基于边缘检测的大规模风电场送出线路纵联保护算法

由于风电出力的波动及送出线路发生故障时故障电流的频偏特性，风电场送出线路纵联保护灵敏度下降甚至拒动，因此提出了基于边缘检测的风电场送出线路纵联保护算法。通过将风电场送出线路两侧采集到的电流构造为矩阵形式，并使用Sobel算子进行边缘检测，从而确定电流采样值变化大的部分。然后通过所识别到的线路两侧电流采样值变化大的部分计算平均梯度幅值并与整定值相比较，实现区内故障和区外故障的快速识别。最后通过PSCAD/EMTDC搭建了大规模风电场送出系统模型，验证了所提算法的适用性、速动性及抗过渡电阻能力。与现有送出线路的纵联保护相比，所提方法在风电场弱出力的情况下仍适用，且动作速度更快。

Pilot protection algorithm of large-scale wind farm outgoing transmission line based on edge detection

Due to the fluctuation of wind power output and the frequency offset characteristics of fault current when the outgoing transmission line fails, the sensitivity of the pilot protection of wind farm outgoing transmission line decreases or even protection refuses to operate. Therefore, the pilot protection of wind farm outgoing transmission line based on edge detection is proposed. By constructing the current collected on both sides of the wind farm outgoing transmission line as a matrix, and using Sobel operator for edge detection, the part where the current sampling value changes greatly is determined. Then, the average gradient amplitude is calculated and compared with the set value by the identified part with large changes in the current sampling values on both sides of the line, so as to realize the rapid identification of internal faults and external faults. Finally, a large-scale wind farm outgoing transmission system model is built by PSCAD/EMTDC to verify the applicability, rapidity and ability against transition resistance of the proposed algorithm. Compared with the existing pilot protection of transmission lines, the proposed method is still applicable when the wind farm output is weak and the operation speed is faster.