Electric power transmission plant, including voltage source converter (VSC) with additional phase leg

摘要

A plant for transmitting electric power comprises an alternating voltage network (5) with at least one phase (6, 7, 8) and at least one VSC-converter (9) having at least one phase leg (10, 11, 12) with two current valves (13-18) connected in series, in which a point of said phase leg between the two current valves is connected to a phase of the alternating voltage network. The converter comprises at least one additional such phase leg (23) more than the number of the phases of the alternating voltage network, and means (22, 25) are arranged to enable disconnecting of a phase leg connected to the phase of the alternating voltage network for this phase and connecting a said additional phase leg to said point of said leg on that phase instead.