The increasing use of voltage variation sensitive loads in industrial applications nowadays has brought a real concern about interruption costs and damages in complex production lines. This paper presents a power-electronic–based device which compensates voltage sags, restoring the load voltage to acceptable values through a series connected injection transformer. The ratings and power requirements of a low-power voltage sag compensator, also known as Dynamic Voltage Restorer (DVR) are derived, as well as its deadbeat control algorithm implemented in a Digital Signal Processor (DSP). Finally, simulation and experimental results of a 5-kVA prototype are presented.

This paper presents the analysis of subway thyristor controlled rectifier substations. The classical analysis developed for 12 pulse diode bridges is adapted to consider thyristors and simulated. This simulation considers the simultaneous operation of several rectifiers connected to the same distribution network. Simulation results show that the harmonic impact of these rectifiers on the distribution network is considerable and is amplified by the cable capacitances. Measurements taken on a 12 pulse diode rectifier substation confirm this amplification effect

The electric engineering development has provided a more intense use of today's equipment with greater efficiency. But, often, such equipment cause distortions in the network's voltage and current waveforms and also it is sensitive to fluctuations of the network itself. Active filters constitute a feasible technological option for the mitigation of distortions and fluctuations, so as to improve the quality of energy and the development of mitigating technologies for harmonic distortions, through series and shunt voltage sources created by power electronics devices (DVR-dynamic voltage restorer). This project has been developed a miniDVR prototype to: firstly, recompose the voltage transients present and operate as a voltage active filter, and secondly, act also compensating part of the reactive load, in this way, improving the voltage control. This device is in its final test phase at the EPUSP laboratory with the transient recomposition function (sag/swell and voltage harmonics).

The power electronics-based FACTS technology, applied to transmission systems, can also be useful in distribution systems. To this end, it is necessary to follow a consolidation procedure of the utilization and performance of this technology so that they can be applied with no risks. The application of this technology will bring along several benefits for the expansion of the distribution systems, namely: flexibility in the networks' utilization, interconnection of feeders allowing the manipulation of energy blocks without the need of disconnecting them, continuous adjustment of reactive power during the operation, and a dynamic control of the power flow. In this work, two aspects for the application of this technology in distribution systems, will be studied. The first aspect is referred to the application of a FACTS device that acts as a series compensator and which offers the possibility of making feasible the continuous control of the series reactance. The second aspect is referred to its utilization in the interconnection of two feeders, where active power between them is dynamically controlled. The simulation program used was the ATP (alternative transients program).

The electric engineering development has provided a more intense use of today's equipment with greater efficiency. But, often, such equipment cause distortions in the network's voltage and current waveforms and also it is sensitive to fluctuations of the network itself. Active filters constitute a feasible technological option for the mitigation of distortions and fluctuations, so as to improve the quality of energy and the development of mitigating technologies for harmonic distortions, through series and shunt voltage sources created by power electronics devices (DVR-dynamic voltage restorer). This project has been developed a mini-DVR prototype to: firstly, recompose the voltage transients present and operate as a voltage active filter, and secondly, act also compensating part of the reactive load, in this way, improving the voltage control. This device is in its final test phase at the EPUSP laboratory with the transient re-composition function (sag/swell and voltage harmonics).