Abstract: A converter and a method of operating a converter. The converter comprising a DC link capacitor, an upper arm (S1) and a lower arm (S4) with switching cells in series, an upper switch (S2) and a lower switch (S3). The upper switch (S2) and the lower switch (S3) are connected together and the connection point forming an output voltage terminal (a). The converter comprising further an upper valve component and a lower valve component, which are arranged such that the upper valve component allows current from the center point of the DC link capacitor towards the upper arm and the lower valve component allows current from the lower arm towards center point of the DC link capacitor. A current path through the upper valve component or the lower valve component comprises inductance to form a resonance circuit.

Abstract: A power supporting arrangement includes a DC network having a first DC line with a first DC potential, a second DC line with a second DC potential, and an energy storage system that includes a first energy storage unit connected in a branch between the first and the second DC lines. A first group of phase arms is connected in a wye-configuration between the power grid and the first DC line and a second group of phase arms connected in a wye-configuration between the power grid and the second DC line. The first and second groups of phase arms are controllable as a voltage source converter. A third group of phase arms is connected to the power grid in a wye-configuration. The third group of phase arms have a neutral point and being controllable to support the power grid with reactive power.

Abstract: A voltage source converter is configured to generate a pulse train using two voltage levels. The voltage source converter includes a first converter arm coupled between a junction and a first DC terminal having a first voltage level and a second converter arm coupled between the junction and a second DC terminal having a second voltage level. At least one of the first and second converter arms comprises cells. A string of capacitors is coupled between the first and second DC terminals. A control unit is configured to control a group of cells used in a transition between the first and second voltage levels for commutating a current running through a corresponding one of the first and second converter arms involved in the transition.

Abstract: A converter and a method of operating a converter. The converter comprising a DC link capacitor, an upper arm (S1) and a lower arm (S4) with switching cells in series, an upper switch (S2) and a lower switch (S3). The upper switch (S2) and the lower switch (S3) are connected together and the connection point forming an output voltage terminal (a). The converter comprising further an upper valve component and a lower valve component, which are arranged such that the upper valve component allows current from the center point of the DC link capacitor towards the upper arm and the lower valve component allows current from the lower arm towards center point of the DC link capacitor. A current path through the upper valve component or the lower valve component comprises inductance to form a resonance circuit.

Abstract: A protection arrangement for a multiphase uninterruptible power supply system including a vacuum circuit breaker connected in series with an inductive element, where the inductive element includes, for every phase, two series-connected magnetically coupled windings separated by a tap point. The protection arrangement includes one first group of protective components per phase, each first group including a first protective component having a first end connected to a link between the vacuum circuit breaker and the inductive element and a second end connected to a corresponding tap point, where at least one protective component in each first group is a surge arrester.

Abstract: A voltage source converter is configured to generate a pulse train using two voltage levels. The voltage source converter includes a first converter arm coupled between a junction and a first DC terminal having a first voltage level and a second converter arm coupled between the junction and a second DC terminal having a second voltage level. At least one of the first and second converter arms comprises cells. A string of capacitors is coupled between the first and second DC terminals. A control unit is configured to control a group of cells used in a transition between the first and second voltage levels for commutating a current running through a corresponding one of the first and second converter arms involved in the transition.

Abstract: The present disclosure relates to a semiconductor switch leg S for a Power Electronic (PE) converter (1). The switch leg comprises a plurality of parallel connected semiconductor devices Sa-d. Each semiconductor device is connected with a positive conductor a-d+ connecting the semiconductor device to a positive terminal of an energy storing device (2) of the converter, and a negative conductor a-d-connecting the semiconductor device to a negative terminal of the energy storing device (2) of the converter, the semiconductor device together with the positive conductor and the negative conductor forming a current path across the energy storing device.

Abstract: The present disclosure relates to a semiconductor switch leg S for a Power Electronic (PE) converter (1). The switch leg comprises a plurality of parallel connected semiconductor devices Sa-d. Each semiconductor device is connected with a positive conductor a-d+ connecting the semiconductor device to a positive terminal of an energy storing device (2) of the converter, and a negative conductor a-d-connecting the semiconductor device to a negative terminal of the energy storing device (2) of the converter, the semiconductor device together with the positive conductor and the negative conductor forming a current path across the energy storing device.

Abstract: A protection arrangement for an uninterruptible power supply system including at least one vacuum circuit breaker connected in series with an inductive element, the protection arrangement including a first bypass branch and a first grounding branch, the first bypass branch being connected in parallel with the inductive element and including two series-connected protective components of a first type and a bypass branch midpoint between them, where the first grounding branch is connected between the bypass branch midpoint and ground and includes a first grounding surge arrester.

Abstract: A protection arrangement for a multiphase uninterruptible power supply system including a vacuum circuit breaker connected in series with an inductive element, where the inductive element includes, for every phase, two series-connected magnetically coupled windings separated by a tap point. The protection arrangement includes one first group of protective components per phase, each first group including a first protective component having a first end connected to a link between the vacuum circuit breaker and the inductive element and a second end connected to a corresponding tap point, where at least one protective component in each first group is a surge arrester.

Abstract: A protection arrangement for an uninterruptible power supply system including at least one vacuum circuit breaker connected in series with an inductive element, the protection arrangement including a first bypass branch and a first grounding branch, the first bypass branch being connected in parallel with the inductive element and including two series-connected protective components of a first type and a bypass branch midpoint between them, where the first grounding branch is connected between the bypass branch midpoint and ground and includes a first grounding surge arrester.

Abstract: A multilevel converter cell includes a first section with a first group of series connected switching units in parallel with a first energy storage element, where a junction between a first and second switching units of the first group of series connected switching units forms one cell connection terminal, a second section with a second group of series connected switching units in parallel with a second energy storage element, where a junction between a third and fourth switching units of the second group of series connected switching units forms another cell connection terminal, and an interconnecting section with a third group of series-connected switching units comprising a fifth, sixth and seventh switching unit, with the fifth and sixth switching units connected in parallel with the first energy storage element and the sixth and seventh switching units connected in parallel with the second energy storage element.

Abstract: A multilevel converter cell includes a first section with a first group of series connected switching units in parallel with a first energy storage element, where a junction between a first and a second switching unit forms one cell connection terminal, a second section with a second group of series connected switching units in parallel with a second energy storage element, where a junction between a third and a fourth switching unit forms another cell connection terminal, and an interconnecting section with a third group of series-connected switching units comprising a fifth, sixth and seventh switching unit, with the fifth and sixth switching units connected in parallel with the first energy storage element and the sixth and seventh switching units connected in parallel with the second energy storage element.

Abstract: A method is provided for controlling a multilevel converter to balance voltages of submodule energy stores. This balancing involves calculating predicted final voltages of energy stores at the end of a time interval to follow and selecting which submodule of a phase arm to insert or bypass during the time interval based on a comparison of the predicted final voltages of the energy stores. The predicted final voltages are updated in accordance with any selection made of which submodule to insert or bypass during the time interval. A control device and a computer program product are also disclosed. Voltage balancing according to a pre-programmed modulation scheme is possible by means of the disclosed method.

Abstract: A method is provided for controlling a multilevel converter to balance voltages of submodule energy stores. This balancing involves calculating predicted final voltages of energy stores at the end of a time interval to follow and selecting which submodule of a phase arm to insert or bypass during the time interval based on a comparison of the predicted final voltages of the energy stores. The predicted final voltages are updated in accordance with any selection made of which submodule to insert or bypass during the time interval. A control device and a computer program product are also disclosed. Voltage balancing according to a pre-programmed modulation scheme is possible by means of the disclosed method.