Abstract
Voltage sags/swells and harmonics are recurring problems in electric energy distribution systems. In order to solve these issues, several dynamic voltage restorer (DVR) topologies, such as the conventional three-wire DVR, have been proposed in the literature. Despite its capability of mitigating voltage disturbances, many researchers have established that conventional three-wire DVR cannot compensate for zero sequence voltage disturbances. In this paper, an in-depth study of the conventional three-phase DVR is presented, which shows that this DVR topology can also be used to attenuate zero sequence voltage components without increasing control complexity. The necessary conditions for this to occur are discussed in details and a brief comparison between the conventional three-wire DVR and other DVR topologies that can compensate for zero sequence voltage disturbances is made. Experimental results are included to validate the theoretical study.
Highlights
Due to the advance of microelectronics, sensitive power electronics devices have been increasingly used in all types of industries
The dynamic voltage restorer (DVR)’s controllers and the reference generation were implemented in a dSPACE plataform, model DS1005, featuring a processor running at 1 GHz [19]
In order to extend the analysis presented in the previous paragraph, Figures 8 and 9 show the evaluation of the zero sequence attenuation range for a conventional DVR with the parameters shown in Table 1, but considering RL loads (|Zl| = Zbase and PF = 0.8)
Summary
Due to the advance of microelectronics, sensitive power electronics devices have been increasingly used in all types of industries. Considering that the neutral points of grid and load are connected together, the currents ila, ilb and ilc may contain homopolar component If this happens, since the switch Sx is considered closed in this analysis, the zero sequence currents that circulate through the primary windings of the injection transformers will be present in their secondary windings, being part of Idvr_a, Idvr_b and Idvr_c. As presented in [16], none of the terms in (8) can be controlled by the converter This means that a zero sequence disturbance in the grid voltage cannot be compensated by the DVR of Figure 1 and a homopolar voltage component would appear in the load voltages. Equation (11) is valid no matter the type of sags/swells present in the grid voltages (threephase, two-phase, single-phase or two-phase-to-ground), showing the ability of strongly attenuating the zero-sequence load voltage. |Zt + Zc //Zm| |Zl| holds for a certain range of frequencies, making it possible to attenuate zero sequence voltage disturbances in this range of frequencies
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
