基于自适应谱的局部放电信号时频特性分析

应用自适应谱对单个局部放电脉冲信号进行了时频特性分析，并与短时傅里叶变换谱、离散Wigner分布和Choi-Williams分布相比较，结果表明自适应谱上有能量集中、时－频域分辨率高、无交叉干扰项等优点，它能够细致刻画局部放电信号在时频平面上所发生的变化过程，准确反映出局部放电信号的时频特性，从而为局部放电信号的特征提取和模式识别开创了一条新的途径，对时频谱的分析还发现，局部放电信号的的频率分量达到GHz范围，这就为超高频和超宽频带局部放电检测的研究提供了理论依据。

Time-Frequency Analysis on Pulse Current of Partial Discharge by Adaptive Spectrogram

Pulse current of partial discharge (PD) is a non stationary signal, which has multi component harmonic terms and time varying spectrum. Using adaptive spectrogram (AS), the pulse current of PD was analyzed. For comparison, three joint time frequency analysis (JTFA) methods were used. They are short time Fourier transformation (STFT) based spectrogram, Wigner distribution (WD) and Choi Williams distribution (CWD). Results show that the AS has high resolution on both frequency domain and time domain without the cross term defects and that it can describe how the spectral content varies with time. So AS can be set as the reference of PD pattern recognition. The time frequency spectrum shows that the frequency spectrum of a PD signal contains harmonics up to 1 GHz, in some cases even higher than 1 GHz, which provides a reference for ultra high frequency (UHF) and ultra wide band (UWB) detection.