Abstract: A voltage source converter includes a black start control unit and cells, where each cell includes a first switch between a first end of a cell capacitor and a first cell terminal, a second switch between a second end of the cell capacitor and the first cell terminal, where a second cell terminal is provided via the first or the second end of the cell capacitor, a first power supply unit and a second power supply unit, where the black start control unit is configured to perform, after the initial application of a DC voltage to a cell terminal of a cell and the subsequent initial charging of the chargeable power supply unit of one of the switches, charging of an uncharged power supply unit of the other switch through repeatedly turning on and off the switch with initially charged power supply unit.

Abstract: A method and a device to discharge cell capacitors in a cell based voltage source converter. Each cell has switching elements in half bridge or full bridge configuration and a capacitor in parallel to the half or full bridge. Each cell has two terminals, whereof at least one is between two switching elements. The converter has AC and DC terminals, with the possibility to connect each of the terminals to ground, via a further switching element. A resistor is implemented into at least one of the ground connections. To discharge to capacitors, the switching elements in the respective cells are configured such, that the capacitor is in parallel connection to the terminals. The capacitors are thus discharged via the resistor to ground.

Abstract: A switching module, intended to be used in a medium or high voltage DC breaker or a DC current limiter, includes at least one power semiconductor switching element, a gate unit arranged to turn the at least one power semiconductor switching element on and off, respectively, according to a switching control signal, and an energy storage capacitor arranged to provide power to a power supply input of the gate unit. The switching module further includes a power transformation device arranged to receive an optical power signal, to transform the optical power signal into an electrical power signal and to provide the electrical power signal to the energy storage capacitor.

Abstract: A device for converting a DC voltage into an AC voltage and vice versa comprises a control system to control the voltage conversion and at least one phase leg (1) with a first (Uvp1) voltage source connected in series between a first DC terminal (4) and a first AC terminal (6) and with a second (Uvn1) voltage source connected in series between the first AC terminal (6) and a second DC terminal (5). Each of the voltage sources comprises at least a first and a second submodule (15) in series-connection, where each submodule (15) comprises at least two power electronic switches (16) connected in parallel with at least one capacitor (17).

Abstract: An apparatus for controlling a voltage source converter with at least two bridges of semiconducting self commutating elements connected in anti-parallel with a diode, including circuitry for producing a switching control pulse train to form a fundamental frequency, circuitry for effecting a switching order and circuitry for detecting a switching event.

Abstract: In a method for control of a converter for conversion of dc voltage into ac voltage or dc voltage and vice versa, in which an output of the converter may alternatively be connected to a positive pole, a negative pole or a center of a dc voltage side of the converter in the form of different so-called main states, there is carried out, when changing between main states via a so-called minor commutation loop, an extra sequence in the form of a delayed turn-on of semiconductor elements in one unit of the converter relative to semiconductor elements in another unit in a pair of units of the converter.

Abstract: A device in a valve on high voltage potential level and in a high voltage converter station comprises members arranged on high voltage level and adapted to detect parameters of a voltage divider circuit consisting of resistances (24, 25) and capacitors (27, 28) connected in series and across each thyristor of said valve. The capacitors are of self-healing type, in which from the point of time for occurring of a possible fault thereof the capacitance is gradually reduced, and said members are adapted to carry out measurements so as to determine whether the capacitance of the capacitors is changed over the time.

Abstract: A device for supervising the cooling of a cooling system of a valve of a high voltage converter station located on high voltage potential level comprises members (31) located on high voltage potential level and adapted to detect the temperature at cooling blocks (32) of the valve on high voltage potential level and send values so detected to first control units (3) for controlling semiconductor components (4) of the valve. The first control units have means (20) for treating said values detected and the first control units are adapted to send data resulting from said treatment to an arrangement (16) for supervising said valve located on low potential level.