A multi-pulse line-interphase transformer converter includes an electric part that includes magnetic components configured to be connected to a three-phase AC grid, and an electric part that includes a multi-phase voltage system configured to be connected to a common DC capacitor. The electric part splits each AC grid phase n times into two phases, resulting in a plurality of intermediate phases at an internal interface, each intermediate phase corresponding to a pulse of the multi-pulse line-interphase transformer converter. The intermediate phases are connected to the multi-phase voltage system. The multi-phase voltage system comprises bridges with actively controlled switches. The bridges are connected in parallel to the common DC capacitor.

Embodiments of the disclosure include an electrical assembly. The electrical assembly can include a converter including a DC side and an AC side, the DC side configured for connection to a DC network, the AC side configured for connection to an AC network, the converter including at least one switching element; a circuit interruption device operably connected to the AC side of the converter; a DC voltage modification device operably connected to the DC side of the converter, the DC voltage modification device including a DC chopper; and a controller configured to selectively control the or each switching element, the circuit interruption device and the DC voltage modification device, wherein the controller is configured to be responsive to a converter internal fault by carrying out a fault operating mode.

A converter includes first and second transistors coupled between first and second nodes, and first and second thyristors coupled between the first and second nodes. The converter is controlled for operation to: in first periods, turn the first transistor and second thyristor on and turn the second transistor and the first thyristor off, and in second periods, turn the first transistor and the second thyristor off and turn the second transistor and the first thyristor on. Further control of converter operation includes, for a third period following each first period, turning the first and second transistors off, turning the second thyristor off, and injecting a current into the gate of the first thyristor. Additional control of converter operation includes, for a fourth period following each second period, turning the first and second transistors off, turning the first thyristor off, and injecting a current into the gate of the second thyristor.

An electric power supply apparatus for a user device, in particular for steel industry applications, that includes means for connection to an electricity grid for supplying a mains voltage and a mains current, and at least one electric line for connecting the electricity grid to the user device, wherein the electric line includes one or more electric apparatuses located between the electricity grid and the user device.

In the field of high voltage direct current (HVDC) power transmission networks there is a need for an improved power converter. A power converter, for use in a HVDC power transmission network, comprises first and second DC terminals, for connection in use to a DC network and between which extends at least one converter limb. The or each converter limb includes first and second limb portions which are separated by an AC terminal, for connection in use to an AC network. Each limb portion includes a switching valve, and the power converter including a controller programmed to control switching of the switching valves to control the flow of a converter current (I.sub.max) through the power converter and thereby in-use transfer power between the power converter and the AC network. The power transferred between the power converter and the AC network has an active component and a reactive component. The controller is further programmed in use to: (i) prioritize to a first extent the transfer of reactive power between the power converter and the AC network during a first operating condition, when the AC voltage (V) of the AC network lies outside a desired operating range, by allowing up to a first amount of the converter current (I.sub.max) to be a reactive current; and (ii) prioritize to a second extent, less than the first extent, the transfer of reactive power between the power converter and the AC network during a second operating condition, when the AC voltage (V) of the AC network lies within the desired operating range, by limiting the amount of converter current (I.sub.max) that can be a reactive current to a second amount, less than the first amount, the second amount being determined according to a measured operating frequency of the AC network.

An inverter-charger combination includes plurality of first and second switching elements, a capacitor, and a dual active bridge, connected in parallel to one another. The first and the second switching elements are connected in series to form switching subassemblies that are disposed in parallel and are connected to an AC source. Each of the first and the second switching elements has a first and a second contactor, and, when the first contactor is open and the second contactor is closed, an electric current flows from a rechargeable energy storage system (RESS) in direct current form to a load in AC form through the switching subassemblies to provide power to the load, and when the first contactor is closed and the second contractor is open, an electric current flows from the AC source in AC form to the RESS in DC form through the switching subassemblies to charge the RESS.

A method of operating a thyristor-based line-commutated multi-phase power converter on a multi-phase AC voltage connection point, which is supplied by an AC voltage network. Between the AC voltage connection point and an AC voltage connection of the power converter, a series circuit of modules is arranged for each phase. Each of the series circuits has a first electronic switching element, a second electronic switching element, and an electric energy storage device. The voltages of the phases of the AC voltage connection point are measured and, if an undervoltage is detected on a phase of the AC voltage connection point, an additional voltage adding to the voltage of that phase is generated by way of the series circuit of modules allocated to that phase in such a way that the voltage of that phase is increased, at least temporarily.

A multiphase converter topology is used for the transmission of electrical energy from an AC voltage input with m grid phase connections to a DC voltage output or vice versa. It has a power part with half-bridges for switching currents, an AC voltage filter between the power part and the AC voltage input, and DC voltage block(s) connected between the power part and the DC output. The AC voltage filter has alternating voltage filter stage(s) with m+1 input connections, m+1 output connections and a ground connection. The m grid phase connections are thereby connected in parallel to one another and form a first phase connection for the connection of a single-phase AC voltage. A neutral conductor connection of the AC voltage filter forms a neutral conductor connection of the AC voltage input and a second phase connection for the connection of the single-phase AC voltage.

A multiphase converter topology is used for the transmission of electrical energy from an AC voltage input with m grid phase connections to a DC voltage output or vice versa. It has a power part with half-bridges for switching currents, an AC voltage filter between the power part and the AC voltage input, and DC voltage block(s) connected between the power part and the DC output. The AC voltage filter has alternating voltage filter stage(s) with m+1 input connections, m+1 output connections and a ground connection. The m grid phase connections are thereby connected in parallel to one another and form a first phase connection for the connection of a single-phase AC voltage. A neutral conductor connection of the AC voltage filter forms a neutral conductor connection of the AC voltage input and a second phase connection for the connection of the single-phase AC voltage.

A frequency converter with a rectifier on an input side and a backup capacitor arranged downstream of the rectifier. Input-side phases of the rectifier feed the backup capacitor via multiple half-bridges of the rectifier. The input-side phases are connected to grid-side phases of a multiphase supply grid via a pre-circuit. Each grid-side phase is connected to an input-side phase within the pre-circuit via a phase capacitor. Each grid-side phase is additionally directly connected to another input-side phase within the pre-circuit via a switch and the grid-side phases are short-circuited with the input-side phases when the switches are closed. Each phase capacitor connects two grid-side phases or two input-side phases together. The frequency converter has a control apparatus which keeps the switches open when pre-charging the backup capacitor and closes the switches when a specified charge state of the backup capacitor is reached.