Power losses from non-sinusoidal currents in rural electrical networks of 0.4 kV

A review of scientific articles in journals over the past few years shows that the problems associated with the presence of non sinusoidal currents in rural electrical networks are very relevant. The issue of the occurrence of periodic inharmonic currents and their effect on various elements of 0.4 kV electrical networks such as power lines, transformers, reactive power compensation installations is considered. There has been shown the main difference between such currents and the complexity of working wit h them as opposed to harmonic quantities. There has been conducted research in the production conditions of the "Vyborzhets" agricultural company, which have shown a significant non sinusoidal current shape curve in linear conductors. At the same time, the current shape curve turns out to be symmetrical with respect to the time axis, which allows us to conclude that there is no constant component and all even harmonics in it. Using high precision electrical measuring systems "Energomonitor 3.3T1", experimen tal studies of power losses from nonlinear currents produced by VIALOX NAV E type DNAT lamps with transformers with various winding connection schemes were carried out: Y/Yn, Y/YnSU, Y/Zn. The available methods for calculating active losses from inharmonic periodic currents are considered, and a new, patented method for calculating losses from non sinusoidal currents in a line with nonlinear symmetrical load based on the method of symmetrical components is proposed. The criterion of losses from non sinusoid al currents in the line has been calculated according to experimental studies and a graph of changes in this criterion depending on the load capacity has been constructed. It is shown that the highest value of the loss criterion from non sinusoidal currents in the line, and therefore the magnitude of the losses, are observed when using a transformer with a Y/Zn winding connection scheme, the lowest when using a transformer with a Y/Yn winding connection scheme. It is concluded that it is advisable to use a transformer with a Y/Yn winding connection scheme to reduce line losses from non sinusoidal currents with nonlinear symmetrical load.