A novel scheme to identify symmetrical faults occurring during power swings

作者：Lin Xiangning^*; Gao Yan; Liu Pei

来源：IEEE Transactions on Power Delivery, 2008, 23(1): 73-78.

DOI：10.1109/TPWRD.2007.911154

• change rate of power
• crossing blocking
• distance protection
• instantaneous electrical quantities
• power swing blocking

A novel, fast unblocking scheme for distance protection to identify symmetrical faults occurring during power swings has been proposed in this paper. First of all, the change rate of three-phase active power and reactive power being the cosine function and the sine function with respect to the phase difference between the two power systems during power swings has been demonstrated. In this case, they cannot be lower than the threshold of 0.7 after they are normalized. However, they will level off to 0 when a three-phase fault occurs during power swings. Thereafter, the cross-blocking scheme is conceived on the basis of this analysis. By virtue of the algorithm based on instantaneous electrical quantities, the calculation of the active and reactive power is immune to the variation of the system power frequency. As the integration-based criterion, it has high stability. Finally, simulation results show that this scheme is of high reliability and fast time response. The longest time delay is up to 30 ms.

• 出版日期2008-1
• 单位三峡大学; 华中科技大学