Kunakorn Anantawat, Pramualsingha Sarawuth, Yutthagowith Peerawut, Nimsanong Phethai, Kittiratsatcha Supat
School of Engineering, King Mongkut's Institute of Technology Ladkrabang, Bangkok 10520, Thailand.
Power System Analysis Section, Power System Control Department, Metropolitan Electricity Authority, Bangkok 10330, Thailand.
Sensors (Basel). 2023 Oct 3;23(19):8236. doi: 10.3390/s23198236.
Power transformers are essential apparatuses used to transfer electrical energy from one voltage-level circuit to another. For reliable systems, preventive maintenance of the transformers is required to ensure good services of all mechanical, electrical, and insulation parts. Oil-immersed paper is most often used for transformer insulation. To ensure such good insulation performance and for assessing insulation conditions, advanced transformer sensing, monitoring, and effective assessment techniques are required. This paper introduces an effective technique for assessing the insulation conditions in power transformers, which are crucial for ensuring reliable energy transfer. The method utilizes advanced transformer sensing and monitoring, focusing on oil-immersed paper insulation commonly used in transformers. The technique employs dielectric response sensing, obtained from frequency-domain spectroscopy tests, to estimate degrees of polymerization (DP) and percentages of moisture content (PMCs) in the oil-immersed paper insulation. These parameters are well-known indicators of insulation performance. The approach is based on the weighted k-nearest neighbor regression, using a database of dielectric loss factors at low frequency and oil conductivities. To overcome limited data availability, linear interpolation and extrapolation techniques are applied to enlarge the database. Experimental verification and comparison with a previously developed method demonstrate the proposed technique's superiority in accuracy and complexity. The maximum deviations of DP and PMC in the validation cases are 6.2% and 18.7%, respectively. In addition, to evaluate the validity of our proposed method in the case of a real power transformer, a comparative analysis of the DP and PMC values determined by the proposed method with those obtained through a previously developed and complicated approach was performed. The predicted results indicate that the DP and PMC values of the oil-immersed insulation fall within the ranges of 800 to 1000 and 1.5 to 2.0, respectively, which agree with the results determined by the complicated approach and closely align with real conditions. By offering a reliable and advanced means of assessing insulation conditions, this technique contributes to the preventive maintenance and overall efficiency of power transformers.
电力变压器是用于将电能从一个电压等级的电路传输到另一个电压等级电路的关键设备。对于可靠的系统而言，需要对变压器进行预防性维护，以确保所有机械、电气和绝缘部件都能良好运行。油浸纸最常用于变压器绝缘。为确保良好的绝缘性能并评估绝缘状况，需要先进的变压器传感、监测和有效评估技术。本文介绍了一种评估电力变压器绝缘状况的有效技术，这对于确保可靠的能量传输至关重要。该方法利用先进的变压器传感和监测技术，重点关注变压器中常用的油浸纸绝缘。该技术采用从频域光谱测试获得的介电响应传感来估计油浸纸绝缘中的聚合度（DP）和水分含量百分比（PMC）。这些参数是众所周知的绝缘性能指标。该方法基于加权k近邻回归，使用低频介电损耗因数和油电导率的数据库。为克服数据可用性有限的问题，应用线性插值和外推技术来扩大数据库。实验验证以及与先前开发的方法进行比较，证明了所提出技术在准确性和复杂性方面的优越性。验证案例中DP和PMC的最大偏差分别为6.2%和18.7%。此外，为评估我们提出的方法在实际电力变压器情况下的有效性，对通过所提出方法确定的DP和PMC值与通过先前开发的复杂方法获得的值进行了比较分析。预测结果表明，油浸绝缘的DP和PMC值分别落在800至1000以及1.5至2.0的范围内，这与复杂方法确定的结果一致，并且与实际情况紧密相符。通过提供一种可靠且先进的评估绝缘状况的方法，该技术有助于电力变压器的预防性维护和整体效率提升。
