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基于分布反馈光纤激光器的局部放电检测研究

Research on partial discharge detection based on a distributed feedback fiber laser

  • 摘要: 为了预防电力设备绝缘故障产生局部放电造成电力安全问题,搭建典型局部放电模型和复杂局部放电模型,并对每个模型加载不同强度的工频电压使其产生放电,利用分布反馈光纤激光器(DFB-FL)采集模型放电时产生的振动信号,通过振动检测系统对局部放电引起的振动信号进行了处理分析,采用长短期记忆支持向量机复合分类器(LSC-Classifier)算法对局部放电进行了模式识别。结果表明,典型放电模型识别准确率相较于支持向量机和长短期记忆网络分别提高了7%和2%,复杂放电模型识别准确率分别提高了18%和10%。此研究结果验证了使用DFB-FL对各类局部放电检测的有效性和LSC-Classifier算法对局放模式识别的准确性。

     

    Abstract: Partial discharge is an early indicator of insulation failure in power equipment. Accurate detection and pattern recognition are crucial for preventing safety issues caused by insulation failure. Partial discharge generates vibration signals, which can be leveraged for sensing. Owing to the advantages of the distributed feedback fiber laser (DFB-FL), including its high sensitivity, small size, easy integration, and anti-electromagnetic interference, it was employed as a sensing element to detect vibration signals caused by partial discharge. Different types of partial discharge models were constructed. Vibration signals generated by partial discharge were collected using DFB-FL, and the characteristics of these vibration signals were analyzed. The LSC-Classifier algorithm was utilized to adaptively learn vibration signal features under different models for partial discharge pattern recognition. Based on partial discharge theory, three discharge models were established—air-gap, creepage, and sharp-plate—using a power frequency voltage signal as the excitation source. In the air-gap model, the discharge position was aligned with the positive and negative half cycles of the voltage signal, and the partial discharge vibration duration and intensity in both half cycles were similar. For the creepage model, the discharge position also corresponded to the positive and negative half cycles of the voltage signal. The partial discharge vibration generated in the positive half cycle had a shorter duration and stronger vibration intensity, while that in the negative half cycle exhibited a longer duration and weaker vibration intensity. In the sharp-plate model, the discharge position was associated with the negative half cycle of the voltage signal, resulting in a longer duration and weaker vibration intensity of the partial discharge vibration. As the excitation voltage continued to rise, discharge phenomena were also induced in the positive half cycle. Three discharge models, namely suspension, metal particle, and metal strip models, were established based on the practical application scenarios of partial discharge. In the suspension model, when the excitation voltage was elevated, a longer vibration time was observed, while the vibration intensity remained unchanged. For the metal particle model, although the vibration duration showed no alteration with the rising excitation voltage, the vibration intensity increased. In the metal strip model, both the vibration duration and intensity increased as the excitation voltage rose. The incorporation of these composite discharge models provided more comprehensive and realistic discharge data for partial discharge pattern recognition. To evaluate the predictive performance of the support vector machine (SVM) and the long short term memory (LSTM) models, comparisons were conducted based on metrics such as accuracy, precision, recall, and F1 score. It was found that the LSTM model outperformed the SVM model across all indicators; however, its accuracy in recognizing complex partial discharge patterns was insufficient for precise type determination. By integrating the advantages of SVM and LSTM models, an LSC-Classifier fusion algorithm was proposed for pattern recognition. This algorithm enhanced the overall recognition accuracy of the typical discharge model by about 7% and 2%, respectively, compared to SVM and LSTM models. Moreover, the overall recognition accuracy for the composite discharge model was improved by approximately 18% and 10% compared to the SVM and LSTM models, respectively. Experimental results validated that the application of neural network learning algorithms, when applied to the pattern recognition of partial discharge signals based on DFB-FL vibration sensing systems, exhibited superior feasibility and accuracy, thereby demonstrating strong potential for practical partial discharge detection.Current partial discharge detection is predominantly conducted under controlled laboratory conditions, which represent idealized environments. However, empirical observations reveal that temperature and humidity variations significantly influence partial discharge signal detection reliability, occasionally resulting in undetectable signals. These environmental factors should therefore be systematically taken into account in future research to enhance practical applicability.

     

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