Abstract: Embodiments of the present disclosure relate to an uninterruptible power supply. The uninterruptible power supply comprises a switch, a power management module, an inverter and a controller. The switch is arranged between a load and a power source, the power source configured to supply power to the load. The power management module comprises a main energy storage and configured to reduce a ripple experienced by the main energy storage. The inverter is arranged between and coupled to the power management module and the load. The controller is coupled to the power management module, the inverter and the switch, the controller configured to control the inverter to regulate output voltage magnitude and frequency by regulating the power exchange between the inverter and the power source. According to embodiments of the present disclosure, the overcharging of the energy storage during sudden load rejections or utility phase jumps can be avoided.

Abstract: A method of regulating frequency of plurality of uninterruptible power supply units and corresponding uninterruptible power supply (UPS) unit. The method includes broadcasting, to a controller of a UPS unit, an expected synchronization direction to other UPS units via a communication link, the expected synchronization direction being determined based on a frequency of the corresponding UPS units and a frequency of a grid. The method includes obtaining the expected synchronization directions of other UPS units via the communication link; determining a major synchronization direction based on the expected synchronization direction of each UPS unit; and regulating a frequency of each UPS unit based on the major synchronization direction.

Abstract: Embodiments of the present disclosure relate to an uninterruptible power supply. The uninterruptible power supply comprises a switch, a power management module, an inverter and a controller. The switch is arranged between a load and a power source, the power source configured to supply power to the load. The power management module comprises a main energy storage and configured to reduce a ripple experienced by the main energy storage. The inverter is arranged between and coupled to the power management module and the load. The controller is coupled to the power management module, the inverter and the switch, the controller configured to control the inverter to regulate output voltage magnitude and frequency by regulating the power exchange between the inverter and the power source. According to embodiments of the present disclosure, the overcharging of the energy storage during sudden load rejections or utility phase jumps can be avoided.

Abstract: A method of regulating frequency of plurality of uninterruptible power supply units and corresponding uninterruptible power supply (UPS) unit. The method includes broadcasting, to a controller of a UPS unit, an expected synchronization direction to other UPS units via a communication link, the expected synchronization direction being determined based on a frequency of the corresponding UPS units and a frequency of a grid. The method includes obtaining the expected synchronization directions of other UPS units via the communication link; determining a major synchronization direction based on the expected synchronization direction of each UPS unit; and regulating a frequency of each UPS unit based on the major synchronization direction.

Abstract: Embodiments of the present disclosure relate to method and apparatus for detecting grid islanding in a grid supporting voltage source converter. The method includes modulating an output voltage at an output of the grid supporting voltage source converter; determining at least one grid parameter at an input to the grid supporting voltage source converter; and detecting the grid islanding for the grid supporting voltage source converter based on the at least one grid parameter.

Abstract: Embodiments of the present disclosure relate to parallel 3-level inverter without midpoint connection. The parallel 3-level inverter includes a plurality of parallel converters coupled in parallel between a common DC bus and a common AC output, wherein each of the plurality of parallel converters comprises a midpoint and the midpoints of the plurality of parallel converters are disconnected from each other.

Abstract: Embodiments of present disclosure relate to apparatus and method for flux management in the ZISC based UPS system. The apparatus comprises: a first determining unit configured to determine a first offset flux on a series reactor in the ZISC based UPS system when power quality events occur in a grid connected to the ZISC based UPS system and the ZISC based UPS system operates in a grid-connected mode; and a first resetting unit configured to provide synthetic impedance damping to the series reactor to reset the first offset flux.

Abstract: Embodiments of the present disclosure relate to an uninterruptible power supply. The uninterruptible power supply comprises a switch, a power management module, an inverter and a controller. The switch is arranged between a load and a power source, the power source configured to supply power to the load. The power management module comprises a main energy storage and configured to reduce a ripple experienced by the main energy storage. The inverter is arranged between and coupled to the power management module and the load. The controller is coupled to the power management module, the inverter and the switch, the controller configured to control the inverter to regulate output voltage magnitude and frequency by regulating the power exchange between the inverter and the power source. According to embodiments of the present disclosure, the overcharging of the energy storage during sudden load rejections or utility phase jumps can be avoided.

Abstract: Embodiments of the present disclosure relate to parallel 3-level inverter without midpoint connection. The parallel 3-level inverter includes a plurality of parallel converters coupled in parallel between a common DC bus and a common AC output, wherein each of the plurality of parallel converters comprises a midpoint and the midpoints of the plurality of parallel converters are disconnected from each other.

