Investigation of Controlled Fault Interruption Strategies in Isolated MV Distribution Systems

The paper presents an investigation of the applicability of controlled fault interruption techniques in radial, isolated, medium voltage distribution networks. In particular, when single phase-to-earth faults occur in isolated distribution systems, it is necessary to mitigate switching overvoltages. A comprehensive set of simulations has been carried out to evaluate the sensitivity of overvoltage phenomena to different switching strategies, with the aim of highlighting the possible methods to mitigate them and, thus, avoid harmful effects on electrical systems. The presented results show slight benefits in reducing overvoltages in the primary substation by independently controlling each pole of the switching device, regardless of the considered switching strategy. The inherent limitations of this approach are hence discussed, highlighting the current technological limitations, and alternative mitigation strategies are suggested.