In order to improve the recognition effect of tree line grounding fault detection in power system, an improved YOLOv8 model is proposed. The model enhances the feature representation ability by inserting the SimAM attention mechanism, and uses the GIoU loss function to improve the accuracy of the bounding box prediction and improve the fault recognition performance of the model in complex environments. In order to verify the performance of the improved YOLOv8 model, the ablation experiment, the insertion position change experiment of the SimAM attention mechanism module, the loss function selection experiment, and the comparison experiment with other recognition models are carried out. The experimental results show that the improved YOLOv8 model has the highest recognition accuracy, recall rate and average accuracy. The model effectively improves the recognition accuracy of the tree-line grounding fault detection image and provides support for the intelligent operation and maintenance of transmission lines.
YOLOv8原始模型采用CIoU (complete intersection over union)损失函数[17-18],该函数在处理不同形状目标的相关性时,未考虑样本难易程度的区分问题。GIoU(generalized intersection over union)损失函数在保留IoU的尺度不变性的同时,进一步考虑了目标的非重叠区域,可以更准确描述不同形状目标之间的关系。此外,GIoU损失函数可以反映目标的难易程度,弥补CIoU损失函数在相关性描述和样本区分上的不足。因此,本文采用GIoU损失函数替换CIoU损失函数。
采用不同的损失函数,对改进YOLOV8模型进行实验,结果见表3。由表3可知,DIoU(distance intersection over union)损失函数通过最小化预测框和真实框中心点距离,加快模型的收敛速度,但未能有效处理长宽比的差异,因此其mAP_0.5:0.95值略小于GIoU损失函数。CIoU损失函数在DIoU损失函数的基础上进一步引入长宽比一致性作为惩罚项,提升了回归精度,但仍未能在非重叠情况下提供足够的优化信息,限制了其性能的进一步提升。EIoU(efficient intersection over union)损失函数和SIoU(scaled intersection over union)损失函数均细化了长宽比和方向惩罚项,但对于树线接地故障的特征复杂性较高的特定任务,没有使模型的mAP值提高。Shape IoU(shape intersection over union)损失函数强调预测框与真实框形状的相似性,但在目标边界复杂的场景下,其形状优化的作用相对有限。
LUOChen, FENGYu, WUKai, et al. A lightweight outage perception model for power grids based on prompt learning from multi-source outage data [J/OL].Modern Electric Power,1-11.(2023-12-18) [2024-05-14].
ZHANGMeijin, KUAIYu, CAIZhijun,et al.Multi-criteria fusion fault line selection for improved zero-sequence current component[J]. Journal of Liaoning Technical University (Natural Science),2020,39 (1):71-77.
NINGXin, HUXinyue, ZHANGHua,et al.Characteristic analysis of tree-contact single-phase-to-ground fault in power distribution lines [J]. Proceedings of the CSU-EPSA,2023,35(7):137-143.
ZHAOShenyuan, CHENTianxiang, XUHuikai,et al Experimental research on transient impedance variation characteristics of 10 kV tree line faulted trees[J].Journal of Guangxi University (Natural Science Edition), 2023,48(2):393-406.
YANGSenlin, YANGChangqing, MEIJiming,et al.Research and application status on forest fire risk assessment and monitoring for overhead transmission lines[J].Journal of Sichuan Forestry Science and Technology,2021,42(6):126-130.
LAIQiupin, YANGJun, TANBendong,et al.An automatic recognition and defect diagnosis model of transmission line insulator based on YOLOv2 network[J].Electric Power,2019,52(7):31-39.
HAOShuai, MARuize, ZHAOXinsheng, et al.Fault detection of YOLOv3 transmission line based on convolutional block attention model[J].Power System Technology,2021,45(8):2979-2987.
ZHENGWei, YANGXiaohui, ZhongbinLYU,et al.Real-time inspection model for key components of transmission lines based on improved YOLOv4[J].Science Technology and Engineering,2021,21 (24):10393-10400.
HAOShuai, YANGLei, MAXu,et al.YOLOv5 transmission line fault detection based on attention mechanism and cross-scale feature fusion[J].Proceedings of the CSEE,2023,43(6):2319-2331.
ZHOUFei, GUODudu, WANGYang,et al.Vehicle detection algorithm based on improved YOLOv8 in traffic surveillance[J].Computer Engineering and Applications,2024,60(6):110-120.
[25]
YUZ F.Sim-YOLO:a real-time Chinese scene text detection method[C]//2023 IEEE 7th Information Technology and Mechatronics Engineering Conference.September 15-17,2023,Chongqing,China. IEEE,2023:2305-2309.
BAOCongwang, ZHUGuangyong, ZOUWang,et al.Rearing fault transfer diagnosis model based on SimAM attention mechanism[J]. Journal of Mechanical & Electrical Engineering,2024,41(5):862-869, 893.
TIANTian, CHENGZhiyou, JUWei,et al.Small sample classification of tea diseases based on SimAM-ConvNeXt-FL[J].Transactions of the Chinese Society for Agricultural Machinery,2024,55(3):275-281.
LIUXiangju, LIUYang, JIANGShexiang. DCN-YOLOv5 underwater target detection based on SimAM attention[J/OL].Journal of Chongqing Technology and Business University (Natural Science Edition),1-9.(2023-10-23)[2024-12-19].
WANGHaiyong, WANGZhiqing.Improved SSD object detection algorithm based on attention and feature fusion[J].Software,2023,44 (4):1-5.
[38]
REZATOFIGHIH, TSOIN, GWAKJ,et al. Generalized intersection over union: a metric and a loss for bounding box regression[C]//2019 IEEE/CVF Conference on Computer Vision and Pattern Recognition. June 15-20,2019,Long Beach,CA,USA.IEEE,2019:658-666.