基于电压行波波形特征的柔性直流输电线路雷击识别方法

柔性直流输电系统的线路主保护速动性要求极高，线路受雷击干扰后引入大量高频暂态信号易引发线路保护误动作。针对此问题，首先根据行波的传播规律分析雷击后线路电压行波特征，得出雷击干扰与故障的特征差异。雷击干扰时，暂态过程中电压行波经线路边界反射后波头极性不发生改变，行波波头到达线路边界的时间间隔大。雷击故障时，电压行波经故障点反射后波头极性发生改变，行波波头到达线路边界的时间间隔小。然后，根据电压行波波形特征差异提出长短窗结合的雷击干扰识别方法。最后，利用PSCAD/EMTDC电磁暂态仿真软件对所提方法进行验证。结果表明，所提出的雷击干扰识别方案能够快速、可靠、准确地识别雷击干扰与故障情况，不受雷击位置、线路参数、雷电流参数和噪声的影响。

Lightning interference identification method based on voltage traveling wave waveform characteristics for flexible DC transmission lines

The speed requirement for the main protection of the MMC-HVDC system is extremely high. The introduction of a large number of high-frequency transient signals after the line is disturbed by lightning strikes can easily lead to misoperation of line protection. To solve this problem, this paper first analyzes the characteristics of a line voltage traveling wave after lightning strike according to the propagation law of traveling waves. The characteristic difference between lightning disturbance and fault is obtained. When lightning disturbance occurs, the polarity of the wave head does not change after the voltage traveling waves is reflected by the line boundary during the transient process, and the time interval between the traveling waves head and the line boundary is large; when the lightning fault occurs, the polarity of the voltage traveling waves changes after being reflected by the fault point, and the time interval between the traveling waves head and the line boundary is small. Then, based on voltage traveling waveform features, a lightning interference identification method combining long and short windows is proposed. Finally, the proposed method is validated using PSCAD/EMTDC electromagnetic transient simulation software. The results show that the proposed lightning interference identification scheme can quickly, reliably, and accurately identify lightning interference and fault conditions, independent of the location of lightning strikes, line parameters, lightning current parameters, and noises.