一种TSDF判别算法的自适应阻抗保护研究

Research on Adaptive Impedance ProtectionBased on TSDF Discriminant Algorithm

阻抗保护Ⅲ段已被确定为电力系统级联故障的原因之一。由于三相故障的对称现象,所以一般很难在电力系统低频振荡时检测出来,造成保护装置误动。针对这个问题,利用一种基于Matrix Pencil(MP)方法的瞬态监督检测函数(Transient Supervisory Detection Function,TSDF)检测低频振荡过程中发生的三相故障,得出该自适应阻抗保护方法,可以快速、便捷、可靠的检测出电力系统低频振荡时发生三相故障的结果。该算法通过比较检测指数g和自适应阈值gth去检测判断电力系统是否发生三相故障。仿真结果表明,其所提算法在仅振荡或故障的单一情况下,和在振荡且分别发生区内外故障的两种情况下,可以保证保护装置可靠动作。

The impedance protection section III has been identified as one of the causes of cascading faults in the power system.Due to the symmetrical phenomenon of three-phase faults,it is generally difficult to detect them during low-frequency oscillations in the power system,resulting in misoperation of the protection device.To address this issue,a Transient Supervisory Detection Function(TSDF)based on Matrix Pencil(MP)method is used to detect three-phase faults that occur during low-frequency oscillation.This adaptive impedance protection method can quickly,conveniently,and reliably detect the results of three-phase faults that occur during low-frequency oscillation in the power system.This algorithm detects and judges whether a three-phase fault has occurred in the power system by comparing the detection index g and the adaptive threshold g th.The simulation results show that the proposed algorithm can ensure the reliable operation of the protection device in a single case of oscillation or fault,and in two cases of oscillation and separate occurrence of internal and external faults.