变压器油纸绝缘老化含水率频域法定量评估

Quantitative Assessment of Moisture Content in Frequency Domain Response For Transformers Oil-Paper Insulation Aging

变压器由于老化和受潮等因素使得内部油浸纸板含水率大大升高,文中以变压器等效模型及复合介质介电响应模型为基础,同时结合实验室数据与频温叠加等基本理论,得到了一种变压器内部油浸纸板中含水率的定量计算方法。为验证算法的有效性,设计了常温下测试自然吸潮及加速热老化后等效模型的含水率分析性试验,从试验结果发现,对于自然吸潮模型,应用本文算法计算含水率的结果更接近于滴定值,拟合曲线的优度决定计算结果的准确性;对于老化后的模型, IDAX-300 拟合算法在较宽频率段测试老化后模型含水率时计算结果偏高;通过不同老化条件下油纸绝缘模型与变压器缩比模型进行试验验证,可得应用文中的算法,灵活选取计算频域范围,解决了老化后低分子产物对测试计算结果影响偏大这一问题,含水率的计算结果更接近于真实滴定值。

Due to aging and moisture, the moisture content of transformer's oil-immersed pressboard is greatly increased. Based on the equivalent model of transformer and the dielectric response model of composite medium, meanwhile, based on laboratory data and frequency temperature superposition theory, a quantitative calculation method of moisture content in oil-immersed pressboard of transformer is obtained. In order to verify the validity of the algorithm,the moisture content of equivalent model after natural moisture absorption under variable temperature and the moisture content of equivalent model after aging test at room temperature are experimentally analyzed. The test results reveal that, for the XY model of natural moisture absorption, the results calculated by this algorithm are closer to the titration values. The accuracy of cal- culation results is determined by the goodness of fitting curve. For the model of aging, the result of IDAX-300 fitting algorithm is relatively high when the moisture content of the model is tested after aging at a wide frequency range. Moreover, the oil-paper insulation model and transformer scaling model under different aging conditions are tested and verified. Using the numerical iterative algorithm, we flexibly choose the computation frequency domain to solve the problem that the low molecular material product after aging will remarkably affect the test results. The numerical iterative fitting results of moisture content are closer to the real titration value.