基于小波分析的空心电抗器匝间短路磁场探测方法研究

Detection method of inter-turn short-circuit magnetic field of air-core reactor based on wavelet analysis

为了解决目前干式空心电抗器匝间短路检测方法灵敏度和准确度不足的问题,根据故障发展期探测线圈感应电压的异常变化,提出一种新的基于小波分析的空心电抗器匝间短路磁场探测方法。首先,对电抗器故障发展期探测线圈电压信号进行仿真分析,得到电抗器不同位置匝间短路时探测线圈信号变化特征。再基于信号分解小波系数中有用信号与噪声相对比值最大的原则,逐层自适应选取最优小波基函数,利用小波变换对信号进行阈值去噪,提取故障特征量从而实现对电抗器匝间短路发展期及时准确地判断,避免故障进一步发展。通过搭建电抗器匝间短路故障检测系统实验平台,验证了基于小波分析磁场探测法的灵敏度和可靠性,为电抗器的安全稳定运行提供有效保障。

To solve the problem of insufficient sensitivity and accuracy of the current dry-type air-core re-actor inter-turn short-circuit detection method,according to the abnormal change of the induced voltage of the detection coil during the fault development period,a new method based on wavelet analysis was pro-posed to detect the inter-turn short-circuit magnetic field of the air-core reactor.Firstly,the voltage signal of detecting coil in the reactor fault development stage was simulated and analyzed,and the signal varia-tion characteristics of detecting coil in the short circuit between turns at different positions of the reactor were obtained.Based on the principle that the relative ratio between useful signal and noise is the largest in the wavelet coefficient of signal decomposition,the optimal wavelet basis function was selected layer by layer adaptively.The wavelet transform was used to de-noise the signal threshold value,and the fault characteristic was extracted so as to timely and accurately judge the development period of the short cir-cuit between turns of the reactor and avoid the further development of the fault.The sensitivity and relia-bility of the magnetic field detection method based on wavelet analysis were verified by building an experi-mental platform for the detection of inter-turn short-circuit fault of the reactor,which provided an effective guarantee for the safe and stable operation of the reactor.