It is important to determine the transient stresses at large power transformer winding terminals because this transient stress may induce power transformer failure. When a transient sensor is mounted inside the transformer, there is a potential discharge from the high-voltage conductor to the sensor. Therefore, the transient voltages in transformers are usually measured indirectly. Such measurement results are not accurate because they are affected by the structure and impedance of the power equipment. Thus, a built-in capacitive fast transient sensor (FT sensor) was developed in this article. The developed sensor was installed inside the bushing mounting; thus, transient voltages are directly obtained. To eliminate potential discharge from a high-voltage conductor to a transient sensor, a dielectric window (DW) was developed. Then, the effects of the DW and transformer oil on the amplitude–frequency response of the sensor were investigated. The results indicate that the bandwidth of the developed sensor spans 11 Hz–86.6 MHz (±1 dB). Afterward, switching and lightning impulse tests were conducted to demonstrate the accuracy of the sensor. Moreover, the proposed sensor was used to investigate the transient overvoltage in a 500-kV pumped storage power plant. The transformer winding exhibits increased stress due to the influence of frequent resonant transients with high amplitudes.

中文翻译：

---

基于内置电容传感器的变压器端快速瞬态测量

确定大型电力变压器绕组端子处的瞬态应力非常重要，因为这种瞬态应力可能会导致电力变压器故障。当瞬态传感器安装在变压器内部时，高压导体到传感器之间存在电位放电。因此，变压器的瞬态电压通常是间接测量的。这样的测量结果并不准确，因为它们受到电力设备的结构和阻抗的影响。因此，本文开发了一种内置电容式快速瞬变传感器（FT传感器）。开发的传感器安装在套管安装内部；这样就可以直接得到瞬态电压。为了消除从高压导体到瞬态传感器的潜在放电，开发了介电窗 (DW)。然后，研究了 DW 和变压器油对传感器幅频响应的影响。结果表明，所开发的传感器的带宽范围为 11 Hz–86.6 MHz (±1 dB)。随后，进行了开关和雷电冲击测试，以证明传感器的准确性。此外，所提出的传感器还用于研究 500 kV 抽水蓄能电站的瞬态过电压。由于频繁的高振幅谐振瞬变的影响，变压器绕组表现出增加的应力。