振荡源和振荡起因问题是目前共振型低频振荡研究的主要问题。通过对汽轮发电机组功频调速控制机制和阻尼分析发现，当电网侧发生功率扰动时，实际的功频控制方式使机械功率阻尼降低。在扰动初期，机械功率出现“反调”，快速激发振荡；当扰动频率接近共振频率时，会引发机械功率共振。基于典型参数模型的仿真研究证实了上述分析的正确性，此外，还表明若系统中某些机组共振频率相近，在小扰动下引起的振荡可能在机组间耦合放大。研究结果对完善共振型低频振荡的机制研究、改进实际的汽轮机功频调速控制和调试方法及抑制电力系统低频振荡有重要的现实意义。

The source and cause of oscillation are studied as the main problem for the resonance-type low-frequency oscillation at present. Through the analysis of power-frequency rotate speed regulation mechanism and damping of turbo- generators, it can be concluded that practical power-frequency control mode makes mechanical power damping decrease when network side power disturbance occurs; “inverse regulating” of mechanical power will happen at the beginning, and initiate oscillation rapidly; when disturbance frequency is close to resonance frequency, mechanical power resonance will be triggered. Simulation research based on the typical parameters model demonstrates the above analysis is correct, and oscillation of some machine initiated by small disturbance may be coupled and amplified between generating units if resonance frequencies of generating units are close to each other. The research is practically significant for promoting the mechanism research of resonance-type low-frequency oscillation, improving practical power-frequency rotate speed control and debugging methods of steam turbines, inhibiting low-frequency oscillation in the power system.

湖南省教育厅资助科研项目(04C092)。