Abstract: A direct current breaker for a high voltage direct current application includes: two high voltage electron tubes arranged in an anti-parallel connection, and a control circuit for receiving, from a control system, infrared pulses including control information, the control circuit further including a device configured to convert the infrared pulses into electrical control signals, for controlling a switching status of the direct current breaker. An electrical power system includes such direct current breaker.

Abstract: A direct current breaker for a high voltage direct current application includes: two high voltage electron tubes arranged in an anti-parallel connection, and a control circuit for receiving, from a control system, infrared pulses including control information, the control circuit further including a device configured to convert the infrared pulses into electrical control signals, for controlling a switching status of the direct current breaker. An electrical power system includes such direct current breaker.

Abstract: A converter cell (110; 120) is provided. The converter cell comprises a capacitor (113; 123), a first (111; 121) and a second (112; 122) switching element connected in series, a first (114; 124) and a second (115; 125) connection terminal for connecting the converter cell to an external circuit, a bypass element (113; 123) connected in parallel to the capacitor, and a control unit (117). The control unit is arranged for closing, in response to detecting a condition which results in an uncontrolled charging of the capacitor, the bypass element. This is advantageous in that an uncontrolled charging of the cell capacitor, due to a failure of any one of the switching elements comprised in the converter cell, or a gate unit controlling the switching elements, may be prevented. Thereby, the risk for an over-voltage failure of the capacitor is mitigated. Further, a method of a converter cell is provided.

Abstract: The present invention relates to an HVDC switchyard arranged to interconnect a first part of a DC grid with a second part of the DC grid. By means of the invention, a first part of the DC grid is connected to the busbars of the HVDC switchyard via a fast DC breaker, while further part(s) of the DC grid are connected to the busbars of the HVDC switchyard by means of switchyard DC breakers of lower breaking speed. By use of the inventive HVDC switchyard arrangement, the cost for the HVDC switchyard can be considerably reduced, while adequate protection can be provided. In one embodiment, the fast DC breaker is an HVDC station DC breaker forming part of an HVDC station. In another embodiment, the fast DC breaker is a switchyard DC breaker.

Abstract: A plant for transmitting electric power through HVDC includes two converter stations interconnected by a bipolar direct voltage network and each connected to an alternating voltage network. Each converter station has a Voltage Source Converter with switching cells each including at least one energy storing capacitor. The Voltage Source Converters are configured to utilize a direct voltage having a higher magnitude for a first of the poles than for a second thereof with respect to ground.

Abstract: A device (13) to break an electrical current flowing through a power transmission or distribution line (14) comprises a parallel connection of a main breaker (8) and a non-linear resistor (11), where the main breaker (8) comprises at least one power semiconductor switch of a first current direction. The device (13) further comprises a series connection of a high speed switch (10) comprising at least one mechanical switch and of an auxiliary breaker (9), the auxiliary breaker having a smaller on-resistance than the main breaker (8) and comprising at least one power semiconductor switch of the first current direction. The series connection is connected in parallel to the parallel connection. In a method to use the device (13) first the auxiliary breaker (9) is opened, thereby commutating the current to the main breaker (8), afterwards the high speed switch (10) is opened and afterwards the main breaker (8) is opened thereby commutating the current to the non-linear resistor (11).

Abstract: A DC cable for high voltages having at least an inner conductor surrounded by an insulating layer configured to take the voltage to be taken between the conductor and the surroundings of the cable. The insulating layer is formed by a plurality of superimposed film-like layers of insulating material each having isolated areas of metal on top thereof. The metal areas of consecutive such film-like layers are at least partially overlapping each other as seen in the radial direction of the cable so as to create a large number of small capacitors in said insulating layer of the cable.

Abstract: A device for converting a DC voltage into an AC voltage and vice versa comprises at least one phase leg with a first voltage source and a first inductor connected in series between a first DC terminal and a first AC terminal and with a second inductor and a second voltage source connected in series between the first AC terminal and a second DC terminal, where each of the voltage sources comprises at least a first and a second submodule in series-connection, each submodule comprising at least one power electronic switch connected in parallel with at least one capacitor. In the device, a passive electronic filter is arranged between the first and the second inductor as well as the first AC terminal for reducing harmonics in a circulating current.

Abstract: A converter for converting alternating voltage into direct voltage and vice versa in a converter station of a high voltage transmission system. A series connection of converter valves includes power semiconductor devices connected in series and arranged in superimposed layers. The valves are arranged on top of each other in a column. Coolant liquid conducting tubes are in an extension over at least one part of the circumference of the column having no connections to cooling blocks for cooling the devices made of metal. Such metal tubes are arranged in the part for over this part of the column circumference forming an electric field shielding screen. The coolant liquid conducting tubes are when extending over parts of a circumference of the column where connections are made to cooling blocks made of an electrically insulating material. An electric field shield is arranged outside the column over these parts.

Abstract: The present invention relates to an HVDC switchyard arranged to interconnect a first part of a DC grid with a second part of the DC grid. By means of the invention, a first part of the DC grid is connected to the busbars of the HVDC switchyard via a fast DC breaker, while further part(s) of the DC grid are connected to the busbars of the HVDC switchyard by means of switchyard DC breakers of lower breaking speed. By use of the inventive HVDC switchyard arrangement, the cost for the HVDC switchyard can be considerably reduced, while adequate protection can be provided. In one embodiment, the fast DC breaker is an HVDC station DC breaker forming part of an HVDC station. In another embodiment, the fast DC breaker is a switchyard DC breaker.

