基于希尔伯特-黄变换的高压直流线路行波保护

HVDC traveling wave protection based on Hilbert-Huang transform

为了提高直流输电线路保护的动作可靠性和准确性,采用希尔伯特-黄(Hilbert-Huang)变换分析了故障下行波波形,结合直流线路低电压等综合判据构成了一种直流输电行波保护新方案。该保护能利用对信号的经验模态分解更准确地提取故障行波特征,然后通过求行波信号高频固有模态函数分量的瞬时频谱分析提取故障特征、形成故障判据。该保护原理不但具有传统行波保护的所有优点,还具有抗干扰能力,可以用于捕捉直流输电线路故障时的行波头到达时间,对于直流输电故障定位具有一定实用价值。实际故障录波及仿真验证表明,该保护可以保证区内高阻接地正确动作.且在逆变侧交流短路故障或换相失败时不误动。

In order to improve the reliability and accuracy of the HVDC traveling wave protection, a new high-speed HVDC line protection using Hilbert-Huang transform technique is described. The fault traveling wave characteristic is first extracted by empirical mode decomposition （ EMD ） method. The protection criterions for HVDC lines are proposed based on the instantaneous frequency spectrum of the highest frequency intrinsic mode function （IMF）. Simulations and field fault recorder analysis are carried out for testing proposed criterions. The influences of similar faults are also discussed. The protection can detect HVDC line fault well and separate HVDC line fault clearly from similar transients, such as commutation failure or AC single phase fault.