Multilevel Cascaded Medium-voltage Convertor for Direct Grid Integration of Renewable Energy Systems through a High – Frequency Link

— Recent advances in solid-state semiconductors have led to the development of medium voltage power converters which could obviate the need for the step-up transformers of renewable power generation systems. The modular multilevel cascaded converters have been deemed as strong contenders for the development of medium-voltage converters, but the converters require multiple isolated and balanced dc supplies. In this paper, a high frequency link multilevel cascaded medium -voltage converter is proposed. The common inherently minimizes the voltage imbalance and common mode issues. An 11-KV system is designed and analyzed taking into account the specified system performance, control, complexity, cost, and market availability of the power semiconductors. To verify the feasibility of the proposed system, a scaled down 1.73KVA MATLAB/SIMULINK platform with a modular five-level cascaded converter and nine level inverter is developed and explored in this paper which converts a 210 V into three-phase 1 KV rms 50 Hz ac.