Abstract: Embodiments of the present disclosure provide an electrical apparatus, a power supply system having the same and a method of manufacturing the electrical apparatus. The electrical apparatus includes a detecting circuit coupled to a generator and configured to detect a frequency of the generator. The electrical apparatus also includes a controller coupled to the detecting circuit and configured to receive a first signal indicating the detected frequency and adjust the frequency of the generator in response to determining that the detected frequency is out of a predetermined frequency range. In this way, an actively controlling of the changing rate of the power to and from generator may be achieved, if the generator frequency exceeds the configured limits.

Abstract: Embodiments of present disclosure relate to apparatus and method for flux management in the ZISC based UPS system. The apparatus comprises: a first determining unit configured to determine a first offset flux on a series reactor in the ZISC based UPS system when power quality events occur in a grid connected to the ZISC based UPS system and the ZISC based UPS system operates in a grid-connected mode; and a first resetting unit configured to provide synthetic impedance damping to the series reactor to reset the first offset flux.

Abstract: Embodiments of the present disclosure relate to method and apparatus for detecting grid islanding in a grid supporting voltage source converter. The method includes modulating an output voltage at an output of the grid supporting voltage source converter; determining at least one grid parameter at an input to the grid supporting voltage source converter; and detecting the grid islanding for the grid supporting voltage source converter based on the at least one grid parameter.

Abstract: Embodiments of the present disclosure provide an electrical apparatus, a power supply system having the same and a method of manufacturing the electrical apparatus. The electrical apparatus includes a detecting circuit coupled to a generator and configured to detect a frequency of the generator. The electrical apparatus also includes a controller coupled to the detecting circuit and configured to receive a first signal indicating the detected frequency and adjust the frequency of the generator in response to determining that the detected frequency is out of a predetermined frequency range. In this way, an actively controlling of the changing rate of the power to and from generator may be achieved, if the generator frequency exceeds the configured limits.

Abstract: A method of controlling a power converter, connected to an electrical grid, to mimic a synchronous generator, by: determining a frequency control error with respect to a setpoint and actual frequency of the grid, determining an input power to an inertia model of a synchronous generator based on the frequency control error, regulating by means of the input power a rotational frequency of the inertia model, determining a voltage control error with respect to a setpoint and actual voltage, determining an exciter parameter of a synchronous generator model based on the voltage control error, regulating by means of the exciter parameter an output voltage of the synchronous generator model, adjusting the rotational frequency or a phase angle obtained from the rotational frequency, and the output voltage based on a virtual impedance of a stator of the synchronous generator model, and controlling the power converter based on the adjusted rotational frequency or the adjusted phase angle and on the adjusted output volta

Abstract: One embodiment is a uninterruptable power supply (UPS) system including a utility disconnect switch (UDS) coupled with an input line and an output line and structured to selectably connect and disconnect the input line and the output line. The UDS includes a semiconductor switching device connected between the input line and the output line, a surge arrester coupled in parallel with the semiconductor switching device, a dynamic voltage balancing device and a static voltage balancing device which are coupled in parallel with the semiconductor switching device.

Abstract: A method of controlling a power converter, connected to an electrical grid, to mimic a synchronous generator, by: determining a frequency control error with respect to a setpoint and actual frequency of the grid, determining an input power to an inertia model of a synchronous generator based on the frequency control error, regulating by means of the input power a rotational frequency of the inertia model, determining a voltage control error with respect to a setpoint and actual voltage, determining an exciter parameter of a synchronous generator model based on the voltage control error, regulating by means of the exciter parameter an output voltage of the synchronous generator model, adjusting the rotational frequency or a phase angle obtained from the rotational frequency, and the output voltage based on a virtual impedance of a stator of the synchronous generator model, and controlling the power converter based on the adjusted rotational frequency or the adjusted phase angle and on the adjusted output volta

Abstract: One embodiment is a uninterruptable power supply (UPS) system including a utility disconnect switch (UDS) coupled with an input line and an output line and structured to selectably connect and disconnect the input line and the output line. The UDS includes a semiconductor switching device connected between the input line and the output line, a surge arrester coupled in parallel with the semiconductor switching device, a dynamic voltage balancing device and a static voltage balancing device which are coupled in parallel with the semiconductor switching device.