The adaptive unit transverse differential protection based on the fault contributed current

摘要

A new adaptive unit transverse differential protection based on the fault contributed zero-sequence current for the generator is introduced in this paper. The performance of the conventional unit transverse differential protection is usually greatly affected by the unbalanced current. To overcome this disadvantage, the fault contributed zero-sequence current is applied to remove the influence of the pre-fault current. At the same time, analysis results show that the unbalanced current always present the linear relationship with the stator current. According to that, the proposed scheme can change the setting value adaptively, which improves the protection sensitivity for the generator light internal fault. For the external fault, the scheme can enhance the protection reliability because it ensures a high restraint current. The new scheme is developed and the practical implementation of the protection equipment is also demonstrated. The test results show that the proposed approach is successful in detecting the generator internal fault, and could have high sensitivity and selectivity.