Dynamische Kurzschlussstrombegrenzung auf Basis eines sechspulsigen Thyristorgleichrichters (English shop)

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Owing to the continuous expansion of grids, ever higher peak and steady-state short-circuit currents occur in electrical power supply networks in the event of a fault, which leads to increased thermal and mechanical stresses on the network elements. In addition, the growing amounts of energy that can be converted when an arc fault occurs result not only in further hazards for electrical installations but also for people. These increased risks in the event of a short circuit can be countered only to a limited extent, or only at considerable financial expense, using conventional equipment. Suitable, cost-effective short-circuit current limiting devices, by contrast, are able to control the aforementioned negative side effects of faults in electrical networks.

The cigré working group A 3.10 defines a short-circuit current limiter as a device that, in the event of a fault, limits the current in the critical network branch so that overloading of the system components does not occur. On the one hand, short-circuit current limiting devices should hardly impair any operational processes during fault-free normal operation and, on the other hand, should limit the short-circuit current quickly and reliably when a fault occurs. These requirements can be implemented in very different ways, so that a large number of possible solutions exists. Figure 1, in which the currents are referred to the amplitude of the unlimited steady-state short-circuit current, shows a typical short-circuit current curve without the use of a short-circuit current limiting device (SCCL for short) and two limited short-circuit currents. The limitation of the current iSCCL,1 is achieved by very rapid fault current interruption, as can be attained, for example, by an Is-limiter. Furthermore, other short-circuit current limiters, e.g. high-temperature superconducting SCCLs, allow a limited current flow iSCCL,2 to be maintained — at least for a short time.