基于紫外光谱检测的GIS内多类故障早期预警

摘要

气体绝缘开关（GIS）故障预警强调异常识别的实效性和现场适用性，是精确诊断的基础。研究GIS内局部放电（PD）及过热故障的统一预警方法具有重要意义。提出将SO2作为GIS内部两类故障公共的特征分解物，并应用紫外光谱（UV）测量SO2实现多故障早期预警。一阶导数法和Savitzky-Golay滤波被用于快速基线校正和光谱平滑，290～310 nm 被选为特征区进行 SO2检测及定量。UV 检测可避免诸如 SF6及SOF2、SO2 F2等分解物的干扰，便于从复杂的SF6分解物组分中识别微量SO2特征，测量系统结构简单、维护成本低、适于现场检测。通过模拟SF6气体在两类PD缺陷及200～400℃过热条件下的分解实验，证实所提UV预警方法的有效性：两类GIS故障条件下都会稳定的生成SO2。对UV预警后的故障诊断，借助傅里叶变换红外光谱仪及气相色谱仪，确认PD及过热故障下的分解物组分存在差异，并据此简要分析了故障类型辨识方法。PD分解物以SOF2和SO2 F2为主，SO2含量远小于SOF2，放电涉及环氧树脂时含碳分解物含量上升。过热材质为不锈钢时，SF6约在300℃发生分解，300～400℃内的过热分解物主要为 SO2和SOF2，350℃以上SO2生成速率明显快于PD时。随着GIS 内故障持续恶化，SO2含量均呈现稳定上升趋势。在UV预警后，可利用获得的SO2生成特性初步辨识故障类型。%As the basis of accurate diagnosis,fault early-warning of gas insulation switchgear (GIS)focuses on the time-effec-tiveness and the applicability.It would be significant to research the method of unified early-warning for partial discharge (PD) and overheated faults in GIS.In the present paper,SO2 is proposed as the common and typical by-product.The unified monito-ring could be achieved through ultraviolet spectroscopy (UV)detection of SO2 .The derivative method and Savitzky-Golay filte-ring are employed for baseline correction and smoothing.The wavelength range of 290~310 nm is selected for quantitative detec-tion of SO2 .Through UV method,the spectral interference of SF6 and other complex by-products,e.g.SOF2 and SOF2 ,can be avoided and the features of trace SO2 in GIS can be extracted.The detection system is featured by compacted structure,low ma-intenance and satisfactory suitability in filed surveillance.By conducting SF6 decomposition experiments,including two types of PD faults and the overheated faults between 200~400 ℃,the feasibility of proposed UV method has been verified.Fourier transform infrared spectroscopy and gas chromatography methods can be used for subsequent fault diagnosis.The different de-composition features in two kinds of faults are confirmed and the diagnosis strategy has been briefly analyzed.The main by-prod-ucts under PD are SOF2 and SO2 F2 .The generated SO2 is significantly less than SOF2 .More carbonous by-products will be gen-erated when PD involves epoxy.By contrast,when the material of heater is stainless steel,SF6 decomposes at about 300 ℃ and the main by-products in overheated faults are SO2 and SO2 F2 .When heated over 350 ℃,SO2 is generated much faster.SO2 con-tent stably increases when the GIS fault lasts.The faults types could be preliminarily identified based on the generation features of SO2 .