A power supporting arrangement for a power grid, said power supporting arrangement comprising: a first, second, third and fourth voltage source converter (14, 18, 30, 32), each one having a respective AC side and a respective DC side, a DC link interconnecting the DC sides of the first, second, third and fourth voltage source converters (14, 18, 30, 32), a first and a second switching arrangement (20, 34), each with a number of settable positions, a first synchronous machine, and a second synchronous machine, wherein: the AC side of the second voltage source converter is connected to the power grid and the first switching arrangement is connected between the first synchronous machine, the AC side of the first voltage source converter and the power grid, thereby making the first voltage source converter into a machine side converter and the second voltage source converter into a grid side converter, the AC side of the fourth voltage source converter is connected to the power grid and the second switching arrangement is connected between the second synchronous machine, the AC side of the third voltage source converter and the power grid, thereby making the third voltage source converter into a machine side converter and the fourth voltage source converter into a grid side converter, the first switching arrangement is operable to selectively connect the first synchronous machine to the power grid or to the AC side of the first voltage source converter, where the first synchronous machine is connected to the power grid in a first settable position of the first switching arrangement and to the AC side of the first voltage source converter in a second settable position of the first switching arrangement, and the second switching arrangement is operable to selectively connect the second synchronous machine to the power grid or to the AC side of the third voltage source converter, where the second synchronous machine is connected to the power grid in a first settable position of the second switching arrangement and to the AC side of the third voltage source converter in a second settable position of the second switching arrangement. a first, second, third and fourth voltage source converter (14, 18, 30, 32), each one having a respective AC side and a respective DC side, a DC link interconnecting the DC sides of the first, second, third and fourth voltage source converters (14, 18, 30, 32), a first and a second switching arrangement (20, 34), each with a number of settable positions, a first synchronous machine, and a second synchronous machine, the AC side of the second voltage source converter is connected to the power grid and the first switching arrangement is connected between the first synchronous machine, the AC side of the first voltage source converter and the power grid, thereby making the first voltage source converter into a machine side converter and the second voltage source converter into a grid side converter, the AC side of the fourth voltage source converter is connected to the power grid and the second switching arrangement is connected between the second synchronous machine, the AC side of the third voltage source converter and the power grid, thereby making the third voltage source converter into a machine side converter and the fourth voltage source converter into a grid side converter, the first switching arrangement is operable to selectively connect the first synchronous machine to the power grid or to the AC side of the first voltage source converter, where the first synchronous machine is connected to the power grid in a first settable position of the first switching arrangement and to the AC side of the first voltage source converter in a second settable position of the first switching arrangement, and the second switching arrangement is operable to selectively connect the second synchronous machine to the power grid or to the AC side of the third voltage source converter, where the second synchronous machine is connected to the power grid in a first settable position of the second switching arrangement and to the AC side of the third voltage source converter in a second settable position of the second switching arrangement.