基于宽频等值电路的变压器局部放电电气定位研究

Research on localization of partial discharges in transformers based on wideband equivalent circuit

当变压器中发生局部放电时,脉冲电流信号会沿着绕组传播,检测绕组两端脉冲电流信号即可实现对变压器局部放电的检测。为此,建立变压器宽频等值电路模型,在可能发生局部放电的高压绕组处,于不同线饼与地之间施加局部放电脉冲,模拟高压绕组不同位置对地放电,在高压套管末屏及中性点处采集脉冲电流信号,研究不同位置局部放电脉冲电流信号在变压器绕组中的传播规律。通过计算可知,脉冲电流信号在两个不同频段能量占比的比值与脉冲电流传播的距离比呈线性关系,最大误差为9.80个线饼。该方法实现了变压器局部放电的电气定位,现场实验结果验证了该定位方法的有效性。

When partial discharge occurs within transformers,the pulse current signal propagates along the winding.Detecting this pulse current signal at both ends of the winding enables the identification of partial discharge within the transformer.To this end,a wideband equivalent circuit model for the transformer is established.In high-voltage windings where partial discharges are likely to occur,partial discharge pulses are applied between different wound disks and the ground to simulate the discharge to the ground at different locations of the high-voltage winding.Pulse current signals are then collected at the end screen of the high-voltage casing and at the neutral point to study the propagation rules of the partial discharge pulse current signal at different locations within the transformer windings.Through calculations,it is observed that the energy ratios of pulse current signals in two distinct frequency bands are linearly correlated with the distance ratio of pulse current propagation,and the maximum error observed in this context is 9.80 wound disks.This method facilitates localization of partial discharge within the transformer,and the results of field experiment subsequently validate the effectiveness of this localization technique.