Restaurador dinâmico de tensão utilizando transformadores com enrolamentos abertos e inversores com barramentos isolados.

Abstract

There are several types of disturbances that can cause a malfunction of an electrical system, which characterizes it as a low power power source. Among these problems, we can highlight the voltage sags and swells. One device able to mitigate such problems is the dynamic voltage restorer (DVR). Such a device can compensate for harmonic distortions, phase angle jumps and possible network imbalances so that the load is not affected. This work presents a DVR structure obtained through the serial connection of two three-phase inverters. Such an arrangement aims to power the DVR's injection transformers with their windings open. This inverter topology is commonly used in the drive of machines with terminals to open windings, known in the literature as OEW (Open End Winding). In this work, the topology under study encompasses some aspects such as: (i) DVR model and configuration, (ii) PWM Water switching strategy, (iii) basic operating principles and (iv) comparative studies with respect to conventional structure. The main advantages of the proposed structure compared to conventional are: (i) reduced harmonic distortion (operating at the same switching frequency), (ii) reduced losses in the converter (operating at the same level of harmonic distortion), (iii) less (stress) on the power switches and (iv) fault tolerance. The proposed DVR system is suitable for applications in medium and high voltage systems since it is capable of generating voltages with higher numbers of levels, characterizing it in a multilevel structure. The studies done are validated through simulation and experimental results.