The XY model is a simplified insulation model for transformers that aims to connect the frequency spectrum of major insulation, insulation paper, and oil. It enables the calculation of the paper's frequency spectrum, facilitating a quantitative evaluation of the transformer's insulation status. Given the scarcity of research addressing the accuracy of the XY model and its corresponding equivalent circuit, this paper investigates the accuracy of the XY model and conducts an in-depth analysis of the error associated with its equivalent circuit. Firstly, the frequency spectrum of oil-paper insulations based on the XY model with varying moisture content and structure configurations were measured, followed by the simulation of both the corresponding 2D-coaxial and XY models. By comparing the results obtained from these simulations with experimental data on oil-paper insulation, the accuracy of XY model is verified. Subsequently, two variants of the equivalent circuit of the XY model are derived by combining the oil, spacer, and paper differently, which denoted as Type I and II circuits. Finally, we analyzed and explained the errors present in these equivalent circuits compared with the XY model. Our findings show that the width-thickness ratio of oil-paper insulation is the most critical influencing factor, while moisture content and insulation structure have a less decisive impact. Notably, for general transformers, as the width-thickness ratio is between 30 and 70, the relative error of the Type I circuit remains consistently below 0.3% across different frequencies. Consequently, the Type I circuit proves to be a more suitable representation of the equivalent circuit for the XY model in the context of general transformers. © 2024 Institute of Electrical Engineers of Japan. Published by Wiley Periodicals LLC.

中文翻译：

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基于有限元仿真的XY模型等效电路误差分析

XY模型是变压器的简化绝缘模型，旨在连接主要绝缘、绝缘纸和油的频谱。它可以计算纸张的频谱，有利于定量评估变压器的绝缘状态。鉴于目前关于XY模型及其等效电路精度的研究较少，本文研究了XY模型的精度，并对与其等效电路相关的误差进行了深入分析。首先，测量了基于 XY 模型的不同含水量和结构配置的油纸绝缘的频谱，然后对相应的 2D 同轴模型和 XY 模型进行了仿真。通过将模拟结果与油纸绝缘实验数据进行比较，验证了XY模型的准确性。随后，通过油、垫片和纸的不同组合，得到了XY模型等效电路的两种变体，分别表示为I型和II型电路。最后，我们与 XY 模型相比，分析并解释了这些等效电路中存在的误差。我们的研究结果表明，油纸绝缘的宽厚比是最关键的影响因素，而含水量和绝缘结构的决定性影响较小。值得注意的是，对于一般变压器，由于宽厚比在30至70之间，I型电路的相对误差在不同频率下始终保持在0.3%以下。因此，I 型电路被证明是通用变压器背景下 XY 模型等效电路的更合适表示。 © 2024 日本电气工程师协会。由 Wiley 期刊有限责任公司出版。