Authors of this article review and analyze the main trends in the modern distribution networks development for electricity supply. These distribution networks can function effectively only with extensive and adequate use of parametric and non-parametric identification. We propose the general approach to parametric identification in power distribution networks. The authors of this article developed the applied method for the parametric identification of voltage converters in digital substations based on this approach. We select an adequate model structure of simulated electrotechnical objects. Parametric identification results are input data that organize the diagnostic process of digital signal converters.