Abstract: A plant for transmitting electric power with a direct voltage network and at least two stations connected thereto with line commutated valves (15, 16) with bidirectionally controlled thyristors (BCT) with ability to conduct current in both directions therethrough as rectifying semiconductor components, comprises at least one cable (12) with an insulating mantle with a polymer base surrounding the conductor thereof for forming the direct voltage network interconnecting the stations. The plant has also a unit (21) adapted to control the thyristors of the valves for changing the power feeding direction between the stations through changing the current direction in said cable.

Abstract: A plant for transmitting electric power with a direct voltage network and at least two stations connected thereto with line commutated valves (15, 16) with bidirectionally controlled thyristors (BCT) with ability to conduct current in both directions therethrough as rectifying semiconductor components, comprises at least one cable (12) with an insulating mantle with a polymer base surrounding the conductor thereof for forming the direct voltage network interconnecting the stations. The plant has also a unit (21) adapted to control the thyristors of the valves for changing the power feeding direction between the stations through changing the current direction in said cable.

Abstract: In a plant for transmitting electric power between two stations (17, 18) through a direct voltage network (16) for High Voltage Direct Current an arrangement (23) is arranged for draining electric power from the direct voltage network. The arrangement has a valve (24) made of bidirectionally controlled thyristors (BCT) with ability to conduct current in both directions therethrough. The plant has also a unit (25) adapted to control the thyristors of the valve so that the current direction between the direct voltage network and the valve is such that electric power is fed from the direct voltage network to an alternating voltage network- connected to the valve independently of the power feeding direction between said two stations (17, 18).

Abstract: A plant for transmitting electric power having a direct voltage network (18) for High Voltage Direct Current and at least one pole conductor interconnecting two stations (21, 22). In each station (21, 22), a bidirectionally controlled thyristor (BCT) conducts current in both directions as rectifying semiconductor components. A control unit (35) is adapted to control the current direction through the bidirectionally controlled thyristors so as to choose that the earth electrode (33, 34) of each station is always either anode or cathode.

Abstract: An HVDC-plant with two stations with line commutated valves having tyristors, as rectifying semiconductor components for transmitting electric power between a direct voltage network and alternating voltage networks connected to the stations thereof is reconstructed by adding further stations thereto. In one of the two stations, the thyristors are replaced by bidirectionally controlled thyristors with ability to conduct current therethrough in both directions, and such tyristors are also arranged in the valves of each added station so as to provide an option of power feeding direction from the direct voltage network to the connected alternating voltage network of the respective station or from the respective connected alternating voltage network out to the direct voltage network in the one or each added station by controlling the current direction through the respective valve.