Discharge phase calculation method

The invention relates to the technical field of intelligent power grids and discloses a discharge phase calculation method. The method comprises the following steps of S1, selecting a power frequencysampling rate of a monitoring terminal, and constructing a standard discrete sine sequence y(n) by a central station; S2, allowing the central station to collect and record sampling y(N) of N points in one period of y(n) and sends the sampling y(N) to the monitoring terminal; S3, acquiring a power frequency sequence w of which the field length is m periods, intercepting N groups of waveform data,and intercepting waveform data wi of the N points in one period for an ith point; and S4, respectively calculating the correlation between the N groups of waveform data and the sampling y(N) of one period of the standard discrete sine sequence, and taking a starting point corresponding to the wj with the maximum correlation as an initial phase of the power frequency sequence. The problems that thecomplex trigonometric func