Abstract: An apparatus and a method for filtering harmonics in a power transmission contact line of a railway system includes a multilevel converter multilevel converter having one single phase leg, which phase leg comprises switching cells, each switching cell comprises semi-conductor switches arranged to selectively provide a connection to a corresponding energy storage element. The multilevel converter also includes a controller provided to control the switching of each switching cell, and wherein the phase leg is configured in two parallel branches of cascaded switching cells, which branches is interconnected in a closed circuit. The controller is provided to monitor the content of harmonics in the contact line, and is adapted to filter the monitored harmonics by means of adapting the switching of the switching cells to absorb the harmonics.

Abstract: A method in a controller for protection of a voltage source converter including one or more phases, each phase including one or more series-connected converter cells. Each converter cell has a by-pass switch for enabling by-pass thereof. The method includes the steps of detecting an over-voltage condition, and controlling simultaneously the by-pass switches of each converter cell, so as to bypass the converter cells upon detection of such over-voltage condition. The invention also encompasses a controller, computer programs and computer program products.

Abstract: A multilevel converter for controlling a multilevel converter is provided. The multilevel converter is a single phase converter with one phase leg, or a three phase converter with three phase legs, the phase legs of the three phase converter are interconnected in a star-configuration. The single phase converter with one phase leg, or each three phase converter with three phase legs, phase leg includes switching cells, and each switching cell includes semi-conductor switches arranged to selectively provide a connection to a corresponding energy storage element. The converter also includes a controller, which is provided to monitor the DC voltage of the energy storage elements, and the controller is provided to control the switching of each switching cell. The phase leg of the single phase converter, or each phase leg of the three phase converter, includes two parallel branches of switching cells, the branches being configured in a closed circuit.

Abstract: A housing for a power semiconductor, providing a compartment for installation of a power semiconductor, and including a first and a second terminal. The terminals are for connection of a power semiconductor installed in the compartment, and for leading current to and from the compartment. The housing includes a contact mechanism for bypassing the compartment, the contact mechanism including at least one movable contact arranged for electrically connecting the first and second terminal, the at least one movable contact being movable between a disconnected first position and a connected second position. The contact mechanism further includes a bypass actuator arranged inside the compartment and provided for transforming a pressure from an exploding semiconductor into motion, the bypass actuator is operatively connected to the movable contact and arranged to move the movable contact from the first to the second position when subjected to the pressure of an exploding semiconductor.

Abstract: A method of controlling a magnitude of an electrical parameter in a power system via a high voltage electron tube. The method includes the steps of measuring the magnitude of the electrical parameter; generating a control signal based on the magnitude of the electrical parameter and on a reference magnitude of the electrical parameter; and switching the high voltage electron tube via the control signal such that the reference magnitude of the electrical parameter is essentially obtained. A control arrangement and a power system is also presented.

Abstract: A multilevel converter for controlling a multilevel converter is provided. The multilevel converter is a single phase converter with one phase leg, or a three phase converter with three phase legs, the phase legs of the three phase converter are interconnected in a star-configuration. The single phase converter with one phase leg, or each three phase converter with three phase legs, phase leg includes switching cells, and each switching cell includes semi-conductor switches arranged to selectively provide a connection to a corresponding energy storage element. The converter also includes a controller, which is provided to monitor the DC voltage of the energy storage elements, and the controller is provided to control the switching of each switching cell. The phase leg of the single phase converter, or each phase leg of the three phase converter, includes two parallel branches of switching cells, the branches being configured in a closed circuit.

Abstract: A housing for a power semiconductor, providing a compartment for installation of a power semiconductor, and including a first and a second terminal. The terminals are for connection of a power semiconductor installed in the compartment, and for leading current to and from the compartment. The housing includes a contact mechanism for bypassing the compartment, the contact mechanism including at least one movable contact arranged for electrically connecting the first and second terminal, the at least one movable contact being movable between a disconnected first position and a connected second position. The contact mechanism further includes a bypass actuator arranged inside the compartment and provided for transforming a pressure from an exploding semiconductor into motion, the bypass actuator is operatively connected to the movable contact and arranged to move the movable contact from the first to the second position when subjected to the pressure of an exploding semiconductor.

