The study of grid integration analyses the framework for evaluating a power system with high penetration levels of power electronics coupled renewable energy sources (RES). These renewables are integrated to power grid through power electronics converters in both Grid following (GFL) mode and grid forming (GFM) mode. In GFL mode phase locked-loop (PLL) is used for integrated in which converter is controlled as current source inverter. PLL dynamics might have a negative impact, operated with weak ac-system. In GFM mode integration with grid is achieved without PLL, and converter is controlled as voltage source converter which has capability to overcome the issues with GFL control mode. We are working on GFM control multilevel converter topologies with weak grid system.