基于介电响应技术的变压器油纸绝缘含水率数值评估方法

Numerical Evaluation Method for Moisture Content of Transformer Oil-Paper Insulation Based on Dielectric Response Technique

变压器绝缘纸板中的含水率是评估变压器内部绝缘老化的重要指标,为了运用介电响应技术测量变压器绝缘纸板含水率,首先对变压器XY等效模型及复合介质介电常数算法进行理论推导,得到绝缘纸板中含水率与XY等效模型介质损耗因数之间的关系,同时结合实验测试数据与频温叠加的基本思想,得出关于纯新油浸纸板复介电常数实部、虚部的具体表达式,将其代入绝缘纸板含水率与损耗因数的关系式中,得到迭代拟合算法。为进一步验证上述含水率拟合算法有效性,现阶段本文在实验室条件下制备了三种不同比例的XY等效模型,在不同温度条件下进行模型损耗因数测试,应用IDAX-300绝缘纸板含水率测试软件与本文迭代算法对测试结果分别进行拟合计算,发现试验中本文迭代拟合算法计算含水率平均误差为4.83%。

The moisture content in the pressboard is an important index to evaluate the aging performance of transformer insulation.In order to apply dielectric response technique to measure the moisture content of transformer pressboard,this paper deduces the equivalent model of transformer XY and the algorithm of dielectric constant of mixed dielectric.The relationship between the moisture content in pressboard and dielectric loss of XY equivalent model is obtained.At the same time,combining the experimental data and the basic idea of time-temperature superposition,the specific formulas of the real and imaginary parts of the complex dielectric constant of dehydrated pure new oil impregnated pressboard are obtained.Then the obtained formulas are introduced into the relational equation of the moisture content and dielectric loss of pressboard.A cyclic iterative fitting algorithm is obtained.XY equivalent models of three different proportions are prepared under laboratory conditions for the test of dielectric loss under different temperature conditions.Compared with the test results by the insulation pressboard moisture content test software of IDAX-300 equipment,it is found that the mean error of the moisture content calculated by the proposed iterative algorithm is 4.83%.