The Research and Application of open phase monitoring and protection system in nuclear power plant based on flexible optical current transducer

This paper introduces several cases of open phase fault in nuclear power plants and introduces the requirement of monitoring and protection of open phase fault. Through simulation analysis, the electrical characteristics of the power plant electrical system, especially the high voltage side of the auxiliary transformer, are obtained when the fault happened. Based on the simulation results, a new $\mathbf{t}$ echnical solution is proposed, which uses the optical current transformer (FOCT) to detect the current of each phase and distinguish the open phase by the non-current or capacitive current criterion. The dynamic model test and field operation data show that the use of this system can be sensitive to respond to the phase failure in nuclear plants.