MODELING OF SWITCHING PROCESSES OF TRANSFORMER WINDING BRANCHES ACCORDING TO FACTORY SETTINGS

Mechanical load voltage regulators developed in the 20th century continue to be used in power systems. These switching devices are mainly installed in the neutral windings of 110 kV and above power transformers, which allows reducing their insulation class to 35 kV. Technological limitations do not allow the creation of semiconductor devices with characteristics equivalent to mechanical switches in terms of rated current and number of switching cycles, which explains the widespread use of devices with moving contacts.The urgency of development of new methods of diagnostics is conditioned by the exhausted resource of the majority of such devices. The prospects for the development of power transformer diagnostics are connected with the active implementation of artificial intelligence technologies. The presented study contributes to the solution of this problem by proposing a method of comparative analysis of oscillograms of contact system currents of switching devices obtained under operating conditions and during commissioning tests. Realization of this approach requires additional research and application of modern programming methods. Purpose of the research is to develop and verify the method of modeling of transient processes at switching of transformer winding branches with voltage regulator under load, based solely on the equipment passport data, with the subsequent creation of software for generation of typical oscillograms of contactor currents of the switching device. Materials and methods. The research was carried out on the basis of factory parameters of power transformer and switching device of RNTA-35/200 type. Mathematical methods and the basics of electrical circuit theory were used to calculate the inductive and total resistance of the high-voltage winding of the voltage converter, its dissipation inductance at each branch on the basis of factory parameters, as well as methods of functional programming to carry out modeling of oscillographic currents in the switching process of the switching device. Results. An innovative approach to reproduction of oscillograms of currents of the contact system of the voltage regulating device under load based on computer modeling of switching transients based solely on the equipment passport data is presented. The proposed methodology allows to reproduce typical characteristics of oscillograph currents similar to those obtained during commissioning works. Conclusions. The study confirmed the possibility of reliable modeling of transient currents during switching of voltage regulator taps on the basis of factory parameters of power transformer and switching device. For the switching device of RNTA-35/200 type the oscillogram of transient currents was obtained, which can serve as a typical one for diagnostics of the equipment condition by the method of comparison with real oscillographic current curves obtained by the operating personnel. The developed method allows for timely detection of contact system wear and prediction of the remaining life of electrical equipment, and also opens up new prospects for the creation of intelligent systems for monitoring the state of a control device under load.