Method for the fault management of a fault in a DC voltage line and converter assembly for carrying out the method

1. A method for the fault management of a fault on a DC voltage side of a converter assembly, the method comprising the following steps:

providing the converter assembly including a modular multi-stage converter having switching modules each including a plurality of semiconductor switches and at least one energy store;

providing some of the switching modules as switching modules of a first type having terminals and providing some others of the switching modules as switching modules of a second type having terminals;

during operation of the converter assembly, generating a positive switching module voltage, a negative switching module voltage or a zero voltage at the terminals of the switching modules of the first type, and generating a positive switching module voltage or a zero voltage at the terminals of the switching modules of the second type;

detecting a DC voltage side fault;

actuating the switching modules of the first type to cause a polarity of energy store voltages thereof to correspond to a polarity of a fault current; and

charging the energy stores of the switching modules of the first type to a voltage in excess of a rated voltage thereof.

2. The method according to claim 1 , which further comprises establishing a target value for a DC voltage side converter voltage at a negative value.

3. The method according to claim 1 , which further comprises setting the rated voltage of the switching modules of at least one of the first type or the second type between 1 kV and 5 kV.

4. The method according to claim 1 , which further comprises providing the switching modules of the first type as full-bridge switching modules.

5. The method according to claim 1 , which further comprises providing the switching modules of the second type as half-bridge switching modules.

6. The method according to claim 1 , which further comprises regulating a DC voltage side current to zero.

7. The method according to claim 1 , which further comprises terminating the fault management if an absolute magnitude of a DC voltage side current falls below a predefined current threshold and remains below the predefined current threshold for a predefined time interval.

8. The method according to claim 1 , which further comprises using an additional DC voltage side parallel path including a diode and an arrester to limit a negative DC voltage side voltage.

9. The method according to claim 1 , which further comprises carrying out a transition to normal operation upon an expiration of a deionization time.

10. The method according to claim 1 , which further comprises operating the switching modules with a voltage being higher than an operating voltage by a factor of 1.1 to 1.5.

11. A converter assembly, comprising:

a modular multi-stage converter including switching modules;

each of said switching modules having a plurality of semiconductor switches and at least one energy store, some of said switching modules being switching modules of a first type having terminals, and some others of said switching modules being switching modules of a second type having terminals;

said switching modules of said first type configured to generate a positive switching module voltage, a negative switching module voltage or a zero voltage at said terminals of said switching modules of said first type during operation of the converter assembly;

said switching modules of said second type configured to generate a positive switching module voltage or a zero voltage at said terminals of said switching modules of said second type during operation of the converter assembly; and

a control device configured for:

detecting a DC voltage side fault;

actuating said switching modules of said first type to cause a polarity of energy store voltages thereof to correspond to a polarity of a fault current; and

charging said energy stores of said switching modules of said first type to a voltage in excess of a rated voltage thereof.