一种利用衰减非周期分量的UHVDC线路故障选极元件

针对一极线路遭受故障时,另一极线路会耦合到很大的电压突变率和电流变化率,甚至可能引起健全极线路的保护动作的问题,提出一种利用衰减非周期分量的UHVDC线路故障选极元件。对特高压直流输电线路故障暂态特征时域和频域的分析发现,直流线路整流侧保护测量处故障极的衰减非周期分量大于非故障极的衰减非周期分量,由此构成UHVDC故障选极判据。通过小波变换分解两极线路故障电流,并在频带0~20Hz进行重构以提取故障电流的衰减非周期分量,根据两极线路衰减非周期分量能量的比值进行故障选极。大量的仿真结果表明,该方法对于不同的故障位置、过渡电阻以及故障类型来说具有较强的鲁棒性,在各种工况下均能可靠快速地选出故障极,不受数据同步的影响,门槛值易整定,具有工程现场意义。

UHVDC line fault selective component using attenuating non-periodic component

In order to address the problem that when one pole line suffers from a fault,the other pole line will be coupled to a large voltage mutation rate and current variation rate,and may even cause the protection action of the sound pole line,a UHVDC line fault pole selection element using the attenuation acyclic component was proposed.The analysis of the UHVDC transmission line fault transient characteristics of the time and frequency domain found that the DC line rectifier side of the protection measurement at the attenuation acyclic component of the fault electrode is greater than the attenuation acyclic component of the non-fault electrode,which constitutes the UHVDC fault electrode selection criterion.In the wavelet transform the two-pole line fault current was decomposed,and was reconstructed in the frequency band 0~20 Hz to extract the attenuation acyclic component of the fault current,and the fault poles were selected according to the ratio of the attenuation acyclic component energy of the two-pole line.A large number of simulation results show that the method has strong robustness for different fault locations,transition resistances,and fault types,and can reliably and quickly select the fault poles under various operating conditions,without the influence of data synchronization,and the threshold value is easy to tune,which has engineering field significance.