摘要
油纸绝缘作为变压器的主要绝缘部分,长期运行后变压器主绝缘发生的非均匀老化现象,在复杂运行条件下(环境温度、受潮情况,电压类型)将导致工况运行时主绝缘内的电场分布发生变化,因此明确工况运行下非均匀老化油纸绝缘内特征位点(最大场强处)电场的变化特性至关重要。通过开展不同老化、受潮程度油纸绝缘材料的介电参数测试,明确了老化后油纸绝缘材料的工频介电常数、直流电导率随着运行条件的变化规律,通过构建基于GA-BP神经网络的老化油纸绝缘材料介电参数模型,实现了非均匀老化油纸绝缘介电参数的多元非线性定量表征;同时考虑油浸纸板老化对油纸间水分平衡规律存在的影响,修正了非均匀老化油纸绝缘内的油纸水分分布,并根据典型非均匀老化主绝缘结构,构建了非均匀老化油纸绝缘典型电场分布模型;最后,考虑到当前特高压电网中,区别于普通交流变压器绝缘所承担的交流电压,换流变压器阀侧绕组承担的电压中含有较高的直流分量,导致其面对的更高的绝缘水平要求。通过分别设定两种外施电压,并在复杂运行条件下,针对不同非均匀老化阶段的油纸绝缘模型的典型电场分布进行仿真计算,揭示了非均匀老化油纸绝缘电场变化特性,明确了实际运行中应加以注意的运行工况,为变压器的运维策略提供了重要的理论支撑。
As the main insulation component of transformers,oil-paper insulation experiences non-uniform aging phenomena after a long-term operation,which can cause changes in the electric field distribution inside the main insulation under complex operating conditions(ambient temperature,moisture conditions,and voltage type).Therefore,it is crucial to identify the variation characteristics of the electric field changes at the feature location(where the maximum field intensity occurs)inside the non-uniformly aged oil-paper insulation under operating conditions.This paper conducts dielectric parameter tests on oil-paper insulation materials subjected to different aging and moisture levels.It elucidates the variations in the frequency-dependent dielectric constant and DC conductivity of aged oil-paper insulation materials under different operating conditions.A comprehensive multi-dimensional nonlinear quantitative representation of non-uniformly aged oil-paper insulation is achieved by constructing a GA-BP neural network-based model for the dielectric parameters of aged oil-paper insulation.Additionally,considering the influence of aging on the water content equilibrium in oil-impregnated paper,the distribution of moisture within non-uniformly aged oil-paper insulation is corrected.Furthermore,based on typical non-uniformly aged main insulation structures,a model for the typical electric field distribution of non-uniformly aged oil-paper insulation is established.Finally,considering the distinct operating conditions in ultra-high voltage power grids,where valve-side windings in converter transformers experience higher DC voltage components in addition to AC voltage,imposing higher insulation requirements.This paper sets two different external voltages and conducts simulation calculations on the typical electric field distribution of oil-paper insulation models at different stages of non-uniform aging under complex operating conditions.It reveals the variation characteristics of the electric field in non-uniformly aged oil-paper insulation,identifies critical operating conditions to be considered during actual operation,and provides important theoretical support for transformer operation and maintenance strategies.
作者
梁一霖
张明泽
刘骥
雷胜杰
贾海峰
李璐
LIANG Yilin;ZHANG Mingze;LIU Ji;LEI Shengjie;JIA Haifeng;LI Lu(Key Laboratory of Engineering Dielectrics and Its Application Ministry of Education,Harbin University of Science and Technology,Harbin 150080,China;Electric Power Research Institute,State Grid Heilongjiang Electric Power Company Limited,Harbin 150030,China)
出处
《高电压技术》
EI
CAS
CSCD
北大核心
2024年第4期1731-1741,共11页
High Voltage Engineering
基金
国家自然科学基金(52307164)
黑龙江省博士后基金(LBH-Z22202)。
关键词
油纸绝缘
非均匀老化
非线性介电性能
电场变化特性
交直流复合电场
oil-paper insulation
non-uniform aging
nonlinear dielectric properties
variation characteristics of electric field
AC/DC composite electric field
