电力系统振荡信号瞬时幅值/频率的调制特征分析

Modulation Characteristics Analysis for Instantaneous Amplitude/Frequency of Power Systems Oscillation Signals

电力电子装备广泛应用引发的复杂振荡问题给电力系统的安全稳定运行带来了挑战,分析振荡过程中的信号特征是认识振荡形成并进行振荡抑制的重要基础。然而传统基于恒定幅值/频率谐波叠加的信号分析方法难以描述实际振荡信号的非平稳时变规律。因此站在幅值和频率视角下提出一种反映振荡信号瞬时幅值/频率调制特征的信号分析方法。首先基于系统振荡的物理过程认识了振荡信号形成过程中幅频调制的基本特点;其次根据信号形成特点提出描述振荡信号特征的解析表达式,并设计了一种提取表达式中幅频调制特征量的估计方法;最后通过算例分析验证了估计方法的有效性,特征提取结果揭示了振荡信号瞬时幅值/频率的调制变化规律。

The complex oscillations caused by the large-scale applications of power electronics equipment have brought great challenges to the safe operation of power systems, so analyzing the features of the oscillation signals is an important basis for understanding the oscillation process and restraining the oscillation. However, it is difficult for the traditional signal analysis based on the constant amplitude/frequency harmonic superposition to describe the non-stationary time-varying regularity of the actual oscillation signals. Thus, a signal analysis is proposed in this paper reflecting the instantaneous amplitude(IA) and instantaneous frequency(IF) modulation characteristics of the oscillation signals from the perspective of the amplitude and frequency.First, the amplitude/frequency modulation features in the process of the signal formation are revealed based on the essence of the oscillation amplitude/frequency modulation.Second, according to the features of the signal formation, an expression to describe the oscillation signal analytically is proposed. Besides, the estimation method is designed to extract the amplitude-frequency modulation characteristic quantity.Finally, examples are given to verify the effectiveness of the method. The results depict the amplitude/frequency modulation rules of the oscillation signals.