Abstract: Embodiments disclose using a pairing or pairings of terminals in a DC power system including a plurality of terminals to implement power oscillation damping (POD), where the DC power system is connectable to at least one AC power system. The active and/or reactive power of the terminals in the pairing may be controlled or modulated in a similar manner such that no power imbalance in the DC power system is created. For example, POD may be implemented by means of active and/or reactive power modulation by pairing two terminals in the DC power system) such that their active and/or reactive powers are controlled or modulated in the same or substantially the same manner or identically but with the opposite sign.

Abstract: A multilevel current source converter (CSC) for controlling electrical power transmission in a high voltage direct current (HVDC) transmission system includes an alternating current (AC) side for input/output of AC to/from the CSC; a direct current (DC) side for input/output of DC to/from the CSC; and a plurality of modular CSC cells connected in parallel with each other between the AC side and the DC side of the CSC, each modular cell comprising a plurality of switches. The CSC is configured for being connected in series with an HVDC transmission line and for injecting a voltage in series with the HVDC transmission line at the DC side of the CSC.

Abstract: It is presented a DC/DC converter for converting power between a first DC connection comprising a first positive terminal and a first negative terminal, and a second DC connection comprising a second positive terminal and a second negative terminal. The DC/DC converter comprises: a first multilevel converter and a second multilevel converter connected serially between the first positive terminal and the first negative terminal, wherein the second positive terminal is connected to a point between the first multilevel converter and the second multilevel converter; and a first filter connected between an AC terminal of the first multilevel converter and an AC terminal of the second multilevel converter, wherein the first filter comprises a capacitor and an inductor.

Abstract: A method and system for controlling electrical power in a micro-grid, especially during islanding when the micro-grid is disconnected from a main grid is described. A potential load shedding for islanding is determined when the micro grid is connected to the main grid. The potential load shedding is performed when a grid switch that connects the micro-grid to a main grid opens. A frequency based load shedding and a frequency based control of power injections to the micro grid may also be performed. The frequency based load shedding is performed with a faster response than the power injection control during islanding. The frequency based power injection control is performed with a faster response than the frequency based load shedding when the micro grid is connected to the main grid. A load shedding controller, an energy storage controller and methods performed by the load shedding controller, and the energy storage controller, respectively, is also provided.

Abstract: A distributed method is provided for controlling electrical power in a microgrid, wherein a plurality of distributed generators supply electrical power to the microgrid, and each of the distributed generators is connected to a controller for controlling the real and reactive output power from the distributed generator.

Abstract: A microgrid connecting at least one distributed electricity generator includes a first switch configured for, in a closed position, connecting the microgrid to a first network line at a first point of common coupling (PCC) and for, in an open position, disconnecting the microgrid from the first network line at the first PCC; a second switch configured for, in a closed position, connecting the microgrid to a second network line at a second PCC, and for, in an open position, disconnecting the microgrid from the second network line at the second PCC; and a control unit configured for, when an islanding event has been detected when the second switch is in its closed position and the first switch is in its open position, acting to close the first switch, bringing it to its closed position.

Abstract: A high voltage valve arrangement includes a high voltage valve unit; an external electric shield structure arranged at least partially around the high voltage modular valve unit and a grounding system. The grounding system includes a grounding system configured to be remotely extended from a retracted position to an extended position, whereby the extendable grounding device establishes electric connection with the external shield structure when it is extended from the retracted position.

Abstract: A circuit breaking arrangement is disclosed, which is adapted to be coupled to a transmission line arranged to carry direct current for controllably effecting discontinuation of flow of direct current in the transmission line. The circuit breaking arrangement includes a current interrupter unit, which is adapted to, when actuated, interrupt current in the transmission line, and at least one resonance circuit. The resonance circuit is connected in parallel with the current interrupter unit and includes at least one capacitor, at least one inductor and at least one switch element. The resonance circuit is adapted to, upon actuation of the current interrupter unit, generate a resonance current superposing current of any arc generated in the current interrupter unit after actuation thereof, upon closing of the switch element by means of successive discharging and charging of the at least one capacitor.

Abstract: A photometer is provided for measuring the concentration of a chromophore in a fluid. The photometer includes a light source, a sample cell and a detector. The light source includes first, second, third and fourth light emitting diodes (LEDs). Each of the first and second LEDs emit light at a measurement wavelength and each of the third and fourth LEDs emit light at a reference wavelength. The first and second LEDs are arranged diagonal to each other and the third and fourth LEDs are arranged diagonal to each other. The photometer performs a routine for correcting concentration measurement for LED drift.

