A novel dual hysteresis controller for the management of a three phase dynamic voltage restorer.

In this work a novel control scheme for the three-phase dynamic voltage restorer has been proposed and validated. The proposed control strategy guarantees the source current waveform to be sinusoidal and at near unity power factor. Further, the voltage sag and swell occurring in the source are overcome and the load gets a smooth power supply at a voltage closer to the rated voltage even in the face of voltage sag or swell occurring in the source. The proposed system uses a power factor corrected front end rectifier that regulates a defined voltage in a DC link. The DVR derives power from the DC link. The PFC rectifier and the DVR converter both are controlled by individual PI and hysteresis current controllers. Further the control system has been adopted in per phase method with actual current estimation system for each phase of the rectifier and the DVR sides done individually. The main advantage of the proposed system is that it does not require the usually required DQ transformation scheme. The proposed idea has been proved to be suitable for balanced and unbalanced loads. The proposed idea has been validated with dynamic simulations carried out in the MATLAB SIMULINK environment and with a scaled down experimental prototype.