Abstract: The present invention relates to a line start synchronous reluctance motor and a rotor thereof. To this end, the present invention provides a line start synchronous reluctance motor including: a rotor; a plurality of conductor bars disposed on a side of an outer circumferential portion of the rotor; and flux barriers formed at an inner side of the rotor so as to be close to the conductor bars, wherein the flux barriers, which are formed in separate regions of a body of the rotor that are arranged to have opposite polarities, are formed to be asymmetrical to each other. Therefore, the present invention improves characteristics of the motor through the asymmetrical flux-barrier structure without changing the number of conductor bars, thereby allowing the initial starting of the motor to be smoothly performed, which is advantageous in terms of torque ripple characteristics and die casting.

Abstract: The present invention relates to an apparatus for cooling a power device of a power conditioning system. To this end, the present invention comprises: a power device; an evaporator butted to the power device; and a modularized condenser which is connected with the evaporator, placed on the power device, and equipped on the upper side of the power conditioning system. Accordingly, the present invention may easily secure a space, make it easy to install, and increase heat emission performance of the condenser so as to keep the power device at a low temperature, thereby enabling the system to be stably operated over a long period of time.

Abstract: An MMC converter linked to a HVDC system and a sub-module constituting the MMC converter are proposed. The sub-module includes: first and second power semiconductor switches connected in series in the same direction, each including a semiconductor switch and a diode connected in anti-parallel to the semiconductor switch; a capacitor connected in parallel to the first and second power semiconductor switches connected together in series; a first terminal connected to a first node between the first and second power semiconductor switches; a second terminal connected to a second node between the second power semiconductor switch and the capacitor; third and fourth power semiconductor switches connected in series in opposite directions between the first and second terminals, each including a semiconductor switch and a diode connected in anti-parallel to the semiconductor switch; and a third terminal connected to a third node between the third and fourth power semiconductor switches.

Abstract: A method of removing a direct current component at an output terminal of an MMC converter according to the present invention includes a detection step of individually detecting charging voltages charged in capacitors of a plurality of sub-modules connected in series to each other in the MMC converter; outputting an average value of the individually detected charging voltages; delaying the outputted average value by a predetermined phase to output a phase-delayed average value; outputting the average value and the phase-delayed average value as a q-axis component voltage by using a predetermined dq conversion unit; calculating an error between the q-axis component voltage and a three-phase average voltage for the q-axis component voltage; and outputting, through a pre-determined first PI control unit, an offset voltage for reducing the error.

Abstract: An MMC converter linked to a HVDC system and a sub-module are proposed. The sub-module includes: first and second power semiconductor switches serially connected in the same direction, each including a semiconductor switch and a diode connected in anti-parallel to the semiconductor switch; a capacitor parallelly connected to the first and second power semiconductor switches serially connected; a first terminal connected to a first node between the first and second power semiconductor switches; a second terminal connected to a second node between the second power semiconductor switch and the capacitor; a third power semiconductor switch of which a side is connected to the second node, the third power semiconductor switch including a semiconductor switch and a diode connected in anti-parallel to the semiconductor switch; and a third terminal connected to a terminal of an AC grid system and connected to the other side of the third power semiconductor switch.

Abstract: Provided is a microgrid system having: a plurality of distributed power sources; a plurality of distributed loads; and lines for connecting the distributed power sources and the distributed loads, the microgrid system including: an ESS for storing power supplied from all or a portion of the distributed power sources and supplying the stored power to all or a portion of the distributed loads; an ESS PCS including an interruption means for converting the power stored in the ESS into AC power suitable for the microgrid and supplying the AC power to the microgrid in order to block connection to the microgrid in an abnormal state; and a monitoring/control device for gradually increasing a voltage output from the ESS PCS and performing processing for the failure when a failure is detected in the microgrid.

Abstract: A modular multilevel converter (MMC) includes multiple converter arms, each converter arm having: N submodules connected to each other in series, N being an integer equal to or greater than 2; and a circuit opening unit connected to the N submodules in series to open a circuit of the converter arm, wherein the N submodules has n submodules including full-bridge circuits and N?n submodules including half-bridge circuits, n being less than N.

