance with whether an m-order harmonic impedance when an AC power supply side is seen from the installation point is capacitive or inductive, a command value generator to generate a first compensation command value for compensating for the m-order harmonic voltage included in the voltage of the installation point based on the m-order harmonic voltage after the correction, and an output controller to control an output of the active filter based on a first compensation command value.

Abstract: A control device for an active filter connected in parallel with a load at an installation point with respect to an AC power supply provided in a power system includes a harmonic voltage detector to detect an m-order harmonic voltage (m is an integer not less than two) included in a voltage of the installation point, a phase corrector to correct a phase of the detected m-order harmonic voltage in accordance with whether an m-order harmonic impedance when an AC power supply side is seen from the installation point is capacitive or inductive, a command value generator to generate a first compensation command value for compensating for the m-order harmonic voltage included in the voltage of the installation point based on the m-order harmonic voltage after the correction, and an output controller to control an output of the active filter based on a first compensation command value.

Abstract: In a reactive power compensation device, a control unit controls a magnitude of reactive power to be output by a reactive power output unit, based on a detected system voltage and one or more control parameters in a first operation mode. In a second operation mode, the control unit changes the magnitude of the reactive power to be output by the reactive power output unit to a power system in an output change period, calculates system impedances of the power system at a plurality of detection time points within the output change period, based on change amounts of the system voltage detected at the plurality of detection time points and corresponding change amounts of the reactive power, and, when a variation in the calculated system impedances is within an acceptable range, adjusts the one or more control parameters, based on the calculated system impedances.

Abstract: Three-phase thyristor switched capacitors are delta-connected to three-phase AC buses. Each thyristor switched capacitor includes a reactor, a capacitor, and a thyristor switch that are electrically connected in series. The thyristor switches of the three phases are arranged so that the terminal-to-terminal distance between respective thyristor switches of respective phases are not uniform. The three-phase thyristor switched capacitors are configured so that the thyristor switched capacitors of two of the three phases having a shortest terminal-to-terminal distance therebetween are opposite to each other in terms of connection order in which the thyristor switch and the capacitor are electrically connected along a loop path made up of the delta-connected thyristor switched capacitors.

Abstract: Three-phase TSCs are delta-connected to three-phase AC buses. Each TSC includes a reactor, a capacitor, and a thyristor switch that are electrically connected in series. The thyristor switches of the three phases are arranged so that the terminal-to-terminal distance between respective thyristor switches of respective phases are not uniform. The three-phase TSCs are configured so that the TSCs of two of the three phases having a shortest terminal-to-terminal distance therebetween are opposite to each other in terms of connection order in which the thyristor switch and the capacitor are electrically connected along a loop path made up of the delta-connected TSCs.

Abstract: A capacitor bank unit includes three capacitor banks that have respective capacitances that are multiples of a basic capacitance in accordance with a number sequence of the n-th power of 2. One of the capacitor banks has the basic capacitance, remaining two of the capacitor banks includes two subbanks each. The capacitance of a subbank is set to a capacitance that is a multiple of the basic capacitance in accordance with a number sequence of the m-th power of 2. When any one of the capacitor banks fails, each of capacitor banks following the failed capacitor bank substitutes for a capacitor bank located immediately before itself.

Abstract: An objective is to prevent excessive temperature decrease of cooling water and to reduce energy loss by a heater. A water-cooled electrical apparatus includes an electrical device 2 placed indoors, a pump 3 for circulating cooling water for cooling the electrical device, a cooler 5, placed outdoors, for cooling the cooling water, a heater 6 for heating the cooling water, and a main pipe 4 forming a closed loop so that the cooling water circulates through the electrical device, the pump, the cooler, and the heater. The water-cooled electrical apparatus further includes a bypass pipe 11 bypassing between bifurcations 9 and 10, provided at inlet and outlet sides of the cooler, for flow-dividing the cooling water, and at least one of a first flow amount control valve 7 provided along the main pipe between the bifurcations, and a second flow amount control valve 12 provided along the bypass pipe.

