US Pat. No. 10,143,093

MODULAR APPARATUS FOR HIGH VOLTAGE DIRECT-CURRENT TRANSMISSION SYSTEM

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1. A modular apparatus for a high-voltage direct-current transmission system, the apparatus comprising:a housing forming an external shape;
a display unit disposed on an inclined surface formed at a front lower portion of the housing and inclined with respect to the ground; and
a control board disposed in an installation space at a lower portion in the housing and controlling components in response to control signals transmitted from a controller located outside the housing through a cable,
wherein the display unit shows states of the components and is connected with the cable for connection with the controller, and
wherein a connector for connection with the cable is disposed at the control board.

US Pat. No. 10,176,947

HIGH-VOLTAGE DC CIRCUIT BREAKER FOR BLOCKING DC CURRENT

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1. A high-voltage DC circuit breaker, comprising:a mechanical switch installed on a DC line;
an LC circuit including a capacitor and a reactor connected in parallel with the mechanical switch, and connected in series with each other so as to cause LC resonance;
a first semiconductor switch connected in series with the LC circuit and configured to switch a flow of current in one direction; and
a second semiconductor switch connected in parallel with the first semiconductor switch and configured to switch a flow of current in a direction opposite the one direction,
wherein, in a steady state, the first and second semiconductor switches are turned off, and a current flowing through the DC line is supplied to the capacitor to enable an initial voltage to be charged in the capacitor,
wherein, when a fault occurs on one side of the DC line, the mechanical switch is opened and the first semiconductor switch is turned on in a state in which the second semiconductor switch is turned off, a current by the initial voltage charged in the capacitor flows through an arc formed in the mechanical switch and the first semiconductor switch, and then LC resonance occurs in the LC circuit and a polarity-reversed voltage is charged in the capacitor via the LC resonance in the LC circuit,
wherein a current by the polarity-reversed voltage flows to the mechanical switch to extinguish the arc formed in the mechanical switch, and
wherein, when the arc is extinguished, both the first and second semiconductor switches are turned off, and a current flowing through the DC line is supplied to the LC circuit, so that the capacitor is recharged to the initial voltage.

US Pat. No. 10,181,387

ELECTROMAGNETIC REPULSION ACTUATOR FOR CIRCUIT BREAKER

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1. An electromagnetic repulsion actuator for a circuit breaker, comprising:a housing;
a first fixed electrode provided inside the housing and having therein an operating space open at both sides;
a pair of movable electrodes installed in the first fixed electrode at the both sides of the operating space thereof, the movable electrodes being capable of reciprocally moving and being electrically connected to the first fixed electrode;
second fixed electrodes respectively spaced apart from the first fixed electrode and installed inside the housing at both sides thereof, and selectively contacting the pair of movable electrodes to be electrically connected thereto, thereby transferring power supplied from a first side to a second side; and
actuating coils selectively moving the movable electrodes in directions of being separated from the second fixed electrodes by generating electromagnetic force from induced current.

US Pat. No. 10,177,652

POWER SUPPLY DEVICE FOR SUB-MODULE CONTROLLER OF MMC CONVERTER

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1. A power supply apparatus for a sub-module controller of a MMC, comprising:a bridge circuit unit including N (N?2, integer) energy storage units for storing a DC voltage in series-connected sub-modules in the MMC, and multiple power semiconductor devices respectively connected in parallel with the N energy storage units in a form of a bridge and connected in series with each other;
a switching unit for switching any one of a first output terminal formed at a first end of n (1?n a DC/DC converter for converting a voltage, output through the first output terminal or the second output terminal depending on switching of the switching unit, into a lower voltage than the output voltage, and supplying the lower voltage to the sub-module controller.

US Pat. No. 10,170,903

HIGH VOLTAGE DC CIRCUIT BREAKER

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1. A high-voltage DC circuit breaker for breaking a current that flows in a DC line, comprising:a main switch (110), installed on the DC line, for breaking a current of the DC line by opening when a fault occurs on one side or a remaining side of the DC line;
a nonlinear resistor (120) connected in parallel with the main switch (110);
an LC circuit (130) that is connected in series with both the main switch (110) and a first bidirectional switching element (140), and includes a capacitor (131) and a reactor (132), which are connected in series in order to generate LC resonance;
the first bidirectional switching element (140), is for switching a bidirectional current flow; and
a second bidirectional switching element (150), connected in parallel with the LC circuit (130), for switching a current flow to induce LC resonance in both directions.

