Novel Structure Designs for Power Distribution Systems With Superior Performance in Detecting HIEFs

In this letter, we propose two new structure designs and their related detection criteria in identifying extremely high impedance earth faults (HIEFs). First, two subnetwork division modes are introduced to limit the coupling flow of zero-sequence current between the faulty line and sound lines where two kinds of power transformers are individually applied. Second, following the quantitative discussions about the effect of the proposed structures on original power grid, e.g., power supply reliability and the probability of bushfire caused by HIEFs, two novel detecting judgement criteria of merely using the vectorized variation of zero-sequence voltage are mathematically formulated. Numerical simulations reveal that in contrast with traditional solutions, the two judgement criteria present more superior and sensitive performance in detecting HIEFs.