Power transmission line single-phase earth fault direction discrimination method based on dynamic data window

The invention relates to a power transmission line single-phase earth fault direction discrimination method based on a dynamic data window. The method comprises the following steps: measuring a faultphase voltage sampling value, a fault phase current sampling value, a fault phase negative sequence voltage sampling value and a zero sequence current sampling value at each sampling moment at a powertransmission line protection installation position, calculating the length of the dynamic data window, calculating whether the single-phase earth fault direction criterion of the power transmission line is true or not by utilizing the fault phase electric quantity sampling value of the length of the dynamic data window, and if yes, judging that the single-phase earth fault occurs in the positivedirection of the power transmission line. According to the method, only the fault phase electric quantity sampling value smaller than a 1/4 period data window is needed to participate in operation, the needed data window is sho