基于Hilbert-Huang变换的HVDC线路保护

为了准确地判定HVDC输电线路的故障类型和对故障距离进行定位,应用PSCAD搭建单极12脉直流输电系统等效模型,对直流线路区内故障及区外对线路保护性能有影响的各种故障进行仿真。应用HilbertHuang变换方法对故障电压信号进行分析,提取了行波的波头,从而确定故障发生时刻。分析直流滤波器和平波电抗器所具有的固有滤波特性,由此形成了以频率和能量为基础的故障判别方法。在确定为区内故障后,采用D型双端行波定位方法根据检测到的故障时刻可以准确地对故障距离进行定位。并提出了基于HHT方法的HVDC线路保护判别式和动作逻辑。仿真和计算结果表明,该保护方法不仅可以准确地判别故障类型和故障距离,且在过渡电阻较大的情况下对保护性能没有影响。

HVDC Transmission Line Protection Based on HHT

In order to determine the type of HVDC transmission line fault and locate the fault distance accurately.Build a monopole 12 pulse HVDC model based on PSCAD, then simulate faults inside DC line and the faults outside the DC line, that could influence the line protection performance. Take analysis of the voltage signal of faults based on HHT, extract wave head of traveling wave, then determine the failure time. Take analysis of the intrinsic filtering characteristics of smoothing reactor and DC filter, then forming a fault discrimination method based on frequency and energy. If the fault occurred inside the DC line, according to the failure time that has been detected, could calculate the distance of fault with the application of tow sides traveling wave locating method. And proposed HVDC transmission line protection discriminants and action logic. Through simulation calculation results show that the protection method not only could discriminate the fault occurred inside the DC line, but also could fault distance accurately. In case of large transition resistance did not affect the protection performance.