变压器绕组对局部放电电磁波传播特性的影响
Simulation Analysis of Effects of Transformer Windings on Propagation Characteristics of Partial Discharge Electromagnetic Waves

为了研究变压器绕组对局部放电电磁波传播特性的影响,根据一台330 kV变压器绕组的实际结构,建立了变压器绕组仿真计算模型。采用时域有限差分法(FDTD)研究了局部放电发生在绕组内部和外部时,变压器绕组对电磁波时域波形幅值的衰减规律,以及在相同的条件下绕组对局部放电电磁波频谱分布的影响,并通过与无障碍空间中传播时局部放电电磁波的频率特性进行对比,得到了局部放电电磁波不同频率段的频率幅值和,及其在总频率幅值和中所占的比例。研究发现:绕组对内部放电和外部放电产生的局部放电电磁波传播特性的影响不同,绕组对内部放电产生的不同频率段电磁波的幅值有增强的作用,而且对1 000～2 500 MHz高频段的增强作用比其他频率段强;绕组对外部放电产生的电磁波幅值有较强衰减作用,穿过绕组后电磁波的幅值至少衰减为无障碍空间时幅值的70％。
A simulation model for transformer windings is proposed to study the effect of the transformer windings on the propagation of electromagnetic (EM) wave induced by partial discharge (PD). The study is based on the size of windings in a 330 kV power transformer. A finite difference time domain (FDTD) method is used to analyze the propagation of PD EM wave in both internal and external windings. The effect of transformer windings on the propagation characteristics of PD electromagnetic waves is studied by applying PD pulse current signals in different places. This model is also used to study the effect of winding structures on the frequency spectrum of PD electromagnetic waves. The sum of the peak amplitudes in different bands and their proportions in the total sum are calculated through dividing the frequency spectrum into different bands. The calculation results are compared with those obtained in the places with and without obstacles (windings). It is found that the effects of transformer windings on the propagation characteristics of typical partial discharge electromagnetic waves are different in different places, and that the propagation characteristics depend on the location of PD according to windings. Windings increase the amplitude of EM waves from internal PD, especially in the frequency band 1 000 MHz？？2 500 MHz; and make a strong attenuation of 30% on the amplitude of EM waves from external PD