水电机组流激振荡数值仿真

Numerical Simulation of the Flow-Induced Oscillation of Hydropower Units

四川省某大型水电站机组运行过程中出现了持续性有功功率超低频振荡的现象,振荡周期低于0.1Hz。经现场试验,排除了机组调速、励磁、一次调频等非水力因素和电站上游侧的影响,超低频振荡的诱导因素初步判定为该电站“一洞多机”明满流尾水系统在特定运行工况下的水力不平衡现象。为进一步分析超低频振荡现象产生的具体原因,采取电路等效法建立电站明满流尾水系统高阶数学模型,并对系统进行特征频率分析,获取该系统的各阶特征频率分布。此外,通过改变模型中尾水流道参数,进行不同工况下的系统时域仿真,探索关键节点处水力波动的变化规律,寻求抑制超低频振荡的合理解决方案。

The continuous ultra-low frequency oscillation of active power occurred during the operation of a large hydropower station in Sichuan Province,with the oscillation period less than 0.1Hz.Through the field test,the influence of non hydraulic factors such as unit speed regulation,excitation,primary frequency regulation and the upstream side of the power station has been eliminated.The inducing factor of ultra-low frequency oscillation is preliminarily determined as the hydraulic imbalance of the“one tunnel with multiple turbines”open and full flow tailrace system of the power station under specific operating conditions.In order to further analyze the specific causes of ultra-low frequency oscillation,the circuit equivalent method is adopted to establish a higherorder mathematical model of the power station open and full flow tailrace system,and the characteristic frequency of the system is analyzed to obtain the characteristic frequency distribution of each order of the system.In addition,by changing the parameters of the tailrace channel in the model,the time domain simulation of the system under different working conditions is carried out to explore the change law of hydraulic fluctuations at key nodes and find a reasonable solution to restrain ultra-low frequency oscillation.