特高压换流变阀侧油浸表带触指腐蚀特征与快速检测

Corrosion Analysis and Rapid Detection of Contact Strips in Valve-side Ascending Flange of UHV Converter Transformer

摘要:

特高压换流变压器阀侧油中表带触指作为实现绕组引出线与阀侧套管电气连接的关键部件，长期服役在高电压、大电流、高环温等严苛条件下，难以避免出现腐蚀、劣化等情况。以在役表带触指劣化故障实例为基础，通过扫描电子显微镜、能量色散光谱仪、X射线衍射仪等检测手段探究了表带触指表面腐蚀产物的微观形貌演变，分析了腐蚀层主要成分及含量，后经由显微切片与表面磨抛观测探究了其腐蚀产物的分布特征。研究结果表明：腐蚀产物大多数仅附着于表带触指表面，未向内侵蚀，推断腐蚀产物Cu2S主要由油中Cu离子与腐蚀性硫化物结合沉积而来。最后，提出了一种基于机器学习结合激光诱导光谱信号的快速检测分析方法，实现了对触指4类不同腐蚀程度的有效识别，准确度可达到99.25%。

Abstract:

The strap contacts in the oil of valve side of UHV converter transformer serves as a key component to achieve the electrical connection between the winding lead out line and the valve side bushing. Operating under harsh conditions such as high voltage, large current, and high ambient temperatures in long term service, it is difficult to avoid issues such as corrosion and degradation. Based on a case of degradation failure of strap contacts in the oil of valve side of an in service UHVDC converter transformer, the microscopic morphological evolution and the main components and content of corrosion products on the surface of strap contacts are investigated using scanning electron microscopy, energy dispersive X-ray spectroscopy, X-ray diffraction, and other detection methods. At the same time, the distribution characteristics of corrosion products are investigated through the cross section and surface polishing. The research results show that the majority of corrosion products adheres only to the surface of strap contacts,and it is inferred that the corrosion product Cu2S is mainly deposited by the combination of Cu ions and corrosive sulfides in the oil. Finally, a rapid detection and analysis method based on machine learning algorithms combined with laser induced spectroscopic signals is proposed, which achieves an effective identification of four different levels of corrosion on strap contacts, with an accuracy up to 99.25%.