Real-time implementation of transformerless dynamic voltage restorer based on T-type multilevel inverter with reduced switch count

This paper presents T-type multilevel inverter topology-based dynamic voltage restorer (DVR) with reduced switch count. In medium voltage and high-power applications, two-level voltage source inverters are insufficient because of more voltage stress on switches, large dv/dt, size, and cost of the filter. To overcome these problems, multilevel inverter-based DVR is suitable, which can be directly connected to the medium voltage distribution system without injection transformer. In addition, the control of the DVR is implemented by abc to dq controller. The voltage compensation capability of the proposed DVR is enhanced by employing the in-phase compensation technique with reduced carrier pulse width modulation scheme, and also the total harmonic distortion(THD) in the load voltage is reduced. The design and analysis of the proposed system are discussed, and its performance is validated in MATLAB/Simulink and in the OPAL-RT real time processor.