尾水管空腔涡对抽水蓄能电站系统稳定性的影响北大核心CSCD

抽水蓄能电站在我国发展势头强劲,但发电工况中由尾水管空腔涡导致的机组功率振荡现象频发,严重危及电站和电网安全。本文为了研究空腔涡对输水发电系统稳定性的影响,从一维频域角度,分别构建了包括空腔涡在内的单管单机调节系统的传递函数和一洞两机系统的总体矩阵,并进行相应的稳定性计算分析。结果表明:与调速器影响相比,空腔涡影响对输水发电系统的稳定性起着决定性作用。当空腔涡诱发功率振荡时,系统不存在稳定域;当系统受到空腔涡影响却不足以发生功率振荡时,存在与无空腔涡时基本相同的稳定域。但空腔涡参数量级很小,随时可能因机组运行工况的变化而变化,进而诱发功率振荡。这为实际电站运行避免空腔涡引起系统失稳提供了理论依据。

Influence of cavity vortices in draft tube on system stability of pumped-storage power station

Pumped-storage power stations are promisingly developed in China, but they suffer unit power oscillation that, caused by cavity vortices in draft tube, occurs frequently in generating mode, severely threatening the safety of their operation and the power grid. To study the influence of such cavity vortices on the stability of a hydropower generating system, we construct a transfer function for the regulating system with a single unit and a global matrix for the system with two units sharing the same tunnel, from the perspective of one-dimensional frequency domain with consideration of the cavity vortices. Then, calculations and analysis of system stability are carried out for these two cases. The results indicate the influence of cavity vortices plays a decisive role in system stability in comparison with that of the governor. When power oscillation is induced by the cavity vortices, no system-stable region will exist; when the system is affected by the vortices but kept from power oscillation, its stable region is basically the same as that without the vortices. Nevertheless, the cavity vortices are usually characterized by small values of parameters that may change responding to the variations in unit operating conditions, and thus will result in power oscillation. This work highlights the role of draft tube cavity vortices to avoid system instability in the operation of hydropower stations.