Research On The Digital Protection For Extra High Voltage Shunt Reactor

When a shunt reactor is switched on, there will be a high level DC current, which may cause the saturation of the current transformer (TA) and may cause the mis-operator of the differential protection. So this paper presents the protection scheme of multi-stage reactor differential protection considering different transient characteristic of TA, transient TA saturation and intermittent TA second loop break. The differential protection is only restrained by neutral point current to improve the sensitivity in case of internal fault. In order to solve the contradiction between sensitivity and reliablity of turn-to-turn fault protection more efficiently, principle of turn-to-turn fault protection is also presented, which uses an adaptive compensated zero sequence direction relay and judges all the electrical characteristics of the protected reactor. The complete protection configuration scheme of a shunt reactor is also introduced according to the characteristics of the shunt reactor. Dynamic simulation experiments show that the new protection scheme is correct and practicable. In the end, features of the protection devices, non electrical quantity protection and its reliability, protection setting calculation are presented.