US Pat. No. 10,176,939

HIGH-VOLTAGE DC CIRCUIT BREAKER FOR BLOCKING CURRENT FLOWING THROUGH DC LINES

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1. A high-voltage DC circuit breaker for blocking current flowing through a DC line, comprising:a main switch connected to the DC line, and configured to be opened when a fault occurs on a first side or a second side of the DC line, thus blocking a current flowing through the DC line;
an LC circuit connected in parallel with the main switch and provided with a capacitor and an inductor connected in series with each other to produce LC resonance;
a first switching element connected in parallel with the LC circuit and configured to perform switching so that a positive voltage or a negative voltage stored in the capacitor via the resonance produced by the LC circuit is charged, with a polarity of the positive or the negative voltage changed; and
a second switching element connected in series with the LC circuit, connected in parallel with the main switch and connected between the LC circuit and the DC line, the second switching element performing switching so that a current pulse, generated by the positive or negative voltage charged in the capacitor, is supplied to the main switch,
wherein the first switching element and the second switching element are connected in a forward direction, are each arranged in a forward or reverse direction relative to a direction of current flowing from the second side to the first side of the DC line, and are each implemented using one or more power semiconductor switches,
when the main switch is opened due to occurrence of a fault on the second side of the DC line, and an arc is formed when the main switch is opened, and the second switching element is turned on in a state in which the first switching element is turned off, so that the current pulse generated by the positive voltage stored in the capacitor of the LC circuit is supplied in a direction of a second end of the main switch, and zero current is realized in the main switch using the supplied current pulse, thus enabling the arc formed in the main switch to be extinguished, and enabling the negative voltage to be charged in the capacitor,
wherein, after the arc formed in the main switch has been extinguished, the negative voltage charged in the capacitor is charged as the positive voltage via the resonance produced by the LC circuit when the first switching element is turned on in a state in which the second switching element is turned off, and thereafter the first switching element is turned off.

US Pat. No. 10,199,988

METHOD FOR CONTROLLING POWER GRID FREQUENCY OF MULTIPLE ENERGY STORAGE SYSTEMS, AND SYSTEM THEREFOR

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1. A power grid frequency control system for controlling a power grid frequency for multiple energy storage systems using a hierarchical control structure, comprising:a plurality of energy storage systems (ESSs);
a local management system (LMS) configured to manage at least one of the energy storage systems on a local basis;
an energy storage system controller (ESS controller) configured to generally control the local management system by determining a state of the local management system, estimating an output value of at least one of the energy storage systems belonging to the local management system, and transmitting the estimated output value to each energy storage system; and
a power management system (PMS) configured to generally manage overall systems including the plurality of energy storage systems, the local management system, and the energy storage system controller, determine states of the overall systems to allow a user to participate in a power grid frequency control market by making a contract with a system operator, control an output value of the local management system, and regulate control parameters for controlling the output value, wherein, when a plurality of energy storage system controllers are provided, the power management system determines control parameters for controlling frequencies of the energy storage system controllers, sets a participating energy ratio for a frequency response and frequency regulation control depending on a frequency state on the basis of the determined control parameters, and performs the frequency response and frequency regulation control depending on the set participating energy ratio,
wherein the power management system analyzes the power grid frequency and an automatic generation control (AGC) signal, makes a normal distribution of the power grid frequency and the AGC signal within a particular time interval, calculates an output expectation value for the frequency response control and an output expectation value of the AGC signal for the frequency regulation control within the particular time interval, optimizes the participating energy ratio for the frequency response and the frequency regulation for a day, and sets a result of the optimization as the participating energy ratio for the frequency response and the frequency regulation.

