一种基于简化能量比的直流线路故障区间定位方法

高压直流输电线路及其边界对故障暂态信号高频分量都有明显的衰减作用,这一故障特征被广泛运用于暂态保护,且有研究显示,相较于线路边界,长线路对故障暂态高频分量的衰减作用可能更大,为避免这种情况引起的保护误动,目前常用的故障特征提取方式为利用不同尺度的小波变换获取暂态信号能量比。但基于小波变换的暂态保护存在算法相对复杂,基波选取模式不统一等问题。因此提出一种新的比值算法,针对故障暂态信号中的能量比,用全电流代替低频分量,简化了直流线路故障信息处理过程,由此设计出了新的直流线路故障定位方法,并且利用该判据可直接实现故障极判断。在MATLAB中进行了大量仿真验证,证明该保护算法可以正确反映出故障特征,逻辑简单,并且能够迅速可靠动作。

A Fault Location Method for DC Line Based on Simplified Energy Ratio

HVDC transmission lines and their boundaries have obvious attenuation effect on the high frequency components of fault transient signals. This fault feature is widely used in transient protection. Studies have shown that compared with line boundaries, the attenuation effect of long lines on the high frequency components of fault transient may be greater. In order to avoid the protection malfunction caused by this situation, the commonly used fault feature extraction methods are currently used. In order to obtain energy ratio by using different scales of wavelet transform. However, the algorithm of transient protection based on wavelet transform is relatively complex and the mode of fundamental wave selection is not uniform. Therefore, a new ratio algorithm is proposed to simplify the process of fault information processing for DC lines by replacing the low frequency component with the full current for the energy ratio of fault transient signals. A new fault location method for DC lines is designed, and the fault pole can be judged directly by using this criterion. A lot of simulation results in MATLAB prove that the protection algorithm can correctly reflect the fault characteristics, has simple logic and can act quickly and reliably.