Improved Schwarz arc model-based power distribution network closed-loop back-off grounding fault analysis method

The invention discloses an improved Schwarz arc model-based power distribution network closed-loop inverted-cut grounding fault analysis method, which comprises the following steps of: improving a Schwarz arc mathematical model by referring to an arc time constant containing an arc length parameter to obtain an improved Schwarz arc model containing the arc length parameter; constructing a hybrid grounding system simulation model in which the NRS and the NES are in contact operation; the method comprises the following steps: analyzing conditions of a multi-band line and a load after single-phase grounding faults occur at different positions of a hybrid grounding system and closed-loop switching is finished, summarizing the influence of the single-phase grounding faults on original protection of an NRS and grounding residual current of an NES after two grounding systems are closed, and proposing a protection improvement scheme and closed-loop switching conditions in a hybrid grounding mode; according to the inv