US Pat. No. 10,231,363

MODULAR COOLING APPARATUS FOR HIGH-VOLTAGE DIRECT-CURRENT TRANSMISSION SYSTEM

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1. A modular cooling apparatus for a high-voltage direct-current transmission system, the apparatus comprising:a housing forming an external shape and having an internal space;
external couplers disposed through an inclined surface, which is inclined downward at a lower portion of a front of the housing, and configured to be connected with cooling water hoses;
a heat sink disposed in the internal space, and having a cooling water channel disposed therein, wherein one or more heat sources are mounted on an external surface of the heat sink and the cooling water channel is disposed adjacent to the one or more heat sources; and
internal couplers respectively disposed at an inlet and an outlet of the cooling water channel and respectively connected to the external couplers through respective internal connection pipes,
wherein the inclined surface is disposed between and respectively connected with the front and a bottom of the housings,
wherein the heat sink is disposed on an outer side of a support plate erected in the internal space, and the inlet and the outlet of the cooling water channel are formed at a lower end of the heat sink adjacent to a bottom of the internal space, and
wherein a hole is formed through a side of the housing that faces the heat sink and a louver plate is disposed over the hole.

US Pat. No. 10,230,293

POWER SUPPLY APPARATUS FOR SUB-MODULE OF MMC

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1. An apparatus for supplying power to a sub-module of a Modular Multilevel Converter (MMC), comprising:a charging unit in which an input voltage between P and N buses of the MMC is stored;
a relay unit connected in parallel with the charging unit;
a resistor connected in series with the relay unit;
a TVS diode connected in series with the resistor;
a Zener diode connected in series with the TVS diode;
a transformer for delivering the input voltage received in a primary winding to a secondary winding thereof;
a switch connected to the primary winding of the transformer in series for switching a flow of current supplied to the transformer;
a control unit for enabling current to flow to the transformer by turning on the switch upon receiving a clamping voltage of the Zener diode; and
a relay switching unit for operating the relay unit upon receiving a voltage output from the secondary winding of the transformer,
wherein, when the input voltage reaches a rated voltage, the control unit turns on the switch so that a closed circuit is formed by the switch and the primary winding of the transformer, and thereby makes the current flow through the switch and the primary winding, and then the transformer outputs the voltage as a secondary voltage, and
wherein, the relay switching unit operates to open the relay unit by using the secondary voltage and opens so that no current is applied to the control unit through the relay unit.

US Pat. No. 10,229,794

CIRCUIT BREAKER FOR INTERRUPTING DC CURRENT USING MAGNETIC FIELD

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1. A circuit breaker for interrupting a DC current using a magnetic field, comprising:a main switch installed on a DC line;
a coil wound to produce a magnetic flux in a direction perpendicular to a direction of an arc current generated when the main switch is opened;
a semiconductor switch configured to switch application of a current to the coil;
a capacitor connected in series with the semiconductor switch; and
a first diode configured to enable a current in the DC line, supplied from a first end of the main switch, to be transferred to the capacitor,
wherein, when a short circuit fault in the DC line occurs, the semiconductor switch is turned on so that a current is applied to the coil using a voltage charged in the capacitor,
wherein, when the semiconductor switch is turned on, the current is supplied to the coil through the semiconductor switch using the voltage charged in the capacitor, and the magnetic flux is produced in the direction perpendicular to the direction of the arc current, generated in the main switch, using the current supplied to the coil, to increase a resistance to the arc current, and
wherein a current in the DC line is returned to the coil through the first diode and the semiconductor switch to continuously increase the resistance to the arc current.

US Pat. No. 10,304,644

VACUUM INTERRUPTER AND DRIVING METHOD THEREFOR

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1. A vacuum interrupter, comprising:a housing with a vacuum state therein;
a first and a second movable electrodes partially accommodated within the housing and having a first and a second movable contacts disposed at a respective first end thereof, the first and second movable electrodes being capable of moving in forward/backward directions so that the first and second movable contacts contact each other or are separate from each other by movements in the forward/backward directions of the first and second electrodes;
a first and a second driving parts respectively connected to a second end of each of the first and second movable electrodes and moving the first and second movable electrodes in the forward/backward directions; and
a controller controlling movements of the first and second driving parts,
wherein the controller adjusts moving times and moving speeds of the first and second movable electrodes by adjusting times of applying current to the first and the second driving parts.

