MODULE FOR A CONVERTER AND METHOD FOR CONTROLLING FAULT CURRENTS IN A CONVERTER

Abstract

A module for a converter includes submodules, a first coupling inductor and a second coupling inductor which is activatable in the event of a fault. A method for controlling fault currents in a converter is also provided.

Claims

1. A module for a converter, the module comprising: submodules; a first coupling inductor; and a second coupling inductor being connected in series with said submodules and said first coupling inductor, said second coupling inductor being activatable in an event of a fault.

2. The module according to claim 1, which further comprises a switching device connected in parallel to said second coupling inductor.

3. The module according to claim 2, wherein said switching device is constructed to be opened in an event of a fault.

4. The module according to claim 2, wherein said switching device includes two antiparallel-connected semiconductor switches.

5. The module according to claim 2, wherein said switching device includes a mechanical switch.

6. The module according to claim 2, wherein said switching device includes a surge arrester.

7. The module according to claim 2, wherein said switching device is constructed to be closed in an event of a fault.

8. The module according to claim 1, wherein said second coupling inductor is allocated to one of said submodules.

9. The module according to claim 1, which further comprises at least one additional coupling inductor.

10. The module according to claim 1, wherein said submodules have semiconductor switches being controllable in an event of a fault differently from in normal operation and each depending on a total coupling inductance activated in the module.

11. The module according to claim 1, wherein said first and second coupling inductors are constructed as magnetically coupled partial windings.

12. The module according to claim 11, wherein said partial winding corresponding to said second coupling inductor is activatable by an actuator.

13. The module according to claim 12, wherein said actuator has two antiparallel-connected semiconductor switches.

14. The module according to claim 12, wherein said actuator has a current source.

15. The module according to claim 12, wherein said actuator has a capacitor.

16. A method for controlling fault currents in a converter, the method comprising the following steps: providing the converter with modules, submodules and a first coupling inductor; detecting a fault event; and activating a second coupling inductor in an event of a fault.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

[0036] FIG. 1 is a schematic diagram of a modular multi-level converter;

[0037] FIG. 2 is a schematic diagram of a static reactive power controller;

[0038] FIG. 3 is a schematic diagram of a first example embodiment of a module according to the invention;

[0039] FIG. 4 is a schematic diagram of a detailed view of a second coupling inductor with a switching device;

[0040] FIG. 5 is a schematic diagram of a first example embodiment of a switching device;

[0041] FIG. 6 is a schematic diagram of a second example embodiment of a switching device; and

[0042] FIG. 7 is a schematic diagram of an example embodiment of first and second coupling inductors which are constructed as magnetically coupled partial windings of a single coil.

DETAILED DESCRIPTION OF THE INVENTION

[0043] Referring now to the figures of the drawings in detail and first, particularly, to FIG. 1 thereof, there is seen a modular multi-level converter 1 which is connected on the AC voltage side to a three-phase network AC. Connections DC+ and DC are present on the DC voltage side. A module 10 is used in each case for each converter branch 2-7.

[0044] FIG. 2 shows a static reactive power controller 8 which is used for reactive power compensation in the three-phase alternating-current voltage network AC. It has three branches 11-13, each with one module 10.

[0045] FIGS. 3 and 4 show a module 10 in a detailed view. A first coupling inductor 20, a device 30 for increasing the total inductance and submodules 40 are connected in series. The device 30 has a second coupling inductor 50 and a switching device 60.

[0046] FIG. 5 shows a first example embodiment of a switching device 60 which has two antiparallel-connected semiconductor switches (e.g. IGBTs) 34, 35 in switching device branches 31 and 32. A surge arrester 36 is disposed in a switching device branch 33.

[0047] FIG. 6 shows a second example embodiment of a switching device 60 which has a mechanical switch 38 in a switching device branch 37. A surge arrester 36 is disposed in a switching device branch 33.

[0048] FIG. 7 shows an example embodiment of first and second coupling inductors 20, 50 which are constructed as magnetically coupled partial windings of a single coil 22. The partial windings are wound in opposition. The partial winding corresponding to the second coupling inductor can be activated or deactivated by using an actuator 21.