The traditional resonance grounding method is hard to completely satisfy the requirement of suppressing normal neutral-to-ground voltage and self-extinguishing grounding fault arcs in asymmetry distribution systems. For improvement, a new grounding method of a Petersen-coil in parallel with a reactor is developed, and some novel techniques for insulation parameters measurement and Petersen-coil control are proposed in this paper. An interpolation algorithm is presented to calculate the distribution systems resonance frequency. The insulation parameters (including capacitance to earth, leakage ...