The digital transformation of the electric power industry is one of the priority tasks for the development of the industry. Wavelet transform is widely used in the electric power industry to analyze the dynamics of complex non-linear non-stationary processes. The article proposes a method for calculating transient processes in electrical networks based on a recursive algorithm. The approximating and detailing wavelet coefficients of the discrete wavelet transform are used as the voltage signal. To select the optimal wavelet function, it is proposed to use a criterion that takes into account the accuracy of the signal recovery as a result of the inverse wavelet transform. The nature of the change in the calculation result with an increase in the number of iterations is shown. The results of a numerical experiment for a 110 kV network when calculating a three-phase short circuit showed an acceptable accuracy of the developed technique. The proposed technique makes it possible to compress the volume of transmitted digital data on normal and emergency modes of electrical networks.