Abstract: The invention relates to a power system that includes an electrical machine, (e.g., a motor or generator). The electrical machine has a stator with a stator winding connected to a power converter. The power system includes an assembly to reduce, and optionally eliminate, common mode currents between the electrical machine and the power converter. The assembly includes a stator frame connected to ground potential and an electrical insulator (e.g., a plurality of stator mounts) located between the stator frame and the stator.

Abstract: A power distribution system includes power converter systems electrically connected to a distribution bus which defines a point of common coupling. Each power converter system includes a power converter with semiconductor switching devices controlled using a pulse width modulation strategy with a switching frequency. A controller for each power converter system applies a spectrum analysis process to the respective power converter system that uses measured or derived zero sequence currents associated with the respective power converter system to determine the location of a ground fault within the power distribution system. Each controller applies a switching frequency process where the switching frequency of the power converter of at least one of the power converter systems is different from the switching frequency of the power converter of at least another one of the power converter systems during at least part of the time that the spectrum analysis process is applied.

Abstract: The invention relates to a power system that includes an electrical machine, (e.g., a motor or generator). The electrical machine has a stator with a stator winding connected to a power converter. The power system includes an assembly to reduce, and optionally eliminate, common mode currents between the electrical machine and the power converter. The assembly includes a stator frame connected to ground potential and an electrical insulator (e.g., a plurality of stator mounts) located between the stator frame and the stator.

Abstract: A power distribution system includes power converter systems electrically connected to a distribution bus which defines a point of common coupling. Each power converter system includes a power converter with semiconductor switching devices controlled using a pulse width modulation strategy with a switching frequency. A controller for each power converter system applies a spectrum analysis process to the respective power converter system that uses measured or derived zero sequence currents associated with the respective power converter system to determine the location of a ground fault within the power distribution system. Each controller applies a switching frequency process where the switching frequency of the power converter of at least one of the power converter systems is different from the switching frequency of the power converter of at least another one of the power converter systems during at least part of the time that the spectrum analysis process is applied.

Abstract: A power system for offshore application includes a plurality of power circuits. Each of the power circuit includes an alternating current (AC) bus which supplies power to an auxiliary load and is connected to a generator. The power circuit further includes a first direct current (DC) bus having a first DC voltage supplying power to a first load and a second DC bus having a second DC voltage supplying power to a second load. The power circuit also includes a first DC to DC converter coupled between the first DC bus and the second DC bus, wherein the first DC to DC converter is configured for bidirectional power flow and an AC to DC converter coupled between the AC bus and the first DC bus. The first DC bus of at least one power circuit is coupled to the second DC bus of at least another power circuit with a second DC to DC converter.

Abstract: A converter control arrangement (18) for regulating the output current of a dc source power converter (16) comprises a current regulator (20) for regulating the output current based on a comparison of an output current value (Iout) of the dc source power converter (16) with a desired target current value (Itgt). When the output voltage value (Vout) of the dc source power converter (16) is within a normal operating voltage range between minimum and maximum voltage values (Vmin, Vmax) defined with respect to a voltage reference value (Vref) of the dc source power converter (16), the converter control arrangement (18) controls the target current value (Itgt) so that it is equal to a desired reference current value (Iref).

Abstract: A power system for offshore application includes a plurality of power circuits. Each of the power circuit includes an alternating current (AC) bus which supplies power to an auxiliary load and is connected to a generator. The power circuit further includes a first direct current (DC) bus having a first DC voltage supplying power to a first load and a second DC bus having a second DC voltage supplying power to a second load. The power circuit also includes a first DC to DC converter coupled between the first DC bus and the second DC bus, wherein the first DC to DC converter is configured for bidirectional power flow and an AC to DC converter coupled between the AC bus and the first DC bus. The first DC bus of at least one power circuit is coupled to the second DC bus of at least another power circuit with a second DC to DC converter.

Abstract: The present invention relates to a vacuum switch assembly for interrupting and isolating fault current. The vacuum switch assembly includes first and second dc lines that, in use, are electrically connected to the dc output terminals of a primary dc power source and a dc network. Each dc line includes at least one vacuum switch having contacts that are opened and closed under the control of a vacuum switch controller. A passive dc power supply unit is electrically connected to the first and second dc lines and includes a secondary dc power source that provides a substantially ripple-free sensing voltage. The vacuum switch controller is adapted to open the vacuum switch contacts when a fault condition (e.g. a fault current or other fault) or an operator request has been identified and when the current flowing between the vacuum switch contacts is below a chopping current associated with the vacuum switches.

Abstract: A method of operating a power converter arrangement, the power converter arrangement includes a dc link and a dc load/source, an active rectifier/inverter having dc terminals connected to the dc link and is adapted to provide a variable dc link voltage between a maximum and a minimum limits, an interleaved buck converter having a plurality of converter circuits connected between the dc link and the dc load/source, wherein each converter circuit includes a first switch, a second switch, and a reactor, the method including determining one or more null values of dc link voltage with reference to the voltage across the dc load/source, and if a null value of dc link voltage is between the maximum and the minimum limits, controlling the active rectifier/inverter to provide a dc link voltage that is substantially the same as the null value of dc link voltage.

Abstract: A converter control arrangement (18) for regulating the output current of a dc source power converter (16) comprises a current regulator (20) for regulating the output current based on a comparison of an output current value (Iout) of the dc source power converter (16) with a desired target current value (Itgt). When the output voltage value (Vout) of the dc source power converter (16) is within a normal operating voltage range between minimum and maximum voltage values (Vmin, Vmax) defined with respect to a voltage reference value (Vref) of the dc source power converter (16), the converter control arrangement (18) controls the target current value (Itgt) so that it is equal to a desired reference current value (Iref).

Abstract: The present invention relates to a vacuum switch assembly for interrupting and isolating fault current. The vacuum switch assembly includes first and second dc lines that, in use, are electrically connected to the dc output terminals of a primary dc power source and a dc network. Each dc line includes at least one vacuum switch having contacts that are opened and closed under the control of a vacuum switch controller. A passive dc power supply unit is electrically connected to the first and second dc lines and includes a secondary dc power source that provides a substantially ripple-free sensing voltage. The vacuum switch controller is adapted to open the vacuum switch contacts when a fault condition (e.g. a fault current or other fault) or an operator request has been identified and when the current flowing between the vacuum switch contacts is below a chopping current associated with the vacuum switches.