Schutzalgorithmen für dynamisch vermaschte Ringnetzstrukturen mit dezentraler Einspeisung

Description

In recent years and decades there has been a massive increase in distribution generation (DG), for which the existing electrical energy systems were not designed. In order to prevent possible violations of voltage and current limits resulting from this additional infeed, the degree of meshing can be increased, which enables further paths for the power to flow. In the simplest case, this leads to closing rings in previously openly operated ring structures. To perform this task, no new equipment is required, and the change of topology can basically be accomplished instantly. However, existent protection systems in distribution system networks can merely handle closed rings with a high share of DG adequately in many cases. As part of this paper, protection algorithms for relays on the busbar as well as on the (former) point of ring separation were developed, which do justice to this new constellation in the event of asymmetrical faults (single phase and two phase faults). The algorithms function on the basis of locally measured currents and voltages in symmetrical components. No communication channels across stations are required, this means, the application of the proposed algorithms does not require any additional infrastructure with the exception of new relays or the implementation of the proposed algorithms in existing relays respectively. The application of the algorithms leads to a reduced fault clearing time and thus diminishes the probability of disconnection of further DEA due to prolonged undervoltage situations. Furthermore, the improved fault localization enables troubleshooting measures to be started more quickly. In this way, this paper contributes to the integration of large numbers of DG into the existing network by avoiding massive network expansion measures at the same time.