Solar-tied five-level reduced switch multilevel inverter-based dynamic voltage restorer for medium-voltage distribution systems

This paper introduces a multilevel inverter with a reduced switch count, integrated with a Photovoltaic (PV) system functioning as a Dynamic Voltage Restorer (DVR). The inverter, known as the Transistor Clamped H-Bridge (TCHB) inverter represents a novel topology of multilevel inverters (MLIs). Compared to conventional inverter designs that provide the same output quality, the proposed inverter reduces the number of components and shows lower power losses. In this study, a 5-level TCHB-MLI based DVR is examined for its application in medium voltage (MV) networks (11kV). The PV system is designed to deliver maximum power to both the grid and the load using the Perturb and Observe Maximum Power Point Tracking (MPPT) method. A new control technique, based on the Unit Vector-based PLL-less Synchronous Reference Frame theory, is employed to implement the DVR. The performance of the proposed DVR is assessed under different voltage quality issues, including voltage harmonics, imbalance, sag, swell, and their combinations, using MATLAB/SIMULINK software. The experimental validation of the results is carried out using a real-time digital simulator.