基于短时傅里叶变换的单相自适应重合闸技术

Single-phase adaptive reclosing technology based on short-time Fourier transform

高压输电线路上发生的故障大多为瞬时性的,为提高电力系统运行的稳定性以及供电的可靠性,自动重合闸技术是最为经济和有效的方法之一,但现有的自动重合闸技术带有一定的盲目性。为了解决自动重合闸技术的盲目性,自适应重合闸技术应运而生。自适应重合闸技术的关键在于如何在断路器断开之后到合闸之前的这段时间内判断出故障性质为瞬时性故障还是永久性故障。对于带有并联电抗器的输电线路,瞬时性故障消失后的恢复电压阶段会出现拍频现象,本文通过对恢复电压的拍频现象进行研究,利用短时傅里叶变换(short time Fourier transform,STFT),求出变换后的频谱图,并根据起拍电压时刻出现的频率特性,提出了一种基于短时傅里叶变换的单相自适应重合闸方法,并用电磁暂态仿真软件(electro magnetic transient in DC system/power systems computer aided design,EMTDC/PSCAD)建模仿真验证了该方法可以更好地识别故障的性质,实现自适应重合闸。

Most of the faults that occur on high-voltage transmission lines are instantaneous.In order to improve stability of the power system and reliability of power supply,automatic reclosing technology is one of the most economical and effective methods,but existing automatic reclosing technology has a certain degree of blindness.In order to solve the blindness of automatic reclosing technology,adaptive reclosing technology came into being.The key of adaptive reclosing technology is how to judge whether the fault is instantaneous or permanent during the period from the break of circuit breaker to the closing of circuit breaker.For transmission lines with shunt reactors,the beat frequency phenomenon will appear in the recovery voltage stage after the transient fault disappears.By studying the beat frequency phenomenon of the recovery voltage,the short-time Fourier transform is used to obtain the transformed spectrogram.According to the frequency characteristics at the moment of the starting voltage,a single-phase adaptive reclosing method based on short-time Fourier transform is proposed,and the EMTDC/PSCAD modeling simulation verifies that the method can better identify the nature of the fault,realizing self-adaptive reclosing.