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摘要:
热斑现象是造成光伏组件发电能力下降的重要原因之一,热斑检测是光伏电站运维必不可少的工作。然而分布式光伏电站的规模普遍较小、选址分散、环境复杂多样,使用传统的热斑检测算法需要投入大量的人力资源。基于此,提出了一种基于注意力机制的热斑检测算法HSNet。通过图像分割消除反光影响,结合通道注意力机制,学习通道间的特征信息,增强目标区域的重要性,采用自定义锚点的方法提高检测速度,使用焦点损失激活函数和基于物体先验概率的类别预测方式改善训练目标样本不均衡导致的分类准确性低的问题,通过回归方法获取准确的目标位置。实验表明:设计的目标检测算法在窗体回归精度和分类准确性方面均有明显的优势,边界框平均精度和准确率分别提升了3.18%和2.42%。
Abstract:The hot spot phenomenon is one of the important reasons for the reduction of power generation capacity of photovoltaic panels, and the detection of hot spots is an essential task for operation and maintenance personnel. The scale of distributed photovoltaic power plants is generally small, the site is scattered, the environment is complex and diverse, and the operation and maintenance personnel need to invest a lot of human resources to detect hot spots using traditional hot spot detection methods. In this paper, we propose a new hot spot detection algorithm HSNet. Firstly, the influence of reflection is eliminated through image segmentation. Secondly, the feature information between channels is learned in combination with the channel attention mechanism to enhance the importance of the target area. The method of user-defined anchor points is used to improve the detection speed. Then, the focus loss activation function and the category prediction method based on the prior probability of objects are used to improve the problem of low classification accuracy caused by the imbalance of training target samples, Finally, the accurate target position is obtained by regression method. Experiments show that the target detection algorithm designed in this paper has significant advantages over other algorithms in terms of window regression accuracy and classification accuracy, and the mean accuracy and accuracy of the bounding box are improved by 3.18% and 2.42%, respectively.
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表 1 符号表示
Table 1. Symbolic representation
符号 含义 D 训练集 Ii 第i张图像 yij 第i张图像的第j个光伏组件的类别 x 层运算输入 F 卷积等层计算公式 Lcls 分类损失函数 PL(pt) 概率为pt的Focal Loss损失函数 bboxcls 回归损失函数 SE SE处理模块 GT Ground Truth人工标注框 M 训练模型 ReLU ReLU激活函数 θF 初始化网络模型参数 batch_size 训练图像批量大小 FM 提取的特征图 (Ox, Oy), Ow, Oh 输出目标的位置及目标的宽度和高度 表 2 不同标注框的数量
Table 2. Number of different kinds of labeled boxes
种类 图像数量 标注框数量 占比/% normal 440 24 846 89.32 dirty 286 2 736 9.84 hotspot 28 109 0.39 hotline 98 125 0.45 表 3 不同模型的结果对比
Table 3. Comparison of results with different models
算法 bbox_mAP/% mAP/% 准确率/% HSNet 55.97 70. 95 98.22 Faster R-CNN 50.64 67.77 95.80 RetinaNet 20.98 38.17 43.92 SSD300 66.57 67.96 96.50 YOLOv3 48.78 59.48 91.32 表 4 消融实验结果
Table 4. Results of ablation experiments
算法 bbox_mAP/% mAP/% 准确率/% F-RCNN 50.64 67.77 95.80 F-RCNN+UN 51.72 68.86 96.92 F-RCNN+UN+RN 53.68 68.92 96.99 F-RCNN+UN+SE 55.38 69.18 96.43 F-RCNN+UN+FL 52.21 69.30 96.95 F-RCNN+UN+RN+FL 54.23 69.58 97.34 F-RCNN+UN+SE+FL 55.85 70.50 98.01 F-RCNN+UN+SE+FL+PRI 55.97 70.95 98.22 -
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