Adaptive Current Protection Against Earth Faults in 6 – 10 kV Cable Networks

Resumo

In 6 – 10 kV cable networks with isolated neutral, overcurrent protections are widely applied to earth fault protection based on components of working frequency, and in compensated cable networks based on higher harmonics of the zero-sequence current. The selectivity and stability of functioning of the former is, to a significant extent, limited by the effect on their operation of transient processes during arc earth faults, and of the latter by the instability of the level of the higher harmonics in the SPEF current, depending on the network operating mode. An adaptive method is examined for implementing the specified protections to ensure improvement of their technical capability.