US Pat. No. 10,297,371

CAPACITOR BUSHING AND MANUFACTURING METHOD THEREFOR

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1. A capacitor bushing comprising:a central conductor having a predetermined length,
insulating layers formed by winding insulating fibers around an outer side of the central conductor so that wefts and warps constituting the insulating fibers extend obliquely with respect to a longitudinal direction of the central conductor,
conductive layers positioned between the insulating layers and including conductive fibers, and
filling layers formed by filling spaces between the insulating layers and the central conductor, between the insulating layers, and between the insulating layers and the conductive layers with an epoxy resin.

US Pat. No. 10,254,780

METHOD AND APPARATUS FOR DISTRIBUTING POWER IN ENERGY STORAGE SYSTEM

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1. An electric power distribution method in an energy storage system (ESS), comprising:computing a total power amount on a basis of a received user output target power amount and a deviation amount;
determining a power distribution power conditioning system (PCS), to which the total power amount is distributed, out of power distribution PCSs included in the ESS;
distributing the total power amount on a basis of a weight for the power distribution PCS,
wherein the deviation amount is a difference between an existing total power amount and an existing user output target power amount used in the ESS,
wherein the power distribution PCS is determined by detecting a state of charge (SoC) of a battery under control of the power distribution PCS,
wherein the weight for the power distribution PCS is determined based on a first and a second weighting factors,
wherein the first weighting factor is a relative weight for a weight decision element including a charge capacity, a charge efficiency and a discharge efficiency,
wherein the second weighting factor is a normal weight for each weight decision element computed for each power distribution PCS, and
wherein an analytic hierarchy process (AHP) is employed to compute the weight.

US Pat. No. 10,234,510

SOC MANAGEMENT SYSTEM OF ENERGY STORAGE DEVICE, AND METHOD THEREFOR

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1. A state of charge (SOC) management system for managing an energy storage system including at least one energy storage device, the SOC management system comprising a controller configured to:manage the SOC of the at least one energy storage device by performing an active power/frequency (P-f) droop control based on a droop coefficient, a reference frequency, and a dead band to determine an output power of each of the at least one energy storage device, and
adjust a charging/discharging ratio of the energy storage system by changing a position of the dead band by adjusting the reference frequency depending on the SOC of the at least one energy storage device,
wherein the P-f droop control includes:
a current SOC calculation process in which the SOC management system of the at least one energy storage device calculates the SOC of each of the at least one energy storage device belonging to the energy storage system;
an SOC position determination process in which it is determined whether or not the SOC calculated in the current SOC determination process is within a predetermined range between an upper limit (SOC+) and a lower limit (SOC?);
a reference frequency change process in which the reference frequency is changed depending on a result of the determination in the SOC position determination process on whether or not the calculated SOC (SOCP) is within the predetermined range, wherein, if the SOCP is equal to or higher than the SOC+, the reference frequency is increased, wherein, if the SOCP is equal to or lower than the SOC?, the reference frequency is decreased, and wherein, if the SOCP is positioned between the SOC+ and the SOC?, the reference frequency is maintained at an initial reference frequency without a change;
a governor free control (GFC) output process in which an output power level of the energy storage device is determined and output using the reference frequency changed in the reference frequency change process;
an SOC re-calculation process in which the SOC of the energy storage device is re-calculated on the basis of the output power level; and
an SOC position re-determination process in which the SOC recalculated in the SOC re-calculation process is compared with the current SOC calculated in the current SOC calculation process to determine whether or not the process advances to the reference frequency change process or the current SOC calculation process.

