基于短时Fourier变换的变压器绕组变形脉冲频率响应曲线获取方法

Method for Obtaining the Impulse Frequency Response Curves of Power Transformer Winding Deformation Based on Short Time Fourier Transform

为了在利用脉冲注入法在线检测电力变压器绕组变形故障时能正确处理暂态信号,获取绕组的脉冲频率响应曲线,避免绕组变形状态的误判,提出了基于短时Fourier变换的脉冲频率响应曲线获取新方法,对该方法的基本原理进行了理论推导。然后,从理论推导入手,构建了单绕组仿真模型,结合PSPICE和MATLAB进行了联合仿真分析。仿真结果表明该仿真模型下经过短时Fourier变换的频率响应曲线谐振频率位于2 MHz,接近传统正弦频率响应曲线的谐振频率,初步证实了该方法的正确性。最后开展了110 k V变压器试验测试,分别用快速Fourier变换(FFT)和短时Fourier变换(STFT)处理了测试数据,采用相关系数指标进行了分段评判。试验结果表明经过短时Fourier算法处理后,绕组间频率响应曲线相关系数均>3,频率响应曲线清晰度较高,比快速Fourier变换处理效果更好。仿真分析与试验测试的数据处理结果均表明了该方法的可行性和优越性。

In order to process transient signal, obtain the correct impulse frequency response curves, and avoid misjudg- ment of winding status when the pulses injection method is used to online detect power transformer winding deformation,we proposed a new method for obtaining the impulse frequency response curves based on short time Fourier transform （STFT）, constructed a single transformer winding model after theory deduction,and adopted PSPICE and MATLAB software to perform simulations. The results show that, in this simulation model, the resonant frequency of STFT-based frequency response curve is located in 2 MHz, which is closer to the resonant frequency of conventional sweep frequency response curves. The simulation results validate correctness of the proposed method. Finally, the expe- rimental test has been carried out in a 110 kV power transformer, the experimental data have been processed by fast Fourier transform （FFT） and STFT, respectively, and the correlation coefficient is selected as an indicator. The results show that, after the processing of STFT, the correlation coefficient of frequency response curves is higher than 3, and these curves are clearer, thus the processing is more effective than that of FFT. The data processing results of simulation analysis and experimental test verify the feasibility and superiority of the proposed method.