Abstract: Embodiments are generally based on employing a power transmission line in a HVDC link to provide auxiliary power to one of the ends of the HVDC link for facilitating a black start thereof when the HVDC link is de-energized, i.e. when at least one of the HVDC converter stations is de-energized and there is no transmission of power between inverter and rectifier HVDC converter stations on each side of the HVDC link. A relatively small amount of power can be conveyed towards one of the HVDC converter stations via the power transmission line so as to provide power to any auxiliary system(s) of the converter station, for example prior to a black start of the converter station being carried out.

Abstract: Embodiments are generally based on employing a power transmission line in a HVDC link to provide auxiliary power to one of the ends of the HVDC link for facilitating a black start thereof when the HVDC link is de-energized, i.e. when at least one of the HVDC converter stations is de-energized and there is no transmission of power between inverter and rectifier HVDC converter stations on each side of the HVDC link. A relatively small amount of power can be conveyed towards one of the HVDC converter stations via the power transmission line so as to provide power to any auxiliary system(s) of the converter station, for example prior to a black start of the converter station being carried out.

Abstract: It is provided a power converter for transferring power between a high voltage DC connection and a high voltage AC connection. The power converter includes a power converter assembly including: a first converter arm, a first reactor, a second reactor and a second converter arm, connected serially between the positive and negative terminals of the DC connection. The high voltage AC connection is provided between the first reactor and the second reactor. Each one of the converter arms includes a plurality of converter cells and each one of the converter cells includes a switching element and an energy storage element. Both the first reactor and the second reactor are oil filled reactors.

Abstract: It is provided a power converter for transferring power between a high voltage DC connection and a high voltage AC connection. The power converter includes a power converter assembly including: a first converter arm, a first reactor, a second reactor and a second converter arm, connected serially between the positive and negative terminals of the DC connection. The high voltage AC connection is provided between the first reactor and the second reactor. Each one of the converter arms includes a plurality of converter cells and each one of the converter cells includes a switching element and an energy storage element. Both the first reactor and the second reactor are oil filled reactors.

Abstract: A filter apparatus includes at least one filter, each filter being tunable and including at least one capacitor arrangement. The capacitor arrangement includes a plurality of first capacitors, a plurality of second capacitors, and a plurality of switches. Each switch is switchable between a non-conducting mode and a conducting mode. The plurality of second capacitors and the plurality of switches are arranged to connect or disconnect the second capacitors on different potentials in order to tune the filter by adjusting the capacitance of the filter. An electrical power transmission or distribution system includes such a filter apparatus. A method is provided for filtering harmonics in an electrical power transmission or distribution system by means of such a filter apparatus.

Abstract: An arrangement for controlling the electric power transmission in a high voltage direct current, HVDC, power transmission system includes at least one HVDC transmission or distribution line for carrying direct current, DC, and the arrangement includes an apparatus connectable to the HVDC transmission or distribution line, the apparatus being arranged to control the direct current of the HVDC transmission or distribution line by introducing a DC voltage in series with the HVDC transmission or distribution line. The arrangement includes a protection device for protecting the apparatus against over-current or overvoltage occurrences. The protection device includes a bypass device connectable to the HVDC transmission or distribution line and connected in parallel with the apparatus. The bypass device is arranged to be in a non-conducting mode and arranged to be set to a conducting mode.

Abstract: A converter building including at least one room having a solid room wall enclosing an interior space and an electrical active part contained in the interior space, the room wall having at least one opening, which is designed such that it allows a human to enter the interior space. The opening is sealable, the room wall encloses the interior space in a gas-tight manner when the opening is sealed, and the interior space contains a dielectric insulation medium including a dielectric insulation component other than air.

