two sets a first set and a second set of stator windings the primary side of the transformer 321 is connected to the first set of stator windings via wires 322 and the second set of stator windings is connected to the input of converter 331 via wires 346 like in fig1 the output of the rectifier 310 and the output of the converter 331 are connected in parallel to an input of a hvdc transmission system 390 further similar devices and generators 340 can be connected to the hvdc transmission system via wires 392 and 394 in general the working principle and advantages of this embodiment are similar to those of the embodiment shown in fig1 however the converter 331 in this embodiment is connected to a second set of stator windings instead of a second set of transformer secondary windings as in fig1 accordingly the converter 331 generates control currents and or control voltages in the second set of stator windings such that the control system not shown of the converter 331 has to be designed accordingly in particular the suppression of harmonics is handled by the line filter 328 in this embodiment as the active converter 321 cannot influence the transformer 321 in this embodiment fig4 shows a.