Transformerless dynamic voltage restorer

The feasibility of achieving dynamic voltage restoration without the use of the injection transformer is investigated. The configuration of a proposed transformerless dynamic voltage restorer (DVR) features separate energy storage capacitors for phase-to-phase isolation, cascaded switches/inverters for the voltage boosting functions and a dynamic energy replenishing charging circuit. Comparison of the scheme with the conventional DVR is conducted in terms of voltage regulation property, power losses, reliabilities, costs and ride-through capabilities. The transformerless DVR is seen to be advantageous over the conventional DVR in many aspects. Simulation results also demonstrate the effective dynamic performance of the DVR scheme.