基于小波变换的HVDC线路行波电流极性比较式方向保护

Directional Protection Based on Traveling Wave Current Polarity Comparison Using Wavelet Transform on HVDC Line

首先分析了高压直流输电线路行波保护的特点,然后对目前工程上普遍采用的行波保护方案进行了具体分析和仿真。通过对仿真结果的分析,指出了现有的保护原理产生误动的具体原因是由于保护原理采用了微分等运算易受噪声的影响以及判据选取的数据均为瞬时值,在计算时选择的计算点的数值直接影响了判据的结果。在极性比较式保护方案分析的基础上,充分考虑到直流线路自身的特点,提出利用直流输电工程中现有的保护通道,来构成基于小波变换的电流行波极性比较式方向保护的方案,用以解决直流线路保护的问题。仿真结果表明这种基于小波变换的保护方案能够快速可靠地区分直流线路区内和区外故障,为构造新的直流线路高速保护提供了理论依据。

The paper firstly analyzes the characteristics of HVDC line traveling wave protection, then concretely analyzes and simulates the schemes of traveling wave protection, which are commonly used in projects at present. According to the analyses of the simulation results, it has been pointed out that the reasons why actual protection systems often give false alarms is that the protection scheme uses some operations, such as the differential operation, which are sensitive to noises. Based on the analyses of the directional protection scheme and adequate consideration of the characteristics of HVDC line, the paper proposes the setting value protection scheme of polarity comparison using the wavelet transform. The results of simulation show that the scheme can effectively distinguish between the inside and outside faults. The proposed scheme can provide a standard for HVDC line rapid protection.