Power distribution network flexible grounding optimization evaluation method

The invention discloses a power distribution network flexible grounding optimization evaluation method, and belongs to the technical field of power distribution networks. The prior art lacks an optimization evaluation method. According to the method, the state characterization modes of the indexes on the voltage-reduction symmetric operation power distribution network in different states can be analyzed, the power distribution network ground fault phase voltage-reduction symmetric operation regulation and control multi-level dynamic evaluation method is further researched, and the operation state and evolution trend of the power distribution network are described from different side faces. The method comprises the following steps: firstly, using a bifurcation theory to research the extinguishing of a nonlinear fault arc, reconstructing the intrinsic relation with the line insulation strength, and establishing a corresponding risk assessment index; studying a distribution feeder line operation state space tran