Abstract: A power supporting arrangement for a power grid includes a first and a second voltage source converter with an AC side and a DC side. A DC link interconnects the DC sides of the voltage source converters. A first switching arrangement includes a number of settable positions. The AC side of the second voltage source converter is connected to the power grid and the first switching arrangement is connected between a first synchronous machine. The AC side of the first voltage source converter and the power grid and operable to selectively connect the first synchronous machine to the power grid or to the AC side of the first voltage source converter.

Abstract: An energy storage system and a method for controlling such a system is disclosed. The energy storage system comprises a plurality of interconnected energy storage cells forming an energy storage module, a power converter connected to the energy storage module, a resistor circuit connected in parallel to the energy storage module, a switch connected in series with the resistor circuit and configured to disconnect the resistor circuit from the energy storage module, and a control unit operably connected to the switch. The control unit is configured to receive information pertaining to a transmission of energy in the energy storage system and to control the switch based on said information.

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 power supporting arrangement for a power grid includes a first and a second voltage source converter with an AC side and a DC side. A DC link interconnects the DC sides of the voltage source converters. A first switching arrangement includes a number of settable positions. The AC side of the second voltage source converter is connected to the power grid and the first switching arrangement is connected between a first synchronous machine. The AC side of the first voltage source converter and the power grid and operable to selectively connect the first synchronous machine to the power grid or to the AC side of the first voltage source converter.

Abstract: A method of providing power support to an electrical power grid is provided. The power support is provided by an arrangement including a synchronous machine connected to a converter, the converter in turn being connected to the electrical power grid. The method is performed in a control device controlling the arrangement and includes: receiving feedback from one or both of the electrical power grid and the synchronous machine, and controlling the converter such that power support is provided to or absorbed from the electrical power grid by means of the synchronous machine based on the received feedback. A control device, arrangement, computer program and computer program products are also provided.

Abstract: A method of providing power support to an electrical power grid is provided. The power support is provided by an arrangement including a synchronous machine connected to a converter, the converter in turn being connected to the electrical power grid. The method is performed in a control device controlling the arrangement and includes: receiving feedback from one or both of the electrical power grid and the synchronous machine, and controlling the converter such that power support is provided to or absorbed from the electrical power grid by means of the synchronous machine based on the received feedback. A control device, arrangement, computer program and computer program products are also provided.

Abstract: The invention relates to methods and devices for controlling unbalanced active power flow in a three-phase modular multilevel converter 20. The converter 20 comprises a first and second converter 4, 5 both comprising three phase legs arranged in a wye-connection. The first and second converters 4, 5 are interconnected in a double-wye connection, and their neutral paths are independently floating.