A novel protection scheme for turn-to-turn fault of thyristor controlled transformer controllable shunt reactor

Thyristor controlled transformer controllable shunt reactor (TCTCSR) with advantages of rapid response and continuously adjustable capacity is the preferable choice for reactive power control in EHV/UHV power system. But the protection scheme of TCTCSR is rarely studied. This paper addresses a problem in the application of traditional current differential protection against turn-to-turn faults where the traditional protection scheme may have less sensitivity or even refuse to operate in certain fault cases. Theoretical analysis is presented in this paper and three-phase fundamental zero-sequence component of CtrW as criteria to detect turn-to-turn faults is proposed to overcome the problem in traditional protection scheme. Finally, the setting value of the proposed method and its impact factors are discussed.