基于行波波头瞬时频率的输电线路故障无通道全线速动行波保护

Traveling wave instantaneous frequency based non-unit high speed protection for transmission line

提出一种利用区内外初始行波信号的频率差异来区分内外部故障的快速保护原理。首先,详细分析母线杂散电容和阻波器对故障行波的影响;然后,对初始电流行波进行希尔伯特变换(HHT变换)得到各频段的时频图,提取初始电流行波突变点频率,利用行波波头瞬时频率差异作为判据区分内外部故障。理论分析和仿真结果表明,该方法动作快,不易受故障类型、故障角度和故障接地电阻的影响,不存在保护死区,是一种简单有效的高压线路保护方法。

A rapid protection principle with the frequency difference of initial traveling-wave distin-guishing internal and external fault was proposed in this paper.Firstly,the influence of wave trapper and bus capacitance on the initial traveling-wave was analyzed.And then the time-fre-quency graph of initial current travelling waves was obtained by Hilbert-Huang Transform.The relationship of the catastrophe point frequency and wave trapper frequency was used to distin-guish external and internal fault.Theoretical analysis and simulation results showed that the method has advantages of high speed and little influence by the fault types,fault point and grounding resistance,and it is simple and useful for extra-high-voltage transmission line protec-tion without protection dead zone.