Delay period single-ended protection method and system suitable for new energy power system

The invention discloses a delay period single-ended protection method and system suitable for a new energy power system, and the method comprises the steps: calculating the break variable of 1-mode voltage and current according to the modulus voltage and current of the three-phase voltage and current of a power transmission line, starting protection, and calculating 1-mode fault voltage reverse traveling waves according to the break variable of 1-mode voltage and current; extracting a wave head arrival moment of a second traveling wave in a given time window, then extracting data window data from the starting moment to the wave head arrival moment of the second traveling wave, extracting voltage and current first traveling waves based on the data window data, and judging a fault direction through a fault direction criterion; and when the fault direction is judged to be a positive direction fault, fitting the wavefront of the first fault voltage traveling wave by using a Levenberg-Marquardt algorithm to obtain