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Suonan J.,Xi'an Jiaotong University | Zhang J.,Northwest China Power Dispatch and Communication Center | Liu L.,Xi'an Jiaotong University | Tan S.,Xi'an Jiaotong University | Yang Z.,Xinxiang Electrical Power Supply Corporation
Hsi-An Chiao Tung Ta Hsueh/Journal of Xi'an Jiaotong University | Year: 2010

The traditional distance protections applied to the AC-DC power system usually induce transient overreach, especially for the Inverter commutation failure in DC system. It is found that the transient overreach in AC-DC power system is due to fault transient signals containing a large number of low-frequency components of the slow decay and non periodic components and high frequency components. The voltage and current of tuning point based on distributed-parameter model are calculated, and the equations for identifying the distance between tuning point and the point of failure by R-L model are established to put forward a protection scheme. The simulations show the ability for distinguish internal fault from external fault and preventing transient overreach.

Song G.-B.,Xi'an Jiaotong University | Liu Z.-L.,Xi'an Jiaotong University | Su X.-H.,Northwest China Power Dispatch and Communication Center | Zhang J.-K.,Xi'an Jiaotong University | And 2 more authors.
Dianli Xitong Baohu yu Kongzhi/Power System Protection and Control | Year: 2010

This paper analyzes a maloperation event of longitudinal zero-sequence protection in north-west 330 kV lines, caused by zero-sequence mutual inductance between lines. By deeply analyzing the link between power network structure and maloperation of longitudinal zero-sequence protection from theoretical analysis and quantitative analysis, it sums up behaviors of longitudinal zero-sequence protection under different running situations of double-circuit lines, concludes that the reason for maloperation of protection is weak current and strong magnetic contact of lines, and points out that the necessary condition for maloperation is the reverse of zero-sequence voltage on both sides. In order to solve the weak current and strong magnetic problem, zero-sequence direction components based on fault type are used instead of zero-sequence direction components. Recording data analysis proves the effectiveness and accuracy of this measure.

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