Power grid fault will cause the frequency and voltage fluctuation of the nuclear power plant

which will directly affect the operation status of the coolant pump and the heat dissipation blade of the nuclear power unit. When the fluctuation degree exceeds the maximum allowable range of the nuclear power equipment

may cause the nuclear power plant damage. In order to study the operation status of large nuclear power plant under the condition of grid fault

this paper studies the nuclear power plant in a certain area

and builds a 500 kV grid model including PWR nuclear power plant on PSCAD/EMTDC platform. The detailed model of nuclear power plant including the core

steam generator

steam turbine module

etc.

the model can reflect the power grid failure in the case of nuclear power plant internal dynamic characteristics. By analyzing the influence of voltage and frequency disturbance on the nuclear power unit

the disturbance threshold of the safe operation of the nuclear power unit is given. The equipment protectionstrategy of the three-phase short-circuit fault under the grid is put forward

which is safe and stable for the nuclear power plant running further research laid the foundation.