Abstract: Provided is an apparatus and method for controlling a circuit breaker for a static synchronous compensator (STATCOM) such that the circuit breaker installed in a branch line for the STATCOM is operated according to the current control characteristics of the STATCOM, the apparatus including: a transformer protector for detecting the differential current between primary current and secondary current of a transformer connected in series to the circuit breaker in the branch line, and controlling the opening/closing of the circuit breaker; and a STATCOM controller for controlling an operation of the STATCOM, wherein the STATCOM controller outputs, to the transformer protector, an opening suspension signal for suspending the opening of the circuit breaker when overvoltage occurring in the STATCOM is detected, and the transformer protector suspends output of a circuit breaker opening signal to the circuit breaker according to the received opening suspension signal.

Abstract: Provided is a capacitor discharge device that quickly and safely discharges a capacitor charged with energy inside a sub-module of an MMC converter, the device including: a capacitor storing a DC voltage inside a sub-module of an MMC converter; a power supply unit supplying operating power required in the submodule by using the voltage stored in the capacitor; a first resistor connected in parallel to the capacitor; a second resistor having a lower resistance value and a larger heat capacity than the first resistor so as to rapidly discharge the capacitor storing the voltage; a first switching contact connecting and disconnecting the capacitor and the second resistor; a switching unit operating switching of the first switching contact by the operating power; a second switching contact connecting and disconnecting the power supply unit and the switching unit; and a control unit operating switching of the second switching contact.

Abstract: Provided is a hybrid control device for a static synchronous compensator (STATCOM), the device including: a first arithmetic operation unit calculating the deviation between a reference voltage desired to be controlled by the STATCOM and output voltage to be output so as to output the same; a proportional integral (PI) controller performing PI control on the deviation output from the first arithmetic operation unit within a range between a new inductive reactive current maximum value and a new capacitive reactive current maximum value, so as to output a reactive current output value; and a second arithmetic operation unit adding the preset reactive current set value to the reactive current output value output from the PI control unit so as to output a reactive current reference value.

Abstract: Provided is a battery lifetime estimating method including steps of: fully charging a battery according to a predetermined charging condition; partially discharging the fully charged battery according to a predetermined discharging condition; acquiring voltage information at a plurality of predetermined measurement time points while performing the partially discharging; and estimating a remaining capacity of the battery by using the acquired voltage information. Herein, the step of estimating the remaining capacity of the battery includes steps of: calculating the capacity of the battery in one cycle of fully charging/discharging in which the measurement is performed from the measured voltage drop amounts; and estimating the remaining lifetime of the battery by applying a statistical technique to the capacity of the battery calculated with respect to a plurality of cycles of fully charging/discharging.

Abstract: Provided is a transformer having a noise reducing means. The transformer includes: an iron core (P), which is formed by stacking a plurality of steel sheets, and has stepped parts (S) formed at a portion thereof with different widths; and the noise reducing means provided at the stepped parts (S) so as to increase coupling force among the plurality of steel sheets. The noise reducing means includes: pressing bars (30) mounted on the stepped parts (S) of the iron core (P), and having plane-shaped horizontal pressing surfaces (31) in the direction in which the steel sheets are stacked; and a binding (90) for surrounding the outer surface of the iron core (P) including the pressing bars (30), so as to press the pressing bars (30) in the stacking direction of the steel sheets.

Abstract: The present invention relates to a dual controller system for analyzing a control signal received from two dual controllers, both of which operate in an active state, to check whether an error occurs in the controllers and to perform operation with a controller in a normal state. A dual controller system according to the present invention includes a plurality of lower-layer modules performing respective functions, and first and second controllers for controlling each of the plurality of lower-layer modules, wherein the first and second controllers transmit control signals to the plurality of lower-layer modules, and the lower-layer modules determine whether an error occurs in the two received control signals, remove an erroneous control signal and perform a function according to a normal control signal.

