Differential flow anomaly detection method

The invention provides a differential current anomaly detection method, which comprises the steps of S1, detecting whether a single-phase or inter-phase short-circuit grounding fault exists in a powergrid or not, if so, reading protection event data of the whole power grid when the power grid fault occurs, and obtaining a differential current anomaly detection interval list; S2, calling all interval protection device waveforms and all fault recorder waveforms from the differential current anomaly detection interval list, and carrying out amplitude correction and phase correction; S3, selecting a protection interval from the retrieved data, and intercepting a protection device current waveform and a fault recorder current waveform of the interval in a waveform comparison interval; S4, carrying out waveform comparison, waveform amplitude, waveform distortion and harmonic characteristic calculation, and acquiring waveform characteristic vectors of the interval; and S5, calculating a waveform detection result fea