Ferroresonance phenomena in medium-voltage isolated neutral grids: a case study

Abstract

Power quality events associated with the occurrence of ferroresonances in medium voltage (MV) isolated-neutral distribution power systems are well known but they still happen in nowadays grids. This work deals with the study of ferroresonance events in a distribution grid region characterised by having distributed generators and being lightly loaded. The study shows that well-known solutions, i.e. voltage transformer damping, are difficult to apply due to the legal considerations and, alternatively, the distribution system operator can take actions to minimise their effect on the distribution system. The data provided and the obtained results correspond to a three-year measurement campaign at a real MV isolated-neutral distribution power system. The measurements and analysis given allow reaching general conclusions about the distribution system operation oriented to minimise the effect of ferroresonances.