Tuhai D. Efficiency of Smart Grid energy supply systems with semiconductor power converters

Object of the study: electromagnetic processes in three-phase energy supply systems with energy-saving semiconductor converters and high-intensive energy storages. The aim of the study: to subtend and to generalize the instantaneous active and reactive power modern theory for evaluation of the energy-saving effect from the use in three-phase energy supply systems with bidirectional power flow of semiconductor power converters. Research methods and equipment: modern theory of instantaneous active and reactive powers, electrical circuits theory, spatial vectors theory; elements of matrix calculus and vector analysis; transformation of spatial Cartesian coordinate systems; methods for solving systems of differential and algebraic equations; simulation modeling. Theoretical and practical results: a method to choose the phase reactors inductance of the power active filter (PAF), taking into account the parameters of the load and the energy supply network; a method to measure the total power losses in a three-phase power supply system and a device for its implementation. Originality: new methods to calculate inductance of phase reactors of parallel PAF and active rectifier, which take into account the low-frequency and high-frequency components of electromagnetic processes and allow increasing the accuracy of the elements selection are developed; it is proved, that to increase the accuracy of the reactive power vector module calculation, it is necessary to take into account the instantaneous values of the phase voltages at the terminals of the energy source; a theorem of the minimum energy losses in three-phase energy supply systems is formulated and a calculated ratio for the total losses power is obtained; a mathematical connection between current unbalance coefficients of the inverse sequence, zero sequence, and the components of the total losses power, presented in pqr-coordinates, is established. Implementation: SPE "EOS", SE "RI "KhEMP", CE "Kharkov Metro", LLC SPA "Vertical", educational process of O.M. Beketov NUUE, NTU "KhPI". Area of use: electric power industry.