Dynamic voltage restorer using ultra storage capacitor

Voltage Sag is a crucial power quality problem faced by the utility industry which has resulted in increased attention. This paper presents the Dynamic Voltage Restorer (DVR) for mitigating the effect of voltage sag which gives the solution to this problem. The dynamic voltage restorer compensation capability mainly depends upon the maximum voltage injection ability and the amount of stored energy available within the restorer. This paper proposes Z-source inverter based DVR in order to enhance the voltage restoration property of the device. By controlling the shoot-through duty cycle, the Z source inverter system provides ride through capability during long duration voltage sags, reduces line harmonics, improves power factor and high reliability. The control system of the proposed DVR is based on Hysteresis Voltage control that has a very fast response, simple operation and variable switching frequency. In this paper, the conventional storage unit is replaced by ultra capacitor. The proposed system is simulated using Matlab-Simulink tool and the simulation results are verified.