基于紫外光谱检测的GIS内多类故障早期预警

Early Warning for Various Internal Faults of GIS Based on Ultraviolet Spectroscopy

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,290~310nm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、SO2F2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SO2F2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 SFs and other complex by-products, e.g. SOFz and SOFz, 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 SF~ 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 arc 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 SO2F2. When heated over 350 ℃, SOs 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.