Method and device for determining fault point location of neutral point non-effective grounding system

The invention provides a method and device for determining a fault point location of a neutral point non-effective grounding system. The determination method comprises the following steps that whether or not a line in the neutral point non-effective grounding system has a single-phase grounding fault is determined; if the single-phase grounding fault occurs, a circuit breaker of a control line will close again after a first trip; if the re-closure of the circuit breaker fails, a permanent fault of the line is determined; if the re-closure of the circuit breaker is successful, an instantaneous fault of the line is determined; under the condition that the permanent failure of the line is determined, a control circuit breaker is trips again; the re-closure time of the circuit breaker and the arrival time of reflection waves at the single-phase grounding fault point of the line after the circuit breaker trips again are obtained, and the location of the single-phase grounding fault point of the line is determined