Power distribution network hybrid grounding system and closed-loop switching operation control method

The invention provides a hybrid grounding system of a power distribution network. The hybrid grounding system comprises a small-resistance grounding system on the left side, an arc suppression coil grounding system on the right side and a loop closing connection circuit used for connecting the small-resistance grounding system and the arc suppression coil grounding system. Wherein the loop closing point of the small-resistance grounding system is located at the head end of the feeder line 1, so that the inversely-cut line and the feeder line of the small-resistance grounding system share one set of zero-sequence current protection; the side, close to the arc suppression coil grounding system, of the closed-loop connection circuit is provided with zero-sequence current protection, and the side, close to the small-resistance grounding system, of the closed-loop connection circuit and a feeder line of the small-resistance grounding system share one set of zero-sequence current protection. The invention also prov