基于测量波阻抗的母线保护新方法

A Novel Approach for Busbar Protection Based on Measured Surge Impedance

为避免电流互感器饱和对母线保护的影响,提出一种基于测量波阻抗的母线保护新方法:对母线区内、外故障的情况进行了理论分析,当发生母线区内故障时,所有线路的测量波阻抗的极性均为负,幅值近似相等;当母线发生区外线路故障时,故障线路的测量波阻抗的极性为正,且其幅值远小于非故障线路的测量波阻抗的幅值;通过对母线上各线路的测量波阻抗的极性和幅值进行比较即能判断母线故障类型。此外,还对该母线保护新方法的实现方案进行了探讨,得到了可行的保护实现方案。理论分析及EMTP仿真表明,基于测量波阻抗的母线保护方法基本不受故障类型、故障过渡电阻、故障距离和故障初始角的影响,且能体现行波的本质,保护方法可靠、有效。

To avoid the influence of current transformer saturation on bus-bar protection, a measured surge impedance based approach for busbar protection is proposed. The theoretical analysis on the faults occurred inside and outside the busbar protection zone shows that when the fault inside the protection zone occurs the polarity of all measured surge impedances of all transmission lines are negative and their amplitudes are approximately equal, when the fault outside the protection zone occurs the polarity of all measured surge impedance of all transmission lines are positive and their amplitudes are far less than the amplitudes of measured surge impedances of non-faulty transmission lines, thus by means ofcomparing the polarities and amplitudes of measured impedances of all transmission lines connected to the busbar the fault type occurred on busbar can be judged. Besides, the implementation of the proposed new approach for busbar protection is discussed and a feasible scheme to implement the proposed approach is achieved. Results of both theoretical analysis and simulation of EMTP show that the proposed approach based on measured surge impedance is basically not affected by fault types, transition resistance, fault position and initial phase angle by which the fault occurs, so this approach is reliable and effective.