Abstract:
An arrangement for tapping power from a DC power line to an AC power line includes power transfer modules between two DC potentials, each including a first branch with a string of converter cells in parallel with a second branch including a capacitor and being connected to an AC phase. There is at least one control unit that controls the arrangement considering one or more of a) distributing appropriate AC and DC voltages in converter output voltages of all series connected modules, b) maintaining/setting cell capacitor voltages in specific range and allowing boost mode operation, c) performing possible balancing of the introduced capacitor and d) employing an alternate approach of using passive filters to mitigate low order harmonics.
Abstract:
Embodiments disclose using a pairing or pairings of terminals in a DC power system including a plurality of terminals to implement power oscillation damping (POD), where the DC power system is connectable to at least one AC power system. The active and/or reactive power of the terminals in the pairing may be controlled or modulated in a similar manner such that no power imbalance in the DC power system is created. For example, POD may be implemented by means of active and/or reactive power modulation by pairing two terminals in the DC power system) such that their active and/or reactive powers are controlled or modulated in the same or substantially the same manner or identically but with the opposite sign.