Using UPQC to control the fourth-wire current in four-wire three-phase distribution networks under unbalanced load conditions

摘要

Currently, on one hand, with the expansion of the using nonlinear loads such as industrial converters, electrical arc furnaces and switching power sources in distribution networks, and the increase of sensitive electronic loads that require an ideal sinusoidal voltage source, the issue of power quality has been considered seriously. Also, the competitiveness of the electric energy market in many countries has led to an increase in investment in the supply of good quality electric power. One of the ways to improve power quality is to install UPQC in the distribution network, especially near non-linear loads. UPQC is a combination of two active series and parallel filters, which are provided by a storage element and have a common DC connection (Fryze). This compensator belongs to the new generation of power quality improvement devices and was first proposed as the universal active filter in 1995. It can be concluded that if the proposed upqc control system is applied to the distribution system in this research, then the following optimal results will result, which will have important implications in a distribution network in order to resolve the power quality issue. The simulation results have been shown by MATLAB that optimally balances the load current and compensates the current of the non-conductor wire that flows toward the neutral transformer.