H-bridge multilevel voltage source converter for direct grid connection of renewable energy systems

The conventional approach based on low-voltage converter with power frequency transformer is commonly employed for grid connection of offshore renewable power generation systems. Because of the heavy weight and large size of the transformer, the system can be expensive and complex for installation and maintenance. As an alternative approach to achieve a compact and light direct grid connection, a high-voltage converter using series connected H-bridge (SCHB) multilevel converter topology is proposed in this paper. Since the SCHB converter requires a large number of isolated and balanced DC supplies, a high frequency transformer link is employed to couple the SCHB to the single low voltage DC supply. This paper presents the design and simulation of the proposed system.