Abstract: A converter controllable in regenerative running mode, which is a power converting apparatus capable of suppressing harmonics without increasing the size of a reactor, and reducing power loss and electromagnetic noise. A power converter is configured by directly connecting AC sides of single-phase sub-converters having a DC voltage lower than a DC voltage of a 3-phase main converter to AC input lines of individual phases thereof in series. The main converter is driven by one gate pulse per half recurring cycle and a voltage produced by each sub-converter at AC terminals thereof is controlled to match a difference between an AC power supply voltage and a voltage produced by the main converter at AC terminals thereof, whereby phase voltages of the power converter are generated as the sums of phase voltages of the individual converters.

Abstract: A power conversion device including sub-inverters, each connected in series with respective phase of a three-phase main inverter including a smoothing capacitor, which is fed from a power supply via a converter, as a DC input thereof, and feeds power to a load using the sum of outputs of the inverters. A manipulative quantity is determined so that the DC voltage at each of smoothing capacitors which is an input of each of the sub-inverters will follow a command value. The manipulative quantity is added to an output voltage command for the three-phase main inverter, and is subtracted from an output voltage command for the sub-inverters. Thus, power is shifted from the three-phase main inverter to the smoothing capacitors of the sub-inverters.

Abstract: A capacitor bank unit includes three capacitor banks that have respective capacitances that are multiples of a basic capacitance in accordance with a number sequence of the n-th power of 2. One of the capacitor banks has the basic capacitance, remaining two of the capacitor banks includes two subbanks each. The capacitance of a subbank is set to a capacitance that is a multiple of the basic capacitance in accordance with a number sequence of the m-th power of 2. When any one of the capacitor banks fails, each of capacitor banks following the failed capacitor bank substitutes for a capacitor bank located immediately before itself.

Abstract: A converter controllable in regenerative running mode, which is a power converting apparatus capable of suppressing harmonics without increasing the size of a reactor, and reducing power loss and electromagnetic noise. A power converter is configured by directly connecting AC sides of single-phase sub-converters having a DC voltage lower than a DC voltage of a 3-phase main converter to AC input lines of individual phases thereof in series. The main converter is driven by one gate pulse per half recurring cycle and a voltage produced by each sub-converter at AC terminals thereof is controlled to match a difference between an AC power supply voltage and a voltage produced by the main converter at AC terminals thereof, whereby phase voltages of the power converter are generated as the sums of phase voltages of the individual converters.

Abstract: A power conversion device including sub-inverters, each connected in series with respective phase of a three-phase main inverter including a smoothing capacitor, which is fed from a power supply via a converter, as a DC input thereof, and feeds power to a load using the sum of outputs of the inverters. A manipulative quantity is determined so that the DC voltage at each of smoothing capacitors which is an input of each of the sub-inverters will follow a command value. The manipulative quantity is added to an output voltage command for the three-phase main inverter, and is subtracted from an output voltage command for the sub-inverters. Thus, power is shifted from the three-phase main inverter to the smoothing capacitors of the sub-inverters.

Abstract: A power conversion apparatus connected to an AC voltage system, including current control circuits provides individual feedback control of an active current and a reactive current. The active current control circuit changes control gain of the active current according to a detected active current value or a deviation of the detected active current value from an active current command value.

Abstract: There is a power conversion apparatus connected to an AC voltage system 5, comprising current control circuits 11, 12 capable of individually performing feedback control of an active current and a reactive current, and the active current control circuit 11 is constructed so as to change a control gain of the active current according to a detected active current value or a deviation of a detected active current value from an active current command value.

Abstract: A power conversion equipment capable of dealing with an imbalance fault by changing characteristics of a filter for extracting negative-phase-sequence voltage in a steady state and at the time of a system fault, and a control device for the conversion equipment. The control device for power conversion equipments includes a negative-phase-sequence component extractor including first and second negative-phase-sequence component extraction filters having different extracting capabilities, and for extracting a negative-phase-sequence component from the two phase voltage using the first negative-phase-sequence component extraction filter in a steady state and extracting a negative-phase-sequence component from the two phase voltage using the second negative-phase-sequence component extraction filter in a transient state.