Abstract: A bundle of cables includes at least two underwater cables and a fastener for fastening the underwater cables together. The fastener is water-soluble, biologically decomposable and/or chemically decomposable. A method of laying at least two underwater cables simultaneously from a vessel and a method of using a water-soluble, biologically decomposable and/or chemically decomposable fastener to fasten at least two underwater cables together to form a bundle of cables are also described.

Abstract: It is presented a DC/DC converter for converting power between a first DC connection comprising a first positive terminal and a first negative terminal, and a second DC connection comprising a second positive terminal and a second negative terminal. The DC/DC converter comprises: a first multilevel converter and a second multilevel converter connected serially between the first positive terminal and the first negative terminal, wherein the second positive terminal is connected to a point between the first multilevel converter and the second multilevel converter; and a first filter connected between an AC terminal of the first multilevel converter and an AC terminal of the second multilevel converter, wherein the first filter comprises a capacitor and an inductor.

Abstract: A switch assembly including a vacuum switch mounted to an at least partly electrically conductive housing, and a holder for a vacuum bottle. The housing includes at least one gas entry opening at a lower end of the housing and at least one gas exit opening at an upper end of the housing, and a first free heat convection path between the openings to provide cooling. A second free heat convection path may be provided in a free space between the holder and vacuum bottle. A switching device for connecting the vacuum switch to a second electric conductor. An electric power distribution switchgear, encapsulating at least one three-phase module including a switching device.

Abstract: An electrical switchgear system includes a first compartment supplied with cooling air and in fluid communication with an exhaust plenum. A second compartment is in fluid communication with the exhaust plenum. A deflector is operative to deflect an amount of the cooling air from the first compartment and direct it into the second compartment. An electrical switchgear system having switchgear in an enclosure includes a first compartment disposed inside the enclosure and supplied with cooling air. A second compartment is disposed inside the enclosure. A deflector is operative to capture an amount of the cooling air from the first compartment and direct it into the second compartment.

Abstract: A unique electrical switchgear system may include a circuit breaker compartment having a compartment wall. The electrical switchgear system may also include a tapered floor pan mounted on the compartment wall. The floor pan may have two side walls disposed oblique to each other; a back wall; and a top wall coupled to the side walls and defining a discharge opening adjacent to the back wall. The two side walls, the top wall and the compartment wall may form a tunnel for channeling cooling air in a first direction. The back wall may be operative to redirect the cooling air in a second direction different from the first direction for discharging the cooling air from the discharge opening.

Abstract: A method of manufacturing a polymer-insulated conductor. The method includes the steps of a) providing a conductor having a first cross-sectional shape, b) passing the conductor through a conductor-shaping die to shape the conductor such that the conductor obtains a second cross-sectional shape, wherein frictional heat is developed in the conductor, thereby setting the conductor in a heated state, c) applying molten polymer to the conductor when the conductor is in the heated state to obtain a polymer-coated conductor, and d) shaping the polymer-coated conductor by means of a polymer-shaping die to thereby obtain the polymer-insulated conductor.

Abstract: Embodiments disclose using a pairing or pairings of terminals in a DC power system including a plurality of terminals to implement power oscillation damping (POD), where the DC power system is connectable to at least one AC power system. The active and/or reactive power of the terminals in the pairing may be controlled or modulated in a similar manner such that no power imbalance in the DC power system is created. For example, POD may be implemented by means of active and/or reactive power modulation by pairing two terminals in the DC power system) such that their active and/or reactive powers are controlled or modulated in the same or substantially the same manner or identically but with the opposite sign.

Abstract: A multilevel current source converter (CSC) for controlling electrical power transmission in a high voltage direct current (HVDC) transmission system includes an alternating current (AC) side for input/output of AC to/from the CSC; a direct current (DC) side for input/output of DC to/from the CSC; and a plurality of modular CSC cells connected in parallel with each other between the AC side and the DC side of the CSC, each modular cell comprising a plurality of switches. The CSC is configured for being connected in series with an HVDC transmission line and for injecting a voltage in series with the HVDC transmission line at the DC side of the CSC.