INVESTIGATION OF A MODULAR HIGH-VOLTAGE DC-DC CONVERTER FOR THE INTEGRATION OF INDUSTRIAL RENEWABLE ENERGY SOURCES INTO THE POWER GRID

This paper presents a modular high-voltage DC-DC converter designed for integrating industrial renewable energy sources (RES) into HVDC transmission systems. Using a modular multilevel converter (MMC) architecture, the design offers scalability, fault tolerance, and efficiency exceeding 98%. The converter achieves high voltage conversion ratios—up to 700 V output from 20–40 V input—by connecting low-voltage submodules in series, reducing component stress and electromagnetic interference. Advanced control strategies, including pulse-width modulation and circulating current suppression, ensure stable power flow. Simulations in MATLAB®/Simulink® validate a sliding mode control (SMC) approach, maintaining output voltage at 170 V despite input variations, with rapid transient response (0.05 s) and minimal voltage deviation (±2%). Under dynamic load changes (50–100%), SMC outperforms conventional PI and LAD controllers, maintaining voltage deviation within ±1.5% and faster recovery (~0.03 s). These results demonstrate the converter’s robustness in regulating voltage and handling disturbances typical of renewable energy inputs and load fluctuations. The system’s modularity enables flexible adaptation to applications such as offshore wind farms and photovoltaic plants, facilitating the efficient and resilient integration of Renewable Energy Sources (RES) into existing High-Voltage Direct Current (HVDC) grids. This work highlights the potential for enhancing power transmission efficiency and stability amid growing renewable penetration.