Patent ID: 8847430

Claim:
A method to control the power flow in a meshed HVDC power transmission network comprising at least three HVDC converter stations interconnected in a first closed path by at least three transmission lines, a first DC power flow control device, which is series connected to a first of the at least three transmission lines, the first DC power flow control device comprising a first converter in series connection with the first transmission line and a second converter in shunt connection with the first transmission line, the method comprising the steps of: converting, by the second converter working as an inverter, DC power from the first transmission line into AC power; supplying, by the second converter, the first converter with said AC power; and injecting, by the first converter, an additional positive or negative DC voltage into the one transmission line based on the AC power supplied from the second converter for controlling the first transmission line so that the DC current distribution in the first closed path is balanced.