Abstract: A method in a controller for protection of a voltage source converter including one or more phases, each phase including one or more series-connected converter cells. Each converter cell has a by-pass switch for enabling by-pass thereof. The method includes the steps of detecting an over-voltage condition, and controlling simultaneously the by-pass switches of each converter cell, so as to bypass the converter cells upon detection of such over-voltage condition. The invention also encompasses a controller, computer programs and computer program products.

Abstract: A method of controlling a magnitude of an electrical parameter in a power system via a high voltage electron tube. The method includes the steps of measuring the magnitude of the electrical parameter; generating a control signal based on the magnitude of the electrical parameter and on a reference magnitude of the electrical parameter; and switching the high voltage electron tube via the control signal such that the reference magnitude of the electrical parameter is essentially obtained. A control arrangement and a power system is also presented.

Abstract: A voltage source converter having a plurality of cell modules connected in series, each cell module including a converter unit having an ac-side and a dc-side, and the voltage source converter includes a control unit adapted to control the converter units, where at least one of the cell modules includes a second redundant converter unit having an ac-side which is connected in parallel with the ac-side of the first converter unit and the control unit is configured to substantially synchronously control the first and the second converter units.

Abstract: Voltage source converter based on a chain-link cell topology including one or more phases, each of the phases having one or more series-connected chain-link cell modules connected to each other. The output voltage of the voltage source converter is controlled by control signals applied to the series-connected chain-link cell modules. In case of failure of a chain-link cell module, that module is controlled, by the control signals, such that zero output voltage is provided at its output voltage AC terminal.

Abstract: A voltage source converter having a plurality of cell modules connected in series, each cell module including a converter unit having an ac-side and a dc-side, and the voltage source converter includes a control unit adapted to control the converter units, where at least one of the cell modules includes a second redundant converter unit having an ac-side which is connected in parallel with the ac-side of the first converter unit and the control unit is configured to substantially synchronously control the first and the second converter units.

Abstract: An arrangement to determine a cell capacitor voltage value of a cell of a multi-cell power converter includes the cell and a control unit. The cell itself includes four power electronic valves interconnected as a full-bridge converter having a first and a second phase leg, where each phase leg includes a series-connection of two of the four power electronic valves and where the connection point between the two power electronic valves of each phase leg is externally connectable, a cell capacitor being connected in parallel to the first and the second phase legs, and four gate units, each being connected to a corresponding one of the power electronic valves as well as to the control unit.

Abstract: Power exchanging arrangement, in shunt connection, with a three-phase electric power network including on one hand for each said phase a reactive impedance element and a Voltage Source Converter connected in series with said element, and on the other hand a control unit configured to control semiconductor devices of turn-off type of said converter for generating a voltage with a fundamental frequency being equal to the fundamental frequency of the voltage of the respective said phase and by that control a flow of reactive power between said arrangement and the respective phase of said electric power network. Each Voltage Source Converter includes a series connection of switching cells in the form of so-called H-bridges including two switching elements connected in parallel and each having at least two semiconductor assemblies connected in series. Each switching cell further comprises at least one energy storing capacitor connected in parallel with said switching elements.

Abstract: Voltage source converter based on a chain-link cell topology including one or more phases, each of the phases having one or more series-connected chain-link cell modules connected to each other. The output voltage of the voltage source converter is controlled by control signals applied to the series-connected chain-link cell modules. In case of failure of a chain-link cell module, that module is controlled, by the control signals, such that zero output voltage is provided at its output voltage AC terminal.

Abstract: An arrangement to determine a cell capacitor voltage value of a cell of a multi-cell power converter includes the cell and a control unit. The cell itself includes four power electronic valves interconnected as a full-bridge converter having a first and a second phase leg, where each phase leg includes a series-connection of two of the four power electronic valves and where the connection point between the two power electronic valves of each phase leg is externally connectable, a cell capacitor being connected in parallel to the first and the second phase legs, and four gate units, each being connected to a corresponding one of the power electronic valves as well as to the control unit.