【作者】 陈攀；

【导师】 姚陈果；

【作者基本信息】 重庆大学 ， 电气工程， 2014， 博士

【摘要】 对高压开关柜内电气元件的局部放电（Partial Discharge, PD）开展在线监测与识别能够有效评估和判断其复杂的内绝缘的运行状态，能够在故障发生前采取及时有效的解决措施，从而有效保障其安全运行。传统的超高频（Ultra High Frequency,UHF）检测法需要获取完整的信号波形，通过分析信号波形特征实现放电的诊断，对硬件系统的采样率、传输带宽和信号处理速度提出了苛刻要求，故需在检测手段和诊断理论上进行突破和创新，而局部放电超高频信号的能量特征能有效用于放电故障的分析和诊断。因此，研制一种获取超高频局部放电信号的新型超宽带、超高频天线传感器，采用该天线传感器结合分频段信号能量提取的前置信号处理电路及其在线监测系统，降低系统对采样率、传输带宽和信号处理速度的需求，并利用聚类算法构建基于能量特征的局部放电故障模式识别新方法，对于局部放电的监测和诊断有着重要的理论意义和广阔的应用前景。为此，本文在传统超高频检测法的基础上，分析开关柜内电磁波传播特性，深入研究局部放电超高频信号能量特征提取及故障模式识别的新方法，取得的主要成果有：①根据高压开关柜的结构尺寸及材料参数建立了精确计算模型，分别仿真柜内电流互感器等四种主要部件对电磁波传播特性的影响，得出其影响规律；综合分析六种放电情况下各检测点信号检测的波动性、各种放电的总体检测性能及绝缘距离等因素，确定了天线传感器的最佳检测点，并通过实验平台的搭建和实测验证了该检测点的效果最佳。②以传统微带天线为基础，设计出宽带分形天线。在此基础之上，结合分形扩频理论，通过对天线性能参数的计算分析及优化仿真，结构尺寸的优化调整，全面提升了天线的信号接收性能，研制出了一种新型超宽带、超高频分形天线传感器。该天线传感器结构尺寸小，安装方便，接收频带为0.4-1GHz，平均增益约为1.7dB，可接收全方位的电磁信号。在超高频天线传感器接收性能方面取得了整体提升，实现了突破和创新。③首次引入混频理论和功率包络检波技术等射频电路理论，设计了提取局部放电超高频信号能量的前置信号处理电路及其在线监测系统。通过对自噪水平、带外抑噪能力、输入-输出响应特性及增益-频率特性的测试，表明该电路稳定可靠，能够有效实现信号的分频输出和能量提取，实现对超高频信号处理方式的创新。④设置了4种典型绝缘缺陷的故障模拟平台，分别模拟不同局部放电类型。针对各个典型绝缘故障下不同试验电压的试验结果和不同绝缘故障的试验结果，提取三个分频段的能量占全频段能量的百分比，作为模式识别的指纹特征量。通过构建指纹图谱，证实了局部放电超高频信号的能量特征具有类聚特性。首次利用马氏距离聚类算法和分频理论构建了基于信号能量特征的局部放电模式识别判据，并通过回判算法验证了该识别判据的误判率仅为0.875%。综上所述，研制的新型超宽带、超高频分形天线传感器性能优异，结合射频电路理论研制的信号能量特征提取电路能够有效降低对系统采样率、传输带宽和处理速度的要求，而基于信号能量特征的局部放电故障模式识别方法是监测局部放电故障的最新研究热点和理论突破口，在局部放电监测领域具有广阔的学术研究空间和良好的应用前景。更多还原

【Abstract】 On-line monitoring and recognition of partial discharge (PD) occurred in HVswitchgear is an effective way to evaluate internal insulation condition and status. It canhelp to make pre-fault decisions in a timely manner to ensure the switchgear’s safety.Traditional ultra high frequency (UHF) detection acquires complete waveform of PDsignal and diagnoses discharge types by analyzing the features of PD signal, thus it setsdemanding requirements on sampling rate, transmission bandwidth and signalprocessing speed of the detection system. Novel detection method and diagnose theoryneeds to be refined and proposed. Since energy features of UHF PD signal is capablefor fault analysis and diagnosis, designing one kind of UHF antenna with largebandwidth to collect UHF PD signal, developing on-line monitoring system with signalpre-processing circuit by extracting sub-band signal energy to lower the demandingrequirements of traditional UHF method, and proposing an pattern recognition methodfor PD fault analysis using cluster algorithm, is of theoretic significant and applicationvalue for PD on-line monitoring and recognition.Based on the traditional UHF detection, this thesis analyzes the transmissioncharacteristics of electromagnetic wave occurred in switchgear, proposes an novelpattern recognition method for PD fault analysis by extracting features of PD UHFsignal energy. The whole thesis is summarized as:①Depending on size and material parameters, a real model of HV switchgear isestablished. Impact of four major components in the switchgear on electromagneticwave propagation characteristics is analyzed and summed up. Considering issues suchas overall detection performance, volatility of test result of six different PD sources andsafe distance, optimal installation location of antenna sensor is determined bycomprehensive comparison of detection performance under different locations. Thispoint is validated to be of the best performance by measured results obtained from thetesting platform.②Based on traditional microstrip antenna, a fractal antenna with large bandwidthis designed. Combined with the spread fractal theory, a novel UHF fractal antennasensor is developed by analysis and simulation and adjustment of the antenna structuresize. The sensor promotes the signal receiving performance largely with the receiving0.4-1GHz and average gain1.7dB. Full range of electromagnetic signals can be received. Moreover, it has compact size and can be easily installed. The receptivity ofnew UHF fractal antenna achieves the overall ascension, which is a kind of sciencebreakthrough.③For the first time, based on mixing theory and power envelope detectiontechnique, on-line monitoring system for UHF PD signal with signal pre-processingcircuit by extracting sub-band signal energy is developed. White noise level,out-of-band noise suppression, I/O response characteristics, and gain-frequencycharacteristics are tested and results show that the circuit is stable and reliable, and canrealize sub-frequency output and energy extraction, which is a new signal dealing wayfor UHF signal.④Four kinds of typical insulation defects are set in real test platform to simulatedifferent PD type. Aiming at various testing results under different testing voltage anddifferent insulation, the proportions of three sub-band energy to whole band energy arecalculated as features for PD pattern recognition. By establishing a fingerprint database,the energy features of UHF signals with cluster characteristics is validated. For the firsttime, Mahalanobis distance with frequency divide theory is introduced as criterion forenergy based PD pattern recognition. Back sentenced algorithm shows that themisjudgment rate was0.875%.In summary, the developed UHF fractal antenna sensor with large bandwidth hasexcellent performance, and the signal energy extraction circuit can effectively lower thedemanding requirements on sampling rate, transmission bandwidth and signalprocessing speed of the traditional UHF detection system. Energy feature based PDpattern recognition has become the latest hot spot and theoretical breakthrough of PDmonitoring, which will have broad academic value and application prospect.更多还原