HHT在电力系统低频振荡模态参数提取中的应用

Application of HHT for Extracting Model Parameters of Low Frequency Oscillations in Power Systems

针对目前电力系统低频振荡的分析局限于用线性化方法来处理而导致的分析结果不精确,甚至不尽合理,提出基于希尔伯特–黄变换(HHT)的提取电力系统低频振荡模态参数新方法。首先运用HHT中的经验模态分解(EMD)实现各低频振荡模态分量的有效分离,并对各模态分量进行希尔伯特(Hilbert)变换、计算其相对应瞬时幅值、瞬时频率及相位;其次运用该文推导的阻尼比计算公式提取各振荡模态分量阻尼比,从而实现低频振荡模态参数的有效提取。同时对超低频振荡的产生机理给出一种新的解释,该方法有助于分析电力系统强非线性振荡模态及阻尼控制器的设计研究。数值仿真及实例分析均表明该方法的可行性和有效性。

In order to obtain reasonable and precise results in analyzing low frequency oscillation （LFO） in power systems, a novel method based on Hilbert-Huang transform （HHT） was introduced to extract the model parameters of LFO. It applied empirical model decomposition （EMD） to decompose the LFO signals and calculated the instantaneous parameters including magnitude, frequency and phase of every model component with Hilbert transformation, and then calculated the damping ratio of every model component based on above parameters and derived the formulas. Thus it realized effective extraction of all parameters of LFO signals and put forward a new explanation of the mechanism of very low frequency oscillation. This method can be applied to analyze strong non-linear oscillation models in power systems and design damping controllers. The simulations and example analysis indicate the feasibility and validity of the new method proposed in this paper.