温度对复合电压下油纸绝缘电场分布的影响

Influence of Temperature on Electric Field Distribution of Oil-paper Insulation Under Compound Voltage

为研究温度对复合电压下油纸绝缘电场分布的影响规律,该文在实验室中开展温度及含水率对油纸绝缘的电阻率及相对介电常数影响的试验研究,在此基础上通过仿真手段分析复合电压下油纸绝缘电场分布与温度的关系特性。试验结果表明,温度对油和浸油纸板的相对介电常数影响较小,但对电阻率的影响较大;随温度的升高油和浸油纸板的电阻率都呈指数规律下降,但两者的下降速度存在较大的差异;浸油纸板和油的电阻率随含水率增加均按指数规律下降。仿真结果表明,温度升高将导致纸中电场强度下降和油中电场强度上升,且水分平衡处于暂态过程时油纸绝缘中电场强度的变化幅值比稳态时的变化幅值大得多,交流含量越低该现象越明显。分析后得出结论,油和纸相对介电常数的比值随温度变化较小,而两者电阻率的比值随温度变化大,这是导致低交流含量的复合电压下温度对油纸绝缘电场分布有较大影响的主要原因。

In order to study the temperature influence on the electric field distribution of oil-paper insulation under compound voltage, the experiment research was carried out to study the influences of temperature and moisture on the relative dielectric constant and resistivity of oil-paper insulation. Then, the characteristics of electric field distribution with temperatures were analyzed under compound voltage by simulation method. The experiment result shows that, temperature has little influence on the relative dielectric constants of oil and pressboard, but has huge influence on their resistivity. As temperature rises, the resistivity of oil and pressboard both falls exponentially, but there are great differences between their decent rates. The resistivity of oil and pressboard both decrease exponentially, as well as, with the moisture growth. The simulation results show that electric strength decreases in paper, but increases in oil, as the temperature rises. During the transient process of moisture equilibrium, the variation amplitude of electric strength in pressboard and oil is much larger than that under the stable condition, and this phenomenon shows more obvious characteristics under the lower AC content voltage. By analyzing, the conclusion can be drawn that the relative dielectric constant ratio of paper and oil varies slightly with temperature, but the resistivity ratio varies seriously, which is the main reason that results in the electric field distribution affected by temperature seriously under low AC content compound voltage.