Abstract: A filter apparatus includes at least one filter, each filter being tunable and including at least one capacitor arrangement. The capacitor arrangement includes a plurality of first capacitors, a plurality of second capacitors, and a plurality of switches. Each switch is switchable between a non-conducting mode and a conducting mode. The plurality of second capacitors and the plurality of switches are arranged to connect or disconnect the second capacitors on different potentials in order to tune the filter by adjusting the capacitance of the filter. An electrical power transmission or distribution system includes such a filter apparatus. A method is provided for filtering harmonics in an electrical power transmission or distribution system by means of such a filter apparatus.

Abstract: An arrangement for controlling the electric power transmission in a high voltage direct current, HVDC, power transmission system includes at least one HVDC transmission or distribution line for carrying direct current, DC, and the arrangement includes an apparatus connectable to the HVDC transmission or distribution line, the apparatus being arranged to control the direct current of the HVDC transmission or distribution line by introducing a DC voltage in series with the HVDC transmission or distribution line. The arrangement includes a protection device for protecting the apparatus against over-current or overvoltage occurrences. The protection device includes a bypass device connectable to the HVDC transmission or distribution line and connected in parallel with the apparatus. The bypass device is arranged to be in a non-conducting mode and arranged to be set to a conducting mode.

Abstract: A converter building including at least one room having a solid room wall enclosing an interior space and an electrical active part contained in the interior space, the room wall having at least one opening, which is designed such that it allows a human to enter the interior space. The opening is sealable, the room wall encloses the interior space in a gas-tight manner when the opening is sealed, and the interior space contains a dielectric insulation medium including a dielectric insulation component other than air.

Abstract: A modular HVDC converter system including a high voltage direct current network, and at least two DC/AC converters being connected in series to the HVDC network. Each of the DC/AC converters is arranged to provide AC to a separate AC load.

Abstract: A modular HVDC converter system including a high voltage direct current network, and at least two DC/AC converters being connected in series to the HVDC network. Each of the DC/AC converters is arranged to provide AC to a separate AC load.

Abstract: An installation for power transmission by high-voltage direct current has at least two converter stations which are interconnected by a dc line (DC), at least one station (SR1) having a line protection device (LP) adapted to detect a ground fault on the dc line and, when a ground fault is detected, to achieve a reduction of the voltage (U.sub.D) and the current (I.sub.D) of the line and thereafter to make a restart attempt. The installation has, in addition, a detection circuit (FD) for detection of a permanent low-impedance ground fault on the dc line. The detection circuit is activated after an intervention by the line protection device. During a detection interval, the detection circuit causes one of the stations (SR1) to feed a current into the line.

Abstract: In a method for control of an installation for transmission of high-voltage direct current in dependence on at least one stress parameter for a valve in a converter included in the installation and controlled by control equipment (CE1, CE2), a value (PDR, PDI, UMAX, TRC, TTC) of the stress parameter is continuously calculated, based on predetermined relationships (f1, f2, g1R, g2R, g1I, g2I, h1, h2) and in dependence on measured values (UN, .alpha., .gamma., ID, TO, TI, RECT/INV) of the operating parameters of the installation. At least one influencing signal (HTH, HCC, HCR) is generated in dependence on a comparison between the calculated value and at least one comparison value for the parameter, and the influencing signal is supplied to the control equipment to influence this in a direction which limits the value of the stress parameter.The member (HAS) comprises a monitoring device (PD, UA, TR, TT) for calculating the value of the stress parameter.

Abstract: An installation for transmission of high-voltage direct current comprises a converter (SR1) which is controlled by a control unit (CU1). The control unit comprises a quotient-forming member, which forms a current order (IO) for the current (Id) in the dc connection of the installation in dependence on the quotient between a power order (PO) and a calculating value (UDF) of the direct voltage (Ud) at the converter, and a low-pass filter with a bandwidth (1/T1, 1/T2) capable of being controlled, which forms the calculating value as a filtered measured value (UD) of the direct voltage. The control unit comprises a signal-forming member which forms a state signal (FC), indicating that a short-circuit fault has occurred. The state signal influences the bandwidth of the low-pass filter such that the bandwidth is temporarily changed from a smaller value (1/T1) to a larger value (1/T2).