Method for reconstruction of a plant for transmitting electric power as well as such a plant

• US 6,067,238 A
• Filed: 01/28/1999
• Issued: 05/23/2000
• Est. Priority Date: 06/12/1997
• Status: Expired due to Term

• Current Assignee: ABB AB (ABB Limited)
• Original Assignee: ABB AB (ABB Limited)
• Inventors: Hermansson, Lars, Halvarsson, Bruno
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/230,560
• Time in Patent Office: 481 Days
• Field of Search: 363/35, 363/37, 363/34, 363/65, 307/87, 307/82, 307/85
• US Class Current: 363/35
• CPC Class Codes: H02J 3/36 Arrangements for transfer of electric power between ac networks via a high-tension dc link
• CPC Class Codes: Y02E 60/60 Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

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.

Claims

1. A method for reconstruction of a plant for transmitting electric power, which comprises a direct voltage network for High Voltage Direct Current (HVDC) and two stations connected thereto with line commutated valves having thyristors as rectifying semiconductor components for transmitting electric power between the direct voltage network and alternating voltage networks connected to the respective station thereof, the reconstruction aiming at connecting such additional stations to the direct voltage network while enabling feeding of electric power in an optional direction in each of the stations with the respective valve either in a rectifying operation for feeding electric power from the alternating voltage network to the direct voltage transmission or with the valve in an inverter operation for feeding from the direct voltage network to the alternating voltage network, said method comprising the steps of replacing in one of said two stations the thyristors with bidirectionally controlled thyristors (BCT) with ability to conduct current therethrough in both directions and installing such thyristors as rectifying semiconductor components in the valves of each added station so as to enable a choice of power feeding direction from the direct voltage network to the respective alternating voltage network or from the respective alternating voltage network out on the direct voltage network in said one and each added station by controlling the current direction through the respective valve.

2. A method according to claim 1, wherein the plant is reconstructed by adding a further station to the two original ones.

3. A plant for transmitting electric power comprising a direct voltage network for High Voltage Direct Current (HVDC) and at least three stations connected thereto with line commutated valves having thyristors as rectifying semiconductor components for transmitting electric power between the direct voltage network and alternating voltage network connected to the stations, wherein at least all said stations except for one have bidirectionally controlled thyristors (BCT) as said rectifying thyristors adapted to optionally conduct current therethrough in one desired of two directions, and wherein the stations provided with bidirectionally controlled thyristors have an arrangement adapted to control said bidirectionally controlled thyristors to optionally determine the power feeding direction from the direct voltage network to the respective alternating voltage network or from the latter out on the direct voltage network through controlling the current direction through the valve of the station.

4. A plant according to claim 3, wherein one of the stations has thyristors with ability to only conduct current in one direction therethrough as said rectifying semiconductor components.

5. A plant according to claim 3, wherein the number of stations of the plant is three.