The fast and accurate detection of the single-phase-to-ground fault is of great significance for the reliability and safety of the power supply. In this paper

novel algorithms for distribution network protection were proposed with distributed parameters analysis in non-direct grounded systems. At first

novel generating mechanisms of zero-sequence voltage and residual current were proposed. Then the compositions of residue parameters

including residual current and residual admittances

were decomposed in detail. After that

an improved algorithm for a fault resistance calculation of a single phase-to-earth fault was also proposed

and the algorithm is much more convenient as it only needs to measure the variation of the zero-sequence voltage and does not need the prerequisites of the faulty feeder selection. Furthermore

the fault feeder can also be selected by an improved calculation algorithm of zero-sequence admittance of the faulty feeder

which cannot be affected by the asymmetry of the network. Theoretical analysis and the MATLAB/Simulink simulation results demonstrate the effectiveness of the proposed algorithms.