B. Tousi, M. Farhadi-Kangarlu, M. Farzinnia,
Volume 15, Issue 3 (9-2019)
Abstract
In this paper a new topology for Dynamic Voltage Restorer (DVR) with high frequency link is proposed. This topology is able to compensate different types of voltage disturbances such as voltage sag, voltage swell and voltage harmonics. According to the obtained equations, this topology operates as a controllable current source to charge the series capacitor. Due to using High Frequency Transformer (HFT), the volume and the weight of the proposed DVR is decreased in comparison with conventional DVRs. This topology contains two ac/ac converters which are using in the input and output of the device. The absence of DC link capacitors and storage elements is the other advantage of using the proposed structure. In order to verify the claimed features, the proposed topology has been simulated by PSCAD/EMTDC software and examined under several disturbance conditions. In addition, an experimental prototype has been designed and tested. The results of the simulation and experimental cases are presented.
S. A. Rahman, S. Birhan, E. D. Mitiku, G. T. Aduye, P. Somasundaram,
Volume 17, Issue 4 (12-2021)
Abstract
Aim of this paper is to attain the highest voltage sag and swell compensation using a direct converter-based DVR topology. The projected DVR topology consists of a direct converter with bidirectional switches, a multi winding transformer with three primary windings and secondary winding and a series transformer. When voltage swell occurs in a phase, the same phase voltage can be utilized to mitigate the swell as huge voltage exists in the phase where swell has occurred. So it is possible to mitigate an infinite amount of swell. In all the DVR topologies, the converter is only used to synthesize the compensating voltage. The range of voltage sag mitigation depends upon the magnitude of input voltage available for the converter. If this input voltage of the direct converter is increased, then the range of voltage compensation could also be increased. Input voltage of the direct converter is increased using the multi winding transformer. The direct converter is synthesizing the compensating voltage. This compensating voltage is injected in series with the supply voltage through the series transformer and the sag is mitigated. In this proposed topology, the input voltage for the direct converter is increased by adding the three phase voltages using a multi winding transformer. Thus the voltage sag compensating range of this topology is increased to 68% and the swell compensating range is 500%. Ordinary PWM technique has been used to synthesize the PWM pulses for the direct converter and the THD of the compensated load voltage is less than 5%. This topology is simulated using MATLAB Simulink and the results are shown for authentication.
