Bezruchko V. Improving power quality in power supply systems of objects of construction by zero sequence current filters

This thesis is devoted to the development of new circuit decisions of zero sequence currents filters with smaller mass and cost indicators and to the improvement of the existing filters. Furthermore, this thesis offers a solution of a problem concerning a rational distribution of these filters on the plan of the existing power-supply system of a facility siting, which will subsequently enable cost-reduction and will lead to a rise in efficiency of measures aimed at improving quality and reducing power losses in the system. This paper also introduces new designs of "three phase - two phase" autotransformer zero sequence currents filters with the improved technical and economic indicators. According to the methods of calculation of zero sequence inductance of filters' windings, employed by the author of the thesis, it is shown that the most appropriate method is a manufacture of coils with alternating layers windings, for reduction of inductance and improvement of processability in filter manufacturing. In addition, the developed mathematical models of zero sequence currents filters are provided in this paper. With the help of these models, comparisons of designs of filters according to their weight and cost are carried out, as a result, giving the opportunity to choose circuit and design decisions of filters with the improved technical and economic indicators, taking into account the requirements to them and manufacturing possibilities. All in all, the paper provides a method for the solution of the problem of a rational distribution of zero sequence currents filters based on the plan of the existing power-supply system. This method considers not only the significance of voltage harmonics amplitudes in subsystems, but also the significance of current harmonics amplitudes in a neutral wire and capacity losses in the power-supply system, thus providing an opportunity to lower the higher harmonics of voltage and current, and to reduce power losses. The filters are manufactured by the LLC "КП ЭНРИ" - (Kiev).