Apparatus for electrical power transmission

• US 7,969,755 B2
• Filed: 09/09/2005
• Issued: 06/28/2011
• Est. Priority Date: 09/09/2005
• Status: Active Grant

• Current Assignee: Siemens Energy Global GmbH & Co. KG (Siemens AG)
• Original Assignee: Siemens AG
• Inventors: Davies, Mark, Huang, Hartmut, Retzmann, Dietmar, Dorn, Jörg
• Primary Examiner(s): BERHANE, ADOLF D
• Application Number:
  US12/066,320
• Publication Number:
  US 20080205093A1
• Time in Patent Office: 2,118 Days
• Field of Search: 363/34, 363/35, 363/37, 363/123, 363/131
• US Class Current: 363/35
• CPC Class Codes: H02J 3/1864 wherein the stepless control of reactive power is obtained by at least one reactive element connected in series with a semiconductor switch
• CPC Class Codes: H02J 3/28 Arrangements for balancing of the load in a network by storage of energy
• CPC Class Codes: H02J 3/36 Arrangements for transfer of electric power between ac networks via a high-tension dc link
• CPC Class Codes: H02M 1/0074 Plural converter units whose inputs are connected in series
• CPC Class Codes: H02M 7/483 Converters with outputs that each can have more than two voltages levels
• CPC Class Codes: H02M 7/4835 comprising two or more cells, each including a switchable capacitor, the capacitors having a nominal charge voltage which corresponds to a given fraction of the input voltage, and the capacitors being selectively connected in series to determine the instantaneous output voltage
• CPC Class Codes: H02M 7/49 Combination of the output voltage waveforms of a plurality of converters
• CPC Class Codes: H02M 7/797 using semiconductor devices only
• CPC Class Codes: H02M 7/81 arranged for operation in parallel
• CPC Class Codes: Y02E 40/10 Flexible AC transmission systems [FACTS]
• 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 device for the transmission of electrical energy includes at least one current converter. Each current converter has phase elements with respective arrangements of circuit elements that comprise at least two switchable power semiconductors each and at least two free-wheeling diodes, each connected in parallel thereto, and energy storing means. The transfer properties in or between power distribution networks are improved with the novel device. The device is provided with means for controlling the current converter in such a manner that the zero crossing, the amplitude and/or the instantaneous values of an alternating current of a transfer network that can be connected to the device and/or the direct current of a direct current line that connects at least one current converter to a direct current source, and/or the direct voltage and the direct current of at least three interconnected current converters can be controlled.

Claims

1. An apparatus for electrical power transmission, comprising:

at least one converter having phase elements, each of said phase elements including an assembly of switching elements, each of said switching elements having at least two switchable power semiconductors and at least two freewheeling diodes, respectively connected in parallel with said power semiconductors, and each of said switching elements having energy storage means;

controller means for closed-loop control of said at least one converter such that at least one of the following is controlled;

a zero crossing phase angle, an amplitude, and/or instantaneous values of an AC voltage of a transmission system to be connected to the apparatus; and

/or

a DC voltage and a direct current on a DC voltage line connecting said at least one converter to a DC voltage source; and

/or

a DC voltage and a direct current of at least three converters that are connected to one another.

2. The apparatus according to claim 1, wherein said switching elements of one said phase element are connected in series, said switching elements are an even number of said switching elements, and a load connection or power supply system is disposed centrally on the series circuit formed by said series-connected switching elements.

3. The apparatus according to claim 1, wherein each of said phase elements has two parallel branches each having an even number of switching elements connected in series.

4. The apparatus according to claim 3, which comprises a transformer winding connecting at least said two parallel branches.

5. The apparatus according to claim 3, which comprises a parallel branch connection galvanically connecting at least two parallel branches.

6. The apparatus according to claim 1, wherein a plurality of said phase elements of a converter are connected in parallel with one another.

7. The apparatus according to claim 1, wherein a plurality of said phase elements are connected in series with one another.

8. The apparatus according to claim 1, which comprises energy storage means connected in parallel with said phase elements.

9. The apparatus according to claim 1, wherein each said phase element includes at least one impedance, or is connected to a respectively other phase element via an impedance.

10. The apparatus according to claim 1, wherein said at least one converter is connected in parallel with the transmission system or with the DC voltage line.

11. The apparatus according to claim 1, wherein said at least one converter is connected in series with the transmission system or the DC voltage line.

12. The apparatus according to claim 1, wherein said DC voltage source is a converter.

13. The apparatus according to claim 1, wherein, at least in places, the DC voltage line is at least one line selected from the group consisting of a gas-insulated transmission line, a cable, and an overhead line.

14. The apparatus according to claim 1, wherein said at least one converter has line-commutated power semiconductors.

15. The apparatus according to claim 1, wherein the DC voltage line has one or two poles.

16. The apparatus according to claim 1, wherein said DC voltage line is an impedance.

17. The apparatus according to claim 1, which comprises at least one further diode connected in parallel with said switching elements.

18. The apparatus according to claim 1, wherein said transmission system has one or more phases.

19. The apparatus according to claim 1, wherein said energy storage means comprise one or more capacitors.

20. The apparatus according to claim 1, wherein said at least one converter is connected to the DC voltage line by way of an energy storage device.

21. The apparatus according to claim 1, wherein said at least one converter is one of three converters each connected to the DC voltage line by way of a respective energy storage device.

22. A system, comprising an apparatus according to claim 1 and a transmission system connected to said apparatus and configured to have at least one phase and to carry an alternating current.

23. The apparatus according to claim 1, wherein said controller means controls the zero crossing phase angle, the amplitude, and/or instantaneous values of the AC voltage of a transmission system connected to the apparatus.