Control for power plant

• US 6,411,529 B1
• Filed: 01/17/2001
• Issued: 06/25/2002
• Est. Priority Date: 05/19/1999
• Status: Expired due to Fees

• Current Assignee: ABB AB (ABB Limited), Intel Corporation
• Original Assignee: ABB AB (ABB Limited)
• Inventors: Svensson, Kjell
• Primary Examiner(s): Riley, Shawn
• Application Number:
  US09/743,853
• Time in Patent Office: 524 Days
• Field of Search: 363/35, 363/129, 363/125, 363/127, 363/128, 363/51, 363/54, 363/53, 361/101, 323/908
• US Class Current: 363/35
• CPC Class Codes: H02M 7/757 using semiconductor devices only
• 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

A plant for transmitting electric power which employs a first combination of a turn off semiconductor and controllable semiconductor connected in antiparallel and a second combination of a turn off semiconductor and antiparallel wherein the first combination is alternately conducting and blocking current for producing an alternating current output and the second combination is conducting during normal operation of the plant. When a fault occurs, a disconnect switch opens and separates the plant from other plants located on the network.

Claims

1. A plant for transmitting electric power comprising a first power semiconductor device having conducting and non-conducting states and being connected in series with a conductor and a second power semiconductor device having conducting and non-conducting states, connected in anti-parallel therewith and being able to assume the non-conducting state in which it blocks conduction of current therethrough when voltage is applied to the first power semiconductor device in a conducting direction thereof and being able to assume the conducting state in which it conducts current therethrough when voltage is applied over the first power semiconductor device in a direction opposite to the conducting direction, said first semiconducting device comprising a turn-off type power source and the second semiconducting device comprising a controllable device having a conducting direction opposite to that of said first power semiconductor device;

a switch wherein the first power semiconductor device is operable to conduct current during normal function of the plant and operable to be turned off for fulfilling a dis-connector function when desired, said switch is arranged in a network for transmitting high voltage direct current (HVDC) for safety disconnection upon occurrence of a fault, the switch being arranged proximate to a converter associated with a first station for converting direct voltage into alternating voltage conversely comprising an arrangement adapted to control a change of state of the second power semiconductor device to the blocking state for preventing feeding of current towards the converter when desired, and at least one converter of a second state being connected in parallel with said proximate converter, said converters belonging to different stations of a multiple station system having direct voltage networks connected in a meshed fashion.

2. The plant according to claim 1, when said arrangement is adapted to cause said change of state in response to occurrence of a fault.

3. The plant according to claim 1 comprising a VSC-converter for converting direct voltage into alternating voltage or direct voltage and conversely and which has at least one phase leg with two current valves, each having an end and being connected in series, and in which a point of the phase leg between said connected valves is intended to be connectable to a phase of a direct voltage or alternating voltage network and the ends of the phase leg are connectable to a pole conductor each of a direct voltage network wherein the valves comprise at least one additional semiconductor device and at least one additional second power semiconductor device connected in anti-parallel therewith.

4. The plant according to claim 3, wherein the converter comprises a two level converter.

5. The plant according to claim 3, wherein the converter comprises an NPC-converter.

6. The plant according to claim 3, further comprising an arrangement adapted to control the turning on of the additional second power semiconductor device when a voltage is applied to the converter and by an increase in the voltage applied on the direct voltage side.

7. The plant according to claim 3, wherein the second power semiconductor device is adapted to be in the conducting state during normal operation of the plant.

8. The plant according to claim 3, further comprising an arrangement adapted to control the first and the second power semiconductor device through a light conductor in common through coded orders.

9. The plant according to claim 1, further comprising an arrangement adapted to control first power semiconductor device and the second power semiconductor device simultaneously through one and the same order.

10. The plant according to claim 1, further comprising a plurality of first power semiconductor devices connected in series and a plurality of second power semiconductor devices connected in series connected in anti-parallel therewith.

11. The plant according to claim 1, wherein the controllable second power semiconductor device comprises a thyristor.

12. The plant according to claim 1, wherein the second power semiconductor device comprises an IGBT.

13. The plant according to claim 1, wherein the controllable second power semiconductor device comprises a gate turn off.

14. The plant according to claim 1, wherein the first power semiconductor device comprises an IGBT.

15. The plant according to claim 1, wherein the first power semiconductor device comprises a gate turn off thyristor.