中文摘要：

为了分析区域内集中的大量小水电机组所产生的群集效应以及这些机组之间的弱阻尼振荡模式引发主网强迫功率振荡的风险,以湖北恩施地区小水电机群为研究对象,在某年度湖北电网丰水大负荷运行方式模型的基础上,分析了恩施地区小水电机组采用详细模型时,华中—华北主网以及特高压联络线的低频功率振荡特性,结果表明：恩施地区小水电机群内部存在阻尼比接近3%的弱阻尼振荡模式,并且这些发电机参与了三峡机组主导的振荡模式;进一步的仿真研究表明,在某些特殊情况下小水电机群可诱导主网产生上百MW的强迫功率振荡;针对该现象文中提出了一种振荡传播路径图用于指明振荡向外传播扩散的路径与影响范围,分析表明其对三峡以及特高压电网的影响比较小。

英文摘要：

In order to analyze the cluster effect of massive small hydroelectric generators grouped in an area and to evaluate the risk of forced power oscillation in main grid caused by the weak damping among small hydroelectric generators, taking small hydroelectric generator cluster in Enshi of Hubei province as a research example, we analyzed the low frequency oscillation characteristic of centre China and North China power grid and ultra high voltage（UHV） AC transmission lines when the generator cluster adopted the detailed model. Simulation results show that there is a weak oscillation mode with the damping ratio close to 3% among the small hydroelectric generators in Enshi, and those generators also participate in the oscillation mode leaded by the generators in Three Gorges power plant. Through further simulation, it is verified that the small hydroelectric generator cluster will induce forced power oscillation with amplitude up to hundred MW in main grid in some special cases. Thereby, we used an oscillation spreading figure to analyze the propagation path and the impact of the oscillation.The results show that the oscillation induced by the small hydroelectric generator cluster in Enshi has small influences on the Three Gorges power plant and the UHV power grid.