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The new method of parametrical identification of three winding transformer by using phase domain is proposed. Transformer model represents as lattice equivalent circuit.

Application intellectual networks (smart grid) technologies for electric power quality management in systems of alternating current railroads’ power supply are considered. The structure of intellectual traction power supply system is described. Classification of management technical means for electric power modes and quality is given. The algorithm of intellectual electrical power traction systems modes’ modeling is offered. This algorithm differs by sharing of imitating and dynamic models of the active smart grid elements in its basis. The modeling results confirm applicability of the developed methods for the solution of electric power quality management’s problems.

Transfer of railway lines on the high-speed movement demands strengthening of traction power supply system.Such strengthening can be carried out on the basis of symmetrizing transformers and coaxial cables use.Means of computer modeling of such networks which can be realized on the basis of the methods developed at Irkutsk state transport university are necessary for the solution of practical application of traction networks with the symmetrizing transformers and coaxial cables.Complex technical solution including both from the designated ways of traction power supply strengthening is of interest. Strengthening provides the additional effects consisting in improvement of electric power quality in the feeding high-voltage networks and not traction consumers' power supply,and also in decrease in losses of the electric power and energy efficiency increase. Results of computer modeling of 2х25 kV traction power supply systems with Woodbridge symmetrizing transformers and coaxial cables are given.Modeling was carried out for three options: traditional scheme of 2х25 kV traction network; traction power supply system equipped with the modified Woodbridge transformers; the complex technical solution which is included the symmetrizing transformers and coaxial cables. Modeling results have allowed the following conclusions: application of coaxial cables promotes increase of contact net voltage; due to use of Woodbridge modified transformers it is possible to lower significantly negative sequence asymmetry factor on high voltage buses of traction substations; the greatest effect takes place at complex use of the symmetrizing transformers and coaxial cables.

The technique of parametrical identification of alternating current railroad traction network is offered. The technique allows receiving trellised equivalent circuits of a traction network which in the presence of measurements’ errors of voltage and currents vectors which aren't exceeding 0,5 % 0,5º give rather high precision of systems modes calculation of traction power supply, providing the correct solution of many practical tasks. Computer modeling showed that uniform traction network mode errors on voltages don't exceed 0,4 % and 0.2º , on currents - 0,9 %, 1.3º.

Researching subject which are presented in article is the emergency modes in 25 kV traction power supply systems caused by the short circuits (SC). The research purpose consisted in the analysis of calculation SC currents errors evolving from the reactances determined by SC power at the simplified modeling of external network. For achievement of formulated purpose comparative calculations of SC currents for a number of standard schemes of 25 kV system when using full models in phase coordinates and with use of simplified electric power system (EPS) reactances are executed. Modeling has shown that calculations of SC currents of contact network of deadlock substation by EPS reactances give the acceptable accuracy for feeder current of substation near which there is a short circuit. The calculation error of remote substation feeder current can reach +100% at SC power on inputs of substation about 300 MV·A, but decrease to values about 10% at the SC power of 2500 … 3000 MV·A. At food of group of traction substations from two 110 kV lines calculation error for equivalent reactances it is much less, however at SC power about 300 MV·A errors reach 35% and decrease to 10% at SC power on substation inputs more than 550 MV·A. Variant of traction substations power supply from two 220 kV power lines differs in small calculation errors of SC currents for equivalent external power supply reactances: differences from full scheme don't exceed 9% at SC powers of 1200 MV·A or more. The received results can be used at improvement existing and creation of new definition techniques for SC currents in 25 kV traction networks.