DC power transmission systems and method of assembling the same

Patent metadata

Field	Value
Publication number	US-9419536-B2
Application number	US-201414193525-A
Country	US
Kind code	B2
Filing date	Feb 28, 2014
Priority date	Feb 28, 2014
Publication date	Aug 16, 2016
Grant date	Aug 16, 2016

Abstract

A DC power transmission system is configured to generate an electric field including components substantially constant with respect to time and varying with time. The DC power transmission system includes an AC stage configured to receive AC electrical power. The AC stage includes a transformer including primary windings and secondary windings configured to be electromagnetically coupled to, and electrically isolated from, each other. The AC stage also includes an AC/AC converter having substantially no insulating features against the at least one substantially constant component of the electric field. The AC/AC converter is electrically coupled to the primary windings. The DC power transmission system also includes an AC/DC conversion stage positioned downstream of the AC stage. The AC/DC conversion stage includes an AC/DC rectifier configured to convert AC electrical power to DC electrical power without external control. The AC/DC rectifier is coupled to the secondary windings.

First claim

What is claimed is:

1. A direct current (DC) power transmission system configured to generate a DC electric field component and an alternating current electric field component, said DC power transmission system comprising:
an alternating current (AC) stage configured to receive AC electrical power, said AC stage comprising:
a transformer comprising primary windings and secondary windings configured to be electromagnetically coupled to each other and electrically isolated from each other;
an AC/AC converter having substantially no insulating features against the DC electric field component and being electrically coupled to at least one primary winding of said primary windings;
an AC/DC conversion stage positioned downstream of said AC stage, said AC/DC conversion stage comprising an AC/DC rectifier configured to convert AC electrical power to DC electrical power without external control, said AC/DC rectifier coupled to at least one secondary winding of said secondary windings;
wherein said AC/AC converter comprises a plurality of parallel AC/AC converters; and
wherein said AC/DC rectifier comprises a plurality of series AC/DC rectifiers positioned downstream of said plurality of parallel AC/AC converters.

2. The DC power transmission system in accordance with claim 1 , wherein said AC/AC converter and said AC/DC rectifier at least partially form a power conversion section, said power conversion section comprises at least one disabling device configured to selectively disable at least a portion of said power conversion section.

3. The DC power transmission system in accordance with claim 2 , wherein said at least one disabling device comprises at least one of:
a disable switch coupled in series with said at least one AC/AC converter; and
a grounding switch coupled to said at least one AC/AC converter.

4. The DC power transmission system in accordance with claim 1 , wherein said at least one AC/DC conversion stage further comprises a controllable switch that facilitates current transmission from a terminal having a positive polarity to a terminal having a negative polarity.

5. The DC power transmission system in accordance with claim 4 , wherein said controllable switch comprises a thyristor.

6. The DC power transmission system in accordance with claim 1 , wherein the AC electrical power is transmitted from an AC power grid having an AC power grid frequency, said AC/AC converter is configured to increase the frequency of the AC electrical power from the AC power grid.

7. The DC power transmission system in accordance with claim 1 , wherein the AC electrical power is transmitted from an AC power grid having an AC power grid frequency, said transformer is configured to operate with a fundamental frequency that is different from the AC power grid frequency.

8. The DC power transmission system in accordance with claim 1 , wherein said AC stage further comprises a switch coupled in parallel with said AC/AC converter, wherein said switch is selectively controlled to at least one of increase and decrease a transmission voltage level of said AC stage.

9. The DC power transmission system in accordance with claim 8 , wherein said switch facilitates coarse control of the transmission voltage and said AC/AC converter facilitates fine control of the transmission voltage.

10. The DC power transmission system in accordance with claim 1 , wherein said AC/DC conversion stage further comprises a filtering component positioned downstream of said AC/DC rectifier, said filtering component configured to facilitate reducing at least one of DC ripple and AC harmonics on the DC electrical power.

11. The DC power transmission system in accordance with claim 1 , wherein said AC/DC rectifier comprises a diode configured to attain a stable short circuit condition.

12. A transmission end converter for a DC transmission system, said transmission end converter configured to generate a DC electric field component and an alternating current electric field component, said transmission end converter comprising:
an alternating current (AC) stage configured to receive AC electrical power, said AC stage comprising:
a transformer comprising primary windings and secondary windings configured to be electromagnetically coupled to each other and electrically isolated from each other;
an AC/AC converter having substantially no insulating features against the DC electric field component and being electrically coupled to at least one primary winding of said primary windings;
an AC/DC conversion stage positioned downstream of said AC stage, said AC/DC conversion stage comprising a AC/DC rectifier configured to convert AC electrical power to DC electrical power without external control, said AC/DC rectifier coupled to at least one secondary winding of said secondary windings;
wherein said AC/AC converter comprises a plurality of parallel AC/AC converters; and
wherein said AC/DC rectifier comprises a plurality of series AC/DC rectifiers positioned downstream of said plurality of parallel AC/AC converters.

13. The transmission end converter in accordance with claim 12 , wherein said AC/AC converter and said AC/DC rectifier at least partially form a power conversion section, said power conversion section comprises a disabling device configured to selectively disable at least a portion of said power conversion section.

14. The transmission end converter in accordance with claim 13 , wherein said disabling device comprises at least one of:
a disable switch coupled in series with said AC/AC converter; and
a grounding switch coupled to said AC/AC converter.

15. The transmission end converter in accordance with claim 12 , wherein said AC/DC conversion stage further comprises a controllable switch that facilitates current transmission from a terminal having a positive polarity to a terminal having a negative polarity.

16. The transmission end converter in accordance with claim 15 , wherein said controllable switch comprises a thyristor.

17. The transmission end converter in accordance with claim 12 , wherein the AC electrical power is transmitted from an AC power grid having an AC power grid frequency, said AC/AC converter is configured to increase the frequency of the AC electrical power from the AC power grid.

18. The transmission end converter in accordance with claim 12 , wherein the AC electrical power is transmitted from an AC power grid having an AC power grid frequency, said transformer is configured to operate with a fundamental frequency that is different from the AC power grid frequency.

19. The transmission end converter in accordance with claim 12 , wherein said AC stage further comprises a switch coupled in parallel with said AC/AC converter, wherein said switch is selectively controlled to at least one of increase and decrease a transmission voltage level of said AC stage.

20. The transmission end converter in accordance with claim 19 , wherein said switch facilitates coarse control of the transmission voltage and said AC/AC converter facilitates fine control of the transmission voltage.

21. The transmission end converter in accordance with claim 12 , wherein said AC/DC conversion stage further comprises a filtering component positioned downstream of said AC/DC rectifier, said filtering component configured to facilitate reducing at least one of DC ripple and AC harmonics on the DC electrical power.

22. The transmission end converter in accordance with claim 12 , wherein said AC/DC rectifier comprises a diode con

Assignees

• Gen Electric

Inventors

• Wijekoon Piniwan Thiwanka Bandara
• Sihler Christof Martin
• Schroeder Stefan
• Shen Jie
• Tenca Pierluigi

Classifications

• Y02E60/60

  Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD] · CPC title

• H02M1/12

  Arrangements for reducing harmonics from AC input or output · CPC title

• H02M7/06 Primary

  using discharge tubes without control electrode or semiconductor devices without control electrode · CPC title

• H02M5/04

  by static converters (controlling transformers, reactors or choke coils, e.g. by tap changing H02P13/00) · CPC title

• H02J3/36 Primary

  Arrangements for transfer of electric power between AC networks via high-voltage DC [HVDC] links; Arrangements for transfer of electric power between generators and networks via HVDC links · CPC title