电力系统低频振荡中的内共振现象研究

Study on Internal Resonance in Power System Low Frequency Oscillation

内共振是非线性多自由度系统自由振荡的种重要现象。基于内共振机理分析了电力系统低频振荡中的非线性因素影响和模式间的非线性相互作用。系统方程中的非线性项使得模式之间不能完全解耦,存在非线性相互作用,当频率关系合适时,非线性项使得被影响模式发生强迫振荡。电力系统低频振荡分析中要主要关注1:2和1:1内共振,并分析了电力系统中内共振发生的条件。仿真了内共振的具体算例,验证了所提出的内共振条件。内共振导致不同振荡模式间出现很强的非线性相互作用,使得系统的动态行为和线性化系统模态分析的结果存在很大差异,为电力系统中弱阻尼局部模式引发区间振荡等非线性特殊现象的分析提供了种新的机理和思路。

Internal resonance is an important phenomenon in the free oscillation of nonlinear multi-degree-of-freedom system. Based on the mechanism of internal resonance the impact of nonlinear factors in power system low-frequency oscillation and the nonlinear interaction among modes are analyzed. The nonlinear terms in system equation make the complete decoupling among modes disabled and it leads to the existence of nonlinear interaction, thus when the frequency relationship is adequate, the nonlinear terms induce forced oscillation of affected mode. During the analysis on power system low-frequency oscillation the main attention should be paid to the 1：2 and 1：1 internal resonance, and the conditions, under which the internal resonance in power system occurs, are analyzed. The cases of internal resonance are simulated and the proposed conditions of internal resonance are verified. Internal resonance leads to strong nonlinear interaction among different oscillation modes and make evident difference between the dynamic behavior of power system and the results of modal analysis of linearized system. This research offers a new mechanism and thinking for the analysis on nonlinear special phenomena such as inter-area oscillation caused by poorly damped local mode and so on.