发电机局部放电脉冲沿定子绕组传播规律的研究

RESEARCH ON PROPAGATION RULE OF PARTIAL DISCHARGE PULSES INSIDE GENERATOR ALONG STATOR WINDINGS

为研究发电机内部局部放电脉冲的传播规律,根据一实际50MW汽轮发电机定子绕组对方波、脉冲波和正弦波试验信号的响应结果,研究了2MHz以下频段试验脉冲沿定子线棒的传输线传播规律及信号幅值的变化规律、信号传播时延等;分析了2～6MHz和7～12MHz频段下试验脉冲沿定子绕组端部圆周传播的电容耦合机理及信号幅值的变化规律.发现了试验脉冲在三相绕组之间存在相互耦合的现象;2～6MHz频段下试验脉冲沿定子绕组端部圆周传播时幅值基本不发生衰减.这些研究结果将有助于理解局部放电信号在定子绕组中的传播规律,可为确定局部放电源所属相别甚至位置提供参考信息.

To reveal the propagation rule of the partial discharge (PD) pulses inside generator along its stator windings, according to the frequency response of the stator windings in actual turbo-generator with capacity of 50MW to the testing signals of square-wave, pulse-wave and sinusoidal wave, the propagation rule of the testing pulse within the frequency band lower than 2MHz along the stator winding bar and the variation law of signals' amplitudes and also time delay are researched. The capacitance coupling mechanism of the testing pulses, which are within the frequency range from 2MHz to 6MHz and that from 7MHz to 12MHz and propagate along the circumference enveloping the head of stator windings, and the variation law of their amplitudes are analyzed. Such phenomena has been observed, i.e., the testing pulses are intercoupled among the three phase windings and the amplitude of testing pulses within the frequency range from 2MHz to 6MHz are basically not attenuated when they transmit along the circumference enveloping the head of stator winding. These research results are conductive to understand the propagation rule of partial discharge signals along the stator windings, and are available for reference to determine the phase or the position that the PD source belongs to.