The reliable technique for identification of winding insulation faults in a transformer is necessary for a testing engineer during impulse test. In this study, a statistical correlation technique is proposed to estimate the ‘best correlation’ between transient signals for passed (withstood the impulse voltage) or failed (not withstood) conditions of the insulations. In this study, normalised reduced impulse voltage is considered initially as a reference signal. The next successive impulse test sequences due to rated test voltage are correlated as a test signal with a reference signal using a proposed technique. It makes a ‘good correlation value along with its directions’ between the reference signal and test signal based on measured the applied impulse voltage waveshape and its winding response. The fundamentals of the correlation coefficient, curve fitting techniques, conditional variance, normalisation and time delay index are integrated effectively to predict the characteristics (degree/magnitude and direction) of correlation between the signals. 2.5-MVA 11/0.433 kV (distribution transformer), 0.3-MVA 34.5/0.415 kV (earthing transformer) and 250-MVA 500/275/33 kV (power transformer) are effectively utilised to validate proposed technique. The advantage of the proposed technique is validated with partial discharge detection in windings due to an impulse voltage application using an 11 kV single-layer winding.

中文翻译：

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统计相关技术，用于变压器脉冲测试中的瞬态信号分析

在脉冲测试期间，测试工程师必须使用可靠的技术来识别变压器的绕组绝缘故障。在这项研究中，提出了一种统计相关技术来估计在绝缘的通过（承受脉冲电压）或失效（不承受）状况的瞬态信号之间的“最佳相关性”。在这项研究中，归一化的降低的脉冲电压最初被视为参考信号。使用提出的技术，将由于额定测试电压而产生的下一个连续的脉冲测试序列作为测试信号与参考信号进行关联。它基于测量的施加脉冲电压波形及其绕组响应，在参考信号和测试信号之间形成“良好的相关值及其方向”。相关系数的基本原理，曲线拟合技术，条件方差，归一化和时延指数有效地集成在一起，以预测信号之间相关性的特征（度/幅值和方向）。有效地利用了2.5-MVA 11 / 0.433 kV（配电变压器），0.3-MVA 34.5 / 0.415 kV（接地变压器）和250-MVA 500/275/33 kV（电力变压器）来验证所提出的技术。通过使用11 kV单层绕组施加脉冲电压，绕组中的局部放电检测可以验证所提出技术的优势。有效地利用415 kV（接地变压器）和250-MVA 500/275/33 kV（电力变压器）来验证所提出的技术。通过使用11 kV单层绕组施加脉冲电压，绕组中的局部放电检测可以验证所提出技术的优势。有效地利用415 kV（接地变压器）和250-MVA 500/275/33 kV（电力变压器）来验证所提出的技术。通过使用11 kV单层绕组施加脉冲电压，绕组中的局部放电检测可以验证所提出技术的优势。