US Pat. No. 10,325,737

FAST SWITCH DEVICE

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1. A switch device, comprising:a reactor configured to move to an open position where the switch is opened and to a close position where the switch is closed;
an open coil portion configured to drive the reactor to the open position by virtue of an eddy current; and
a close coil portion configured to drive the reactor to the close position by virtue of an eddy current,
wherein the switch is configured to apply an electric current to the close coil portion oppositely to a direction of an electric current flowing through the open coil portion in order to brake the reactor during an open operation for driving the reactor to the open position, and further configured to apply an electric current to the open coil portion oppositely to a direction of an electric current flowing through the close coil portion in order to brake the reactor during a close operation for driving the reactor to the close position,
wherein the switch is configured to determine a timing of applying the electric current for braking the reactor based on a position of the reactor and a current rise time of the electric current flowing through the open coil portion or the close coil portion,
wherein the open coil portion has a first Thomson coil and a first capacitor connected to the first Thomson coil in parallel, and the open coil portion causes an electric current to flow to the first Thomson coil by using a voltage stored in the first capacitor to drive the reactor toward the open position by virtue of an eddy current induced by the electric current flowing through the first Thomson coil,
wherein the close coil portion has a second Thomson coil and a second capacitor connected to the second Thomson coil in parallel, and the close coil portion causes an electric current to flow to the second Thomson coil by using a voltage stored in the second capacitor to drive the reactor toward the close position by virtue of an eddy current induced by the electric current flowing through the second Thomson coil, and
wherein the second Thomson coil has fewer turns and lesser resistance than those of the first Thomson coil.

US Pat. No. 10,305,394

APPARATUS FOR SUPPLYING POWER TO SUB-MODULE OF MMC

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1. An apparatus for supplying power to sub-modules by using voltage charged in a charger from input voltage of P-N bus bars of an MMC (Modular Multilevel Converter), the apparatus comprising:a relay disposed between the P-N bus bars of the MMC and including a break contact switch;
a resistor (R) connected in series to the relay;
a TVS diode (TD) connected in series to the resistor;
a Zener diode (ZD) connected in series to the TVS diode (TD);
a transformer transmitting the input voltage of the P-N bus bars from a primary side to a secondary side thereof;
a semiconductor switch switching a current flow to the transformer;
a controller turning on the semiconductor switch such that the current flows to the transformer when clamping voltage of the Zener diode (ZD) is input;
a relay switch driving the break contact switch of the relay when receiving output voltage from the secondary side of the transformer; and
a circuit breaker connected in series to the relay and breaking a circuit when current flowing through the break contact switch of the relay is larger than a predetermined reference current,
wherein, when the input voltage reaches a rated voltage for starting the apparatus, the controller turns on the semiconductor switch so that a closed circuit is formed by the semiconductor switch and the primary side of the transformer,
wherein, when the semiconductor switch is turned on, the current flows in the closed circuit, and then the transformer transmits the input voltage at the primary side to the secondary side, and the output voltage from the secondary side is input to the relay switch and used as power for operating the apparatus,
wherein the relay switch operates to open the break contact switch of the relay by using the output voltage of the secondary side so that no current is applied to the controller through the relay,
wherein, after the break contact switch is opened, the controller receives the output voltage from the secondary side of the transformer and operates the apparatus by using the output voltage, and
wherein, when the break contact switch of the relay is changed into a short state due to a short at the secondary side of the transformer in a normal operation state and, when current flowing through the break contact switch is larger than the predetermined reference current, the circuit breaker breaks the circuit.

US Pat. No. 10,348,181

POWER CONTROL APPARATUS FOR SUB-MODULE OF MMC CONVERTER

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1. A power control apparatus for sub-modules in a Modular Multilevel Converter (MMC), comprising:at least one first resistor connected between P and N buses of the MMC;
a second resistor connected in series with the at least one first resistor;
a switch connected in series with the second resistor;
a third resistor connected in parallel with the second resistor and the switch, wherein the second resistor and the switch are connected in series;
a Zener diode connected in parallel with the third resistor; and
a DC/DC converter connected between both ends of the Zener diode and configured to convert voltage across both ends of the Zener diode into a low voltage, and supply the low voltage to the sub-modules,
wherein a magnitude of current flowing through the Zener diode is controlled depending on ON/OFF switching of the switch,
wherein voltage across the P and N buses increases or decreases in a range from 0 to a preset maximum voltage, and in a low-voltage section, in which the voltage across the P and N buses ranges from 0 V to a first voltage, the switch is turned off, thus preventing current from flowing through the second resistor.