The reliable moisture determination in a power transformer is still a challenge for utilities and large power transformer operators. The presence of high moisture can cause serious problems, such as severely reducing the remaining useful life and the operational capability of a transformer. The large insulation structure and slow dynamic moisture migration between cellulose and insulating fluid make it difficult to determine the true moisture level. Fiber optics based sensors offer superior sensing characteristics as compared with other techniques. A key advantage of using fiber optic sensors is their ability to be inserted into the winding structure. However, this is a relatively new technology and so extensive research and testing is required to understand how their measurement is affected by the operation of a transformer, and in particular by any sudden changes during a stepped load. In this work, the application of optical fiber Bragg grating based sensors is investigated under the influence of step cyclic thermal loading condition. The test is similar to the test performed by CIGRE WG D1.52 for evaluating different capacitive water activity probes. The tested optical sensors, coated with polyimide material for moisture sensing, are found to be suitable in comparison with commercial sensors and can be effectively used for moisture measurements in different insulated transformers.

中文翻译：

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使用光学传感器在变压器绝缘中进行高级在线水分测量

电力变压器中可靠的水分测定对于公用事业和大型电力变压器运营商来说仍然是一个挑战。高水分的存在会导致严重的问题，例如严重降低变压器的剩余使用寿命和运行能力。纤维素与绝缘液之间较大的绝缘结构和缓慢的动态水分迁移使得很难确定真实的水分含量。与其他技术相比，基于光纤的传感器具有卓越的传感特性。使用光纤传感器的一个关键优势是它们能够插入到绕组结构中。然而，这是一项相对较新的技术，因此需要进行广泛的研究和测试，以了解变压器的运行对它们的测量有何影响，尤其是在阶跃负载期间的任何突然变化。在这项工作中，研究了基于光纤布拉格光栅的传感器在步进循环热载荷条件的影响下的应用。该测试类似于 CIGRE WG D1.52 为评估不同电容水活度探针而进行的测试。经测试的光学传感器涂有聚酰亚胺材料以进行湿度传感，与商用传感器相比更适用，可有效用于不同绝缘变压器中的湿度测量。52 用于评估不同的电容水活度探针。经测试的光学传感器涂有聚酰亚胺材料以进行湿度传感，与商用传感器相比更适用，可有效用于不同绝缘变压器中的湿度测量。52 用于评估不同的电容水活度探针。经测试的光学传感器涂有聚酰亚胺材料以进行湿度传感，与商用传感器相比更适用，可有效用于不同绝缘变压器中的湿度测量。