An arrangement for exchanging power with a three-phase electric power network includes a Voltage Source Converter having three phase legs with each a series connection of switching cells. The three phase legs are interconnected in a neutral point by forming a wye-connection. The arrangement also includes a device connected to the neutral point of the converter and configured to provide a current path for a zero-sequence current. A control unit is configured to calculate a value for amplitude and phase position for a zero-sequence current for which, when added to said three phase legs upon generation of a negative-sequence current, the resulting energy stored in energy storing capacitors in each phase leg will be constant and to control semiconductor devices of said switching cells to add such a zero-sequence current to the currents of each phase leg of the converter.