Abstract: An actuator for a high-speed switch is proposed. The actuator can include a frame having multiple mounting plates and columns. The mounting plates have parts installed thereon or movably supported thereby. The columns maintain the space between the mounting plates. A permanent magnet is installed on one of the mounting plates so as to face the second driving plate, and an elastic member is installed on the mounting plate that faces the mounting plate having the permanent magnet installed thereon, so as to provide force for the movement of the second driving plate.

Abstract: A modular multilevel converter (MMC) converter including an auxiliary sub-module provided between an upper converter arm and a lower converter arm of the MMC converter is provided. An MMC converter includes an auxiliary sub-module including: an energy storage unit storing a DC voltage in the sub-module; a first semiconductor switch connected to the energy storage unit; a second semiconductor switch connected to the first semiconductor switch; a third semiconductor switch connected to the second semiconductor switch; and a switching controller turning ON/OFF the first to third semiconductor switches, wherein a mid-point between the first and second semiconductor switches is connected to the sub-module of the upper converter arm, a mid-point between the second and third semiconductor switches is connected to a load connection terminal, and a mid-point between the third semiconductor switch and the energy storage unit is connected to the sub-module of the lower converter arm.

Abstract: Provided is a battery managing device that stores surplus power provided from a system via a power managing device, and controls the charging and discharging of a battery formed of multiple battery modules which supply stored power to the system. The battery managing device includes: a switch block that connects the multiple battery modules to the power managing device; a charging circuit that charges the battery by means of the power input from the power managing device; a smoothing circuit that discharges or charges the battery according to the real-time power deficit/surplus state of the system; and a control circuit that controls the operation of the switching block, the charging circuit, and the smoothing circuit.

Abstract: The present invention relates to a bus conductor connection structure for electric field relaxation. The bus conductor connection structure for electric field relaxation includes: an enclosure filled with an inert gas; spacers coupled to two side end portions of the enclosure in a facing contact manner and having connection conductors; conductors provided with predetermined intervals being maintained inside the enclosure; and coupling portions formed in end portions of the conductors, wherein the coupling portion is coupled to the connection conductor in a close contact manner with bolts. Accordingly, the bus conductor connection structure for electric field relaxation is allowed to simply fixing conductors and assembling bolts of a gas insulated bus and to reduce a size of the bus by shortening an insulation distance between the bus and the ground by using a shape and arrangement for electric field relaxation.

Abstract: Provided is a DC breaker that can block a fault current generated in a direct current line, by using a unidirectional semiconductor switch device. The DC breaker includes: a mechanical switch that is connected between first and second direct current lines; a first unidirectional semiconductor switch device that transfers a resonant current to the first direct current line when the fault current is generated, so that a current of the first direct current line becomes zero; an LC resonant circuit that is charged by receiving a steady state current of the first direct current line, and generates the resonant current to the first unidirectional semiconductor switch device when the fault current is generated; and a second unidirectional semiconductor switch device that enables a capacitor of the LC resonant circuit to be charged with the steady state current of the first direct current line.

Abstract: The present invention relates to an MMC converter system which can quickly cut off fault current by installing a plurality of disconnecting switch units on a line connected between two MMC converter devices. The MMC converter system comprises: a first MMC converter device including a plurality of serially connected sub modules; a second MMC converter device including a plurality of serially connected sub modules; a first disconnecting switch unit installed on a line between the first and second MMC converter devices; and a second disconnecting switch unit connected in series to the first disconnecting switch unit on the line, wherein each of the first and second disconnecting switch units comprises a mechanical switch installed on the line so as to open and close the line and a diode connected in parallel to the mechanical switch, and the two diodes are installed in opposite directions to each other.

Abstract: Provided is a dual control apparatus and control method for a high voltage direct current (HVDC) system. The dual control apparatus comprises: a first controller and a second controller operated in a dual manner, the first controller and the second controller each including: a deviation calculation unit calculating a deviation between a target value and a control value; a PI controller performing proportional control and integral control on the deviation; a first buffer storing an error value for the integral control performed by the PI controller of a relevant one of the first and second controllers; and a second buffer storing an error value for the integral control performed by the PI controller of a remaining one of the first and second controllers.