Abstract: A Voltage Source Converter having at least one phase leg connected to opposite poles of a direct voltage side of the converter and comprising a series connection of switching cells has inductance means comprising a plurality of inductors (23) built in in said series connection of switching cells (7?) and connected in series with these cells by being connected to terminals (14, 15) thereof.

Abstract: A high voltage dry-type reactor is series-connected via a first terminal to an AC supply voltage and via a second terminal to the AC phase terminal of a high voltage converter and includes a cylindrical coil of insulated wire. In order to protect the reactor from a damaging DC field, the reactor further includes a metallic or resistive electrostatic shield which is connected to a same DC potential as the converter.

Abstract: A plant for transmitting electric power includes a high voltage DC line, a DC breaker connected in series therewith and configured to break a fault current upon occurrence of a fault, a device configured to detect occurrence of a fault current, a control unit configured to control the DC breaker for protecting equipment connected to the DC line upon occurrence of the fault current and a device configured to dissipate energy stored in a faulty current path of the DC line between the location and the device's upon occurrence of the fault to the moment of the control of the DC breaker. The energy dissipating device includes a series connection of an energy consuming braking resistor and a free-wheeling rectifying member connected between ground and the DC line to conduct current while forming a free-wheeling path therethrough upon the control of the DC breaker upon occurrence of the fault.

Abstract: The invention concerns a converter as well as a cooling device and a method for cooling at least a first and a second group of electrically interconnected electrical components (SWA1, SWA2, SWA3, SWA4, SWA5, SWA6, SWA7, SWA8, SWB1, SWB2, SWB3, SWB4, SWB5, SWB6, SWB7, SWB8) in the converter, where the first and second groups are placed on opposite sides of a conductor leading to a connection terminal of the converter. The cooling device (22) comprises a first transporting arrangement (HSA1, HSA2, HSA3, HSA4, HSA5, HSA6, HSA7, HSA8, HSA9, COA1, COA2, COA3, COA4, COA5, COA6, COA7, COA8) transporting cooling medium (M) past the first group and a second transporting arrangement (HSB1, HSB2, HSB3, HSB4, HSB5, HSB6, HSB7, HSB8, HSB9, COB1, COB2, COB3, COB4, COB5, COB6, COB7, COB8) transporting the same cooling medium past the second group.

Abstract: A Voltage Source Converter having at least one phase leg connected to opposite poles of a direct voltage side of the converter and comprising a series connection of switching elements including at least one energy storing capacitor and configured to obtain two switching states, namely a first switching state and a second switching state, in which the voltage across said at least one energy storing capacitor and a zero voltage, respectively, is applied across the terminals of the switching element, has semiconductor chips of said switching elements arranged in stacks comprising each at least two semiconductor chips. The converter comprises an arrangement configured to apply a pressure to opposite ends of each stack.

Abstract: A device (13) to break an electrical current flowing through a power transmission or distribution line (14) comprises a parallel connection of a main breaker (8) and a non-linear resistor (11), where the main breaker (8) comprises at least one power semiconductor switch of a first current direction. The device (13) further comprises a series connection of a high speed switch (10) comprising at least one mechanical switch and of an auxiliary breaker (9), the auxiliary breaker having a smaller on-resistance than the main breaker (8) and comprising at least one power semiconductor switch of the first current direction. The series connection is connected in parallel to the parallel connection. In a method to use the device (13) first the auxiliary breaker (9) is opened, thereby commutating the current to the main breaker (8), afterwards the high speed switch (10) is opened and afterwards the main breaker (8) is opened thereby commutating the current to the non-linear resistor (11).

Abstract: The invention concerns a converter as well as a cooling device and a method for cooling at least a first and a second group of electrically interconnected electrical components (SWA1, SWA2, SWA3, SWA4, SWA5, SWA6, SWA7, SWA8, SWB1, SWB2, SWB3, SWB4, SWB5, SWB6, SWB7, SWB8) in the converter, where the first and second groups are placed on opposite sides of a conductor leading to a connection terminal of the converter. The cooling device (22) comprises a first transporting arrangement (HSA1, HSA2, HSA3, HSA4, HSA5, HSA6, HSA7, HSA8, HSA9, COA1, COA2, COA3, COA4, COA5, COA6, COA7, COA8) transporting cooling medium (M) past the first group and a second transporting arrangement (HSB1, HSB2, HSB3, HSB4, HSB5, HSB6, HSB7, HSB8, HSB9, COB1, COB2, COB3, COB4, COB5, COB6, COB7, COB8) transporting the same cooling medium past the second group.

Abstract: A DC cable for high voltages having at least an inner conductor surrounded by an insulating layer configured to take the voltage to be taken between the conductor and the surroundings of the cable. The insulating layer is formed by a plurality of superimposed film-like layers of insulating material each having isolated areas of metal on top thereof. The metal areas of consecutive such film-like layers are at least partially overlapping each other as seen in the radial direction of the cable so as to create a large number of small capacitors in said insulating layer of the cable.

Abstract: An air-core reactor with natural-air cooling of a winding includes first open spaces to let air flow through the winding in parallel with an axis of symmetry of the reactor and second open spaces crossing the first open spaces to let air flow through the winding angular to the axis of symmetry. A ventilation unit to produce a forced-air flow is arranged in such a way to the air-core reactor that a first part of the forced-air flow enters one of the first or second open spaces and at least one guiding element is arranged with respect to the crossing of the first and the second open spaces in such a way that the first part of the forced-air flow leaves and a second part of the forced-air flow enters the one of the first or second open spaces. A shielding element is arranged at another crossing of the first and the second open spaces so that substantially no air can leave or enter the one of the first or second open spaces.

Abstract: A high voltage bushing for a high voltage device containing insulating liquid includes a voltage grading shield, improving performance and facilitating manufacturing.