In order to analyze low frequency oscillation of power system, this paper introduces a novel Wigner-Ville distribution (WVD) method based on EMD (Empirical Mode Decomposition), which is proposed to deal with non-stationary signal in the analysis of power system low frequency oscillations. The WVD method based on EMD can analyze local dynamic behavior and characteristics of nonlinear and non-stationary signals, get the oscillation mode parameters such as amplitude, frequency, damping ratio, phase, the time of starting and ending. It can reflect the time-varying behaviors of multi modes involved in oscillation process as well as their mutual influences better. Furthermore, the proposed method has the advantages such as high resolution and requiring short period of sample data, which can improve the identification capability and signal processing effect. Several experiments have validated the method; experimental results show that the method can identify the oscillation characteristics more accurately.%为了更加准确地进行电力系统低频振荡分析,引入了一种新的非线性、非平稳信号的处理方法-EMD(经验模态分解)的维格纳一威力分布(WVD)方法,通过EMD分解以及WVD算法处理分析非线性和非平稳电力信号的局域动态行为和特征,得到低频振荡的模态参数-振幅、频率、阻尼比、相位、开始与结束时刻.该方法准确地反映了系统所包含的多个振荡模式在时间上的变化规律以及模式之间的互相影响,并且有着高分辨率和有效地处理少量样本的短数据的优势,可提高识别能力和处理效果.通过多次试验表明该方法能够较准确地识别振荡特征.
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