变压器油纸绝缘系统多重硫腐蚀协同劣化作用机理与防护技术研究

Multiple active sulfides in the transformer oil could react with the copper conductor to form cuprous sulfide, which adheres to the surface of the copper wire and the insulating paper, reducing the oil-paper electrical properties and cause insulation failure. At present, most scholars mainly focused on the corrosiveness of the single sulfide DBDS, while few on other sulfides and their synergistic deterioration effects. Based on the macroscopic experiment and microscopic molecular simulation, the project intends to analyze the change rule of aging characteristic parameters under different sulfide, voltage and temperature, to clarify the reaction process and their mutual conversion of multiple sulfur corrosion. Also, the synergistic deterioration mechanism of the oil-paper insulation by different sulfurs would be revealed. By extracting the decoupling characteristic parameters which can quantitatively characterize the multiple sulfur corrosion degree, the mathematic correlation model of the sulfur compositions, the aging characteristic parameters and the sulfur corrosion severity can be established, also with the quantitative characterization method of the sulfur corrosion severity degree. The protection effectiveness of passivator under multiple sulfur corrosion would be studied and the optimal passivator concentration for different corrosive sulfurs will be proposed. This project has certain scientific significance and application value for further revealing the sulfur corrosion phenomenon and its synergistic degradation mechanism, as well providing theoretical basis and technical means for preventing the sulfur corrosion insulation fault.

变压器油中多种活性较强的硫化物与铜导线反应生成硫化亚铜，附着在铜导线和绝缘纸表面，降低油纸绝缘的电气性能而引发绝缘故障。目前国内外针对硫腐蚀现象的研究主要集中在单一硫化物DBDS，对其它硫化物及其协同作用下的绝缘劣化机理研究较少。本项目基于宏观实验研究和微观分子模拟，分析不同硫化物、电压、温度条件下油纸绝缘老化特征参量的变化规律，阐明多种腐蚀性硫化物的反应过程及其相互转化机制，揭示多重化硫腐蚀对油纸绝缘的协同劣化作用机理；提取可定量表征多重化硫腐蚀反应特性的解耦特征量，建立硫化物成分—老化特征参量—硫腐蚀严重程度的数学关联表征模型，提出多重化硫腐蚀严重程度的定量表征方法；研究多重硫腐蚀条件下钝化剂防护的有效性，提出针对不同类型硫腐蚀的钝化剂防护策略与最优添加浓度。本项目研究可深化理解多重化硫腐蚀现象及其协同劣化机制，为预防硫腐蚀绝缘故障提供理论依据与技术手段，具有重要的科学意义和应用价值。

变压器硫化物腐蚀问题已严重影响变压器的安全稳定运行，本项目针对多重硫腐蚀对油纸绝缘系统协同劣化作用机理的关键科学与基础性问题，开展理论探索与技术创新研究。将硫醚、硫醇、噻吩共同存在的环境纳入硫腐蚀研究体系，揭示了多重腐蚀性硫对油纸绝缘系统老化特性的影响规律。研究表明，硫化物浓度越高，其腐蚀性越强，对油纸绝缘老化的促进作用也越大；硫化物的加入会导致绝缘油中水分波动变大，酸值变大，介损增大，击穿电压下降；单一硫化物中，DBDS对铜片腐蚀性较强，硫醇对铜片腐蚀性相对较弱，噻吩一般不具有腐蚀性。当油中多种硫化同时存在时，对油纸绝缘系统老化的影响作用不等于各种硫化物单一存在时的线性叠加，添加相同浓度的两种硫化物时，DBDS与DBS的组合对油纸绝缘老化的促进作用最强。氧气对铜片表面腐蚀状况起抑制作用，这可能与高氧环境下硫化亚铜会从铜片表面脱落有关，但氧气对油纸绝缘系统中老化产物的产生起促进作用；温度会促进铜片的腐蚀，同时还会促进油纸绝缘系统中老化产物的产生；电压的存在会加速油硫腐蚀，造成油纸绝缘系统性能的降低。采用熵权法计算了不同硫化物影响的权重系数，提出了各硫化物随老化时间下降的公式，以定量表征硫腐蚀的严重程度。无论是对于已发生腐蚀的绝缘油还是已发生腐蚀的铜片，钝化剂都具有一定的防护有效性，可以阻止腐蚀的进一步发生，提出了针对不同腐蚀性硫种类和不同老化程度油样的钝化剂防护最优添加浓度。本项目研究深化揭示了多重化硫腐蚀现象及其协同劣化机制，可为预防硫腐蚀绝缘故障提供理论依据与技术手段。