基于新型内置光纤F-P传感器变压器局部放电故障定位方法的研究

Partial discharge (PD) is one of the main signs of defects and degradation of the insulation of power transformer. It is essential to detect PD sensitively and locate PD source accurately to avoid unwanted failure of transformers. Acoustic emission-based location method has been studied and applied on a large scale both in the domestic and foreign presently. According to the method, acoustic signals generated by PD is detected employing piezoelectric acoustic emission sensors placed outside the transformer tank wall. However in some applications, this method is not very effective, typically as a result of the inaccuracy of the detected signal, the low sensitivity and anti-interference, the insufficient knowledge of the law of acoustic wave propagation in transformer tank, as well as the faultiness of location algorithm. This application presents a new built-in optical fiber F-P sensor which improved the sensitivity and accuracy of transformer partial discharge detection. Through the simulation calculation and experimental research on large computer, the law of acoustic wave propagation in transformer tank is discussed and the algorithm of PD fault location is proposed. Thus, the accurate fault location on power transformer partial discharge online monitoring is realized, which will greatly improve the transformer fault monitoring and diagnosis level and be of great scientific significance.

局部放电是电力变压器绝缘缺陷和劣化的主要标志之一，如何准确检测到局部放电，确定放电源的位置，是变压器故障诊断的重要课题。目前, 国内外研究和应用最多的是超声波定位法，采用压电超声传感器在变压器外侧箱壁上检测局部放电超生波信号，因测到的信号不够准确，其灵敏度和抗干扰性也不够高，同时对超生波在变压器箱体中的传播规律了解的不够深入，各种计算定位法中的算法也不尽完善，使得定位效果并不十分理想。本申请采用新型内置光纤F-P光学传感器，在提高变压器局部放电检测灵敏度和准确性的同时，通过在大型计算机上进行仿真计算和试验研究，掌握变压器局部放电超生波在变压器箱体中的传播规律，提出故障定位的算法，实现对变压器局部放电在线监测中故障的准确定位，该目标的实现将大大提高变压器故障监测和诊断水平，具有重要的科学意义。

本项目对高压电力变压器内部的局部放电超声信号定位展开了研究，研制了压强平衡结构EFPI传感器，实现了高压力、高温度等恶劣条件下的局部放电超声检测，避免封闭式F-P腔的初始工作点受外界环境的影响，其工作点具备较强的稳定性，并将新型传感器应用于变压器内部局部放电定位中。深入探索变压器内部局部放电超声信号的传播规律，根据有限元法对变压器中超声波传播规律进行仿真，揭示了变压器内部复杂结构对局部放电超声信号传播的影响。提出基于SRP算法和光纤EFPI超声传感器阵列的油中局部放电定位，实现了用较少传感器阵元进行油中局部放电的定位，首次提出将8个传感器分层均匀布置在变压器高、低压绕组中间的油道中，利用到达时间差算法进行定位，分别对高压绕组匝间、低压绕组匝间、油道中的局部放电超声信号进行了仿真和试验定位，实验室定位误差小于5cm，为变压器绕组内部局部放电信号的检测和定位提供了一种新的方法。较好的完成了本项目的各项任务，达到了预设目标。