System for use in a direct-current meshed network comprising at least one mesh having at least one node between a first link, a second link and a third link, said network being capable of operating according to a number N 1 of operational states, each operational state of the network being defined on the basis of the sign of the electric current present in the first link, the sign of the electric current present in the second link, the sign of the electric current present in the third link and a voltage present between two of the links of the mesh, said system comprising: - A power flow control device comprising a first terminal (A), a second terminal (B) and a third terminal (C), said device comprising at least one controlled voltage source connected between two of its terminals, said controlled voltage source of the power flow control device having an intrinsic topology arranged to respond to a number N 0 of operational states of the network, N 0 being greater than or equal to 1 and less than N 1 , said system being characterised in that it comprises: - A first terminal to be connected to the first link, a second terminal to be connected to the second link and a third terminal to be connected to the third link, - A switching interface (ISW) interposed between said terminals of the system and said terminals of the device, said switching interface (ISW) comprising a number M of switches, M being greater than or equal to four and chosen taking into account the values of said number N 0 and said number N 1 , - A control unit (UC) configured to control the M switches of said switching interface (ISW) in order to connect each terminal (A, B, C) of said power flow control device to a separate terminal of the system and to respond to an operational state of the network. - A power flow control device comprising a first terminal (A), a second terminal (B) and a third terminal (C), said device comprising at least one controlled voltage source connected between two of its terminals, said controlled voltage source of the power flow control device having an intrinsic topology arranged to respond to a number N 0 of operational states of the network, N 0 being greater than or equal to 1 and less than N 1 , said system being characterised in that it comprises: - A first terminal to be connected to the first link, a second terminal to be connected to the second link and a third terminal to be connected to the third link, - A switching interface (ISW) interposed between said terminals of the system and said terminals of the device, said switching interface (ISW) comprising a number M of switches, M being greater than or equal to four and chosen taking into account the values of said number N 0 and said number N 1 , - A control unit (UC) configured to control the M switches of said switching interface (ISW) in order to connect each terminal (A, B, C) of said power flow control device to a separate terminal of the system and to respond to an operational state of the network. - A first terminal to be connected to the first link, a second terminal to be connected to the second link and a third terminal to be connected to the third link, - A switching interface (ISW) interposed between said terminals of the system and said terminals of the device, said switching interface (ISW) comprising a number M of switches, M being greater than or equal to four and chosen taking into account the values of said number N 0 and said number N 1 , - A control unit (UC) configured to control the M switches of said switching interface (ISW) in order to connect each terminal (A, B, C) of said power flow control device to a separate terminal of the system and to respond to an operational state of the network. <EOS>