Abstract

The frequency domain spectroscopy (FDS) technique is widely used for the aging condition assessment of cellulose insulation on the bushing core. Generally, these assessment activities could be completed by the analysis of the FDS data between the laboratory sample and field bushing with the help of the traditional X-model. However, the aging condition of cellulose insulation on the bushing core is non-uniform due to the existence of temperature gradient. In this case, the traditional X-model is considered inappropriate since it ignored the effect of non-uniform thermal aging. In view of this issue, a modified X-model is reported in this work. Relying on the theoretical analysis of the modified X-model, both the mathematical expression and the equivalent circuit is derived naturally. The reliability of the modified X-model is confirmed by the experimental researches. In addition, the effect of aluminum foil in the modified X-model on FDS data was also studied. Findings reveal that the addition of aluminum foil would cause a slight deviation of the FDS curves. Therefore, the modified X-model might utilize to study the information of the non-uniform thermal aging. In that respect, the contribution of this work is in the exploration of the modified X-model as a potential tool for connecting FDS data corresponding to the lab condition and field condition including non-uniform thermal aging of cellulose insulation on the bushing core.

Graphic abstract

摘要

频域光谱（FDS）技术被广泛用于评估套管芯上纤维素绝缘的老化条件。通常，借助传统的X模型，可以通过分析实验室样品和现场套管之间的FDS数据来完成这些评估活动。但是，由于温度梯度的存在，套管芯上的纤维素绝缘层的老化条件是不均匀的。在这种情况下，传统的X模型被认为是不合适的，因为它忽略了非均匀热老化的影响。鉴于此问题，在这项工作中报告了一个修改的X模型。依靠修改后的X模型的理论分析，自然可以得出数学表达式和等效电路。实验研究证实了改进后的X模型的可靠性。此外，还研究了改进的X模型中的铝箔对FDS数据的影响。结果表明，添加铝箔会导致FDS曲线略有偏差。因此，修改后的X模型可用于研究非均匀热老化的信息。在这方面，这项工作的贡献在于探索了改进的X模型，这是一种潜在的工具，用于连接与实验室条件和现场条件相对应的FDS数据，包括套管芯上纤维素绝缘材料的不均匀热老化。结果表明，添加铝箔会导致FDS曲线略有偏差。因此，修改后的X模型可用于研究非均匀热老化的信息。在这方面，这项工作的贡献在于探索了改进的X模型，这是一种潜在的工具，用于连接与实验室条件和现场条件相对应的FDS数据，包括套管芯上纤维素绝缘材料的不均匀热老化。结果表明，添加铝箔会导致FDS曲线略有偏差。因此，修改后的X模型可用于研究非均匀热老化的信息。在这方面，这项工作的贡献在于探索了改进的X模型，这是一种潜在的工具，用于连接与实验室条件和现场条件相对应的FDS数据，包括套管芯上纤维素绝缘材料的不均匀热老化。

图形摘要