Due to the high concentration of electricity generation and distribution in the floating nuclear power plant grid-source direct connection system, the generator stator ground fault protection is affected by the direct connection power grid. Traditional protection methods cannot distinguish the fault direction and are difficult to guarantee the extreme safety requirements of the nuclear islands. This paper analyzes the system ground fault, points out the limitations of the existing generator stator ground protection methods, and proposes an adaptive form of generator stator ground fault protection method. Based on the phase-current differential, the method can effectively distinguish the faults inside or outside the generator, which can also form the protection criterion and action strategies according to the fault degree. It can trip the generator smoothly under slight fault conditions, ensuring the safe and stable operation of the floating nuclear power plant. Simulation in PSCAD/EMTDC proves that the proposed method can effectively realize the selective coordination of the ground fault protection for the grid-source direct connection system.

adaptive form, floating nuclear power plant, phase-current differential, grid-source direct connection system, generator stator ground fault protection