Arrangement for voltage conversion

• US 8,422,260 B2
• Filed: 05/06/2008
• Issued: 04/16/2013
• Est. Priority Date: 05/06/2008
• Status: Active Grant

• Current Assignee: Hitachi Energy Limited (Hitachi, Ltd.)
• Original Assignee: ABB Technology AG (ABB Limited)
• Inventors: Asplund, Gunnar
• Primary Examiner(s): Tran, Nguyen
• Application Number:
  US12/991,161
• Publication Number:
  US 20110069517A1
• Time in Patent Office: 1,806 Days
• Field of Search: 363/55, 363/56.01, 363/56.02, 363/71, 363/72, 363/131, 363/132, 363/135, 363/136
• US Class Current: 363/131
• CPC Class Codes: H01F 27/34 Special means for preventing or reducing unwanted electric or magnetic effects, e.g. no-load losses, reactive currents, harmonics, oscillations, leakage fields
• CPC Class Codes: H01F 29/02 with tappings on coil or winding; with provision for rearrangement or interconnection of windings
• CPC Class Codes: H01F 30/12 Two-phase, three-phase or polyphase transformers
• CPC Class Codes: H01F 38/00 Adaptations of transformers or inductances for specific applications or functions
• 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 1/0064 Magnetic structures combining different functions, e.g. storage, filtering or transformation
• 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: Y02E 60/60 Arrangements for transfer of electric power between AC networks or generators via a high voltage DC link [HVCD]

Abstract

An arrangement for converting direct voltage into alternating voltage and conversely has a Voltage Source Converter with at least one phase leg connected to opposite poles (5, 6) of a direct voltage side of the converter and a series connection of switching cells arranged between said poles. Each half (8, 9) of this series connection is connected to a mid point forming a phase output by a phase reactor. The phase reactors of a said phase leg are built in a transformer (30) configured to connect said phase output to an alternating voltage phase line (28) by forming a primary winding each of the transformer arranged to interact with a secondary winding thereof connected to the alternating voltage phase line.

Claims

1. An arrangement connected to a direct voltage network for transmitting high voltage direct current, said arrangement being provided for converting direct voltage into alternating voltage and conversely, said arrangement comprising:

a multi-cell Voltage Source Converter having;

at least one phase leg connected to opposite poles of a direct voltage side of the converter and comprising a series connection of switching cells, each switching cell having at least one energy storing capacitor as well as two terminals respectively connected to two immediately adjacent switching cells in said series connection of switching cells, a mid point of said series connection of switching cells dividing said series connection of switching cells into two halves of said series connection of switching cells and forming a phase output being configured to be connected to an alternating voltage side of the converter, and

for each half of said series connection of switching cells, an inductance device in the form of a phase reactor arranged to connect a corresponding one of the two halves of said series connection of switching cells to said mid point, and

a transformer, for each of the at least one phase leg, configured to connect said phase output to an alternating voltage phase line associated with said phase leg, the transformer including two primary windings and a secondary winding,

wherein said phase reactors of the at least one phase leg are built in in said transformer by using the two primary windings of the transformer, each of the two primary windings connects a corresponding one of the two halves of said series connection of switching cells to the mid point, each of the two primary windings of the transformer is arranged to interact with the secondary winding of the transformer that is connected to said alternating voltage phase line, and said two primary windings are so located with respect to each other such that a dc component of a current flowing from one of said poles to the other of said poles through said mid point flows in substantially opposite directions through the two primary windings.

2. The arrangement according to claim 1, wherein said two primary windings are arranged substantially in parallel with each other.

3. The arrangement according to claim 1, wherein said two primary windings extend in the longitudinal direction thereof between two planes in common being substantially perpendicular to the longitudinal extension of the primary windings.

4. The arrangement according to claim 1, wherein said secondary winding of the transformer is arranged in parallel with said two primary windings and outside of a space between said two primary windings.

5. The arrangement according to claim 1, wherein said secondary winding of the transformer is arranged substantially in parallel with said two primary windings and within a space between said two primary windings.

6. The arrangement according to claim 1, wherein the number of the switching cells of said phase leg is ≧

4, ≧

12, ≧

30 or ≧

50.

7. The arrangement according to claim 1, wherein semiconductor devices of the switching cell assemblies are IGBTs (Insulated Gate Bipolar Transistor), IGCTs (Integrated Gate Commutated Thyristor) or GTOs (Gate Turn-Off Thyristor).

8. The arrangement according to claim 1, wherein it is configured to have said direct voltage side of the converter connected to said direct voltage network for transmitting High Voltage Direct Current (HVDC) and the alternating voltage side connected to an alternating voltage phase line belonging to an alternating voltage network.

9. The arrangement according to claim 1, wherein said Voltage Source Converter is configured to have a direct voltage across said two poles being 1 kV-1200 kV, 10 kV-1200 kV or 100 kV-1200 kV.

10. The arrangement according to claim 2, wherein said two primary windings extend in the longitudinal direction thereof between two planes in common being substantially perpendicular to the longitudinal extension of the primary windings.

11. The arrangement according to claim 2, wherein said secondary winding of the transformer is arranged in parallel with and outside a space between said two primary windings.

12. The arrangement according to claim 3, wherein said secondary winding of the transformer is arranged in parallel with said two primary windings and outside of a space between said two primary windings.

13. The arrangement according to claim 2, wherein said secondary winding of the transformer is arranged substantially in parallel with said two primary windings and within a space between said two primary windings.

14. The arrangement according to claim 3, wherein said secondary winding of the transformer is arranged substantially in parallel with said two primary windings and within a space between said two primary windings.

15. The arrangement according to claim 4, wherein said secondary winding of the transformer is arranged substantially in parallel with said two primary windings and within a space between said two primary windings.

16. The arrangement according to claim 2, wherein the number of the switching cells of said phase leg is ≧

4, ≧

12, ≧

30 or ≧

50.

17. The arrangement according to claim 3, wherein the number of the switching cells of said phase leg is ≧

4, ≧

12, ≧

30 or ≧

50.

18. The arrangement according to claim 4, wherein the number of the switching cells of said phase leg is ≧

4, ≧

12, ≧

30 or ≧

50.

19. The arrangement according to claim 5, wherein the number of the switching cells of said phase leg is ≧

4, ≧

12, ≧

30 or ≧

50.