Mitsubishi Electric Corporation

Tdk Corporation

Keisuke Ishida

Makoto Endo

Koichi Yamaguchi

Takayuki Fujisawa

Shimpei Tanabe

Noriyuki Imada

Masahiro Hario

Yasunori Ido

In a multi-terminal DC power transmission system, a common control device is connected to a plurality of individual protective devices via a first communication network. Each of the individual protective devices is configured, when detecting change in current or voltage in a corresponding protection zone, to output a fault signal to the common control device via the first communication network and open the corresponding DC circuit breaker such that the corresponding protection zone is disconnected from the multi-terminal DC power grid and deenergized. The common control device estimates a fault occurrence zone where a fault occurs among a plurality of protection zones, based on a plurality of received fault signals. The common control device requests an individual protective device corresponding to a deenergized protection zone of the protection zones excluding the fault occurrence zone to reclose the DC circuit breaker such that the deenergized protection zone is restored.

Multi-terminal DC power transmission system, common control device thereof, and fault recovery method for multi-terminal DC power transmission system

A power conversion device converts power between a direct-current (DC) circuit and an alternating-current (AC) circuit. The power conversion device includes a power converter circuit which includes a plurality of unit converters connected in series, and a controller. The unit converter includes one or more switching elements and a capacitor. The controller transmits, to the unit converter through a first transmission medium, information on a switching command for the unit converter. The unit converter transmits, to the controller through a second transmission medium, information on at least one condition of the unit converter. The first transmission medium is an optical fiber, and the second transmission medium is a wireless communication channel.

Power conversion device

A power system includes: a self-commutated power converter including a first arm and a second arm, each including switching elements; a first circuit breaker configured to interrupt a current flowing through a power transmission line provided between a first bus and a second bus; a first circuit breaker control unit configured to control the first circuit breaker; a converter control unit configured to stop the switching elements based on a first arm current value and a second arm current value; and a setting unit configured to set a voltage value of an AC voltage output from the power converter such that when a fault occurs in the power transmission line, the first circuit breaker is opened while the switching elements are not stopped. The converter control unit is configured to operate the switching elements such that an AC voltage with the set voltage value is output.

Power control system and control device for restoring AC system from power failure

A power control system includes: a first AC/DC converter; a second AC/DC converter; a first switch connected between a first transmission line of a first power system having a first system frequency and the first AC/DC converter; a second switch connected between the first transmission line and the second AC/DC converter; a third switch connected between a second transmission line of a second power system having a second system frequency and the first AC/DC converter; a fourth switch connected between the second transmission line and the second AC/DC converter; a fifth switch connected between the first AC/DC converter and the second AC/DC converter; and a control device. When the first and second AC/DC converters are caused to operate as AC/DC converters in a BTB (Back to Back) method, the control device controls at least the fifth switch to be in a closed state.

Power control system and control device

A power conversion device in one embodiment includes power conversion circuitry having a plurality of converter cells connected in series to each other. Each converter cell includes an energy storage device and is configured to be capable of discharging stored energy. A control device is configured to generate a control command for controlling operation of each converter cell. A protection device is configured to generate a protection command for instructing whether to cause each converter cell to operate based on the control command or to stop operation of each converter cell regardless of the control command. A repeating device is configured to generate a control-and-protection command that is a combination of control information based on the control command and protection information based on the protection command, and output the generated control-and-protection command to each converter cell.

A laminated ceramic electronic component provided with a component main body formed by alternatively laminating multiple dielectric ceramic layers and multiple internal electrode layers, and external electrodes disposed on the end faces where the internal electrode layers of the component main body are exposed, wherein at least a part of the multiple internal electrode layers exposed on the end faces of the component main body are provided with end-face electrode portions that connect the adjacent internal electrode layers, the connecting portions are present between the end-face electrode portions and the dielectric ceramic layers that contact with the end-face electrode portions, and the external electrodes are disposed so that the end-face electrode portions are covered.

Laminated ceramic electronic component

A laminated ceramic electronic component with a cuboid-shaped element main body having a first main face and a second main face elongating along the length direction and the width direction, a first side face and a second side face elongating along the length direction and the height direction, and a first end face and a second end face elongating along the width direction and the height direction; and a pair of internal electrode layers opposite to each other in the height direction inside the element main body with a dielectric layer interposed therebetween in such a manner that they are exposed at the first end face or the second end face, wherein the thickness of the dielectric layer becomes larger from central portion to the first side face and the second side face.

A laminate-type ceramic electric component such as laminated ceramic capacitor which has excellent mechanical strength and also has thermal shock resistance at the same time is provided. A laminate-type ceramic electronic component includes an inner layer part, in which dielectric layers including ABO(which represents a perovskite crystal in which A contains at least Ba and B contains at least Ti) as a main component and internal electrode layers are alternately laminated; and a pair of outer layer parts which sandwich the inner layer part, wherein the outer layer parts include a continuous film containing a Ba&#x2014;Si&#x2014;Ti&#x2014;O based crystal phase.

Laminate-type ceramic electronic component

The present invention aims to suppress the cracks and delamination to improve the bending strength of multilayer ceramic electronic component with internal electrode layers wherein the thickness of the internal electrode layer is 0.5 &#x3bc;m or less. The multilayer ceramic electronic component is a laminated body having internal electrode layers and dielectric ceramic layers which are laminated alternately. The internal electrode layers have electrode discontinuity portion. In a part of the electrode discontinuity portion, a dielectric ceramic particle bigger than the thickness of the dielectric ceramic layer is contained when the cross section is observed from the direction perpendicular to the laminating plane of the laminated body. The dielectric ceramic particles have the same crystal structure with the dielectric ceramic particles contained in the dielectric ceramic layers, and contact with at least one internal electrode layers which are opposite to each other with dielectric ceramic layers sandwiched therebetween.

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Tokyo, Japan

Keisuke Ishida