Voltage sag source locating method based on sequence disturbing active current direction

The invention discloses a voltage sag source locating method based on a sequence disturbing active current direction and belongs to automatic monitoring methods for power grid voltage sag source locating. The voltage sag source locating method includes: during power grid fault, a voltage sag source is located accurately by the disturbing active current direction under the action of disturbing voltage according to a linear circuit superposition principle; when disturbing active current is positive, a disturbing source is at the upstream position of a monitoring point; when the disturbing active current is negative, the disturbing source is at the downstream position of the monitoring point; a corresponding disturbing active current algorithm is defined and provided. The voltage sag source locating method based on the sequence disturbing active current direction has the advantages that the method is capable of locating voltage sag caused by various power grid faults determinately and applicable to power grids of radiation-type, ring-type, single-loop, double-loop, single-power-source and multi-power-source grid structures as well as voltage sag source locating caused by disturbance resulting from capacitor switching, transformer switching and large motor starting; voltage and current of the monitoring point need to be sampled synchronously according to the voltage sag source locating method.