A soft start-up method for DC micro-grid based on improved two-level VSC with DC fault ride-through capability

For the black start-up of DC micro-grids, three-phase charging resistors are required to limit uncontrollable surge current. The main drawback this method is difficulty in determining appropriate resistance value achieve a rapid and current with change grid parameters. To address problem, article proposes soft for micro-grid based on an improved two-level voltage source converter (VSC). Specifically, silicon controlled rectifier anti-parallel diode added each up-bridge-arm VSC. By conducting dynamic control strategy firing angle SCRs, can always be maintained near given start-up. Moreover, VSC has fault ride-through capability. simulation results PSCAD/EMTDC provided validate feasibility proposed method.