蓄能机组水轮机工况开停机过程现场测试分析

Field Test Analysis of Start-stop Process of Turbine Operating Condition of Pumped Storage Power Unit

摘要:

抽水蓄能电站作为一种重要的储能技术，兼具水泵和水轮机两种工作方式。为了满足能源收集和电网调度要求，水泵水轮机工况转换频繁，开停机次数增加，机组的不稳定问题突出。由于缺乏机组机械动作中压力等运行参数的详细认识，边界条件的设置不同于实际运行工况，造成现场测试与数值模拟、模型试验存在差异，尤其是开停机暂态过程中机组特征参数复杂性增加。针对某原型蓄能机组进行现场测试，对机组各部件安装压力和加速度传感器以获得压力信号和振动加速度信号，基于现场收集的试验数据，分析了机组在水轮机工况开机和停机过程的运行特性。结果表明：水轮机开机过程，开机瞬间稳定性较好，之后转轮加速阶段机组压力脉动表现为宽频噪声，转轮减速阶段压力脉动表现为叶轮旋转频率及其倍频。固定导叶开度空载下，机组各测点周期性压力振荡消失并伴随混频幅值变化。调速器动态模式下，机组频率成分以自然频率为主。水轮机停机过程，压力脉动对导叶动作不敏感，随转速减小脉动强度逐渐下降。下机架和顶盖受机械动作的影响振动较强，之后会随着转速减小而下降。蝶阀关闭后依然存在与转速变化无关的顶盖模态频率线。

Abstract:

As an important energy storage technology, pumped storage power plants have both pump and turbine operating modes. In order to meet the requirements of energy collection and grid scheduling, the pump turbine operating conditions change frequently, the number of start-ups and shutdowns increases, and the instability of the unit is prominent. Due to the lack of detailed knowledge of the operating parameters such as pressure in the mechanical action of the unit, the boundary conditions are set differently from the actual operating conditions, resulting in the discrepancy between the field test and the numerical simulation and model test, especially the increase in the complexity of the unit’s characteristic parameters during the start-stop transient process. A prototype energy storage unit was tested in the field, and pressure and acceleration sensors were installed on each component of the unit to obtain pressure signals and vibration acceleration signals, and based on the experimental data collected in the field, the operating characteristics of the unit were analyzed in the start-up and shutdown processes of the turbine operating conditions. The results showed that during the hydraulic turbine start-up process, the instantaneous stability of the start-up was good, after which the pressure pulsation of the unit during the runner acceleration stage was manifested as a broadband noise, and the pressure pulsation during the runner deceleration stage was manifested as the impeller rotational frequency and its octave frequency. Under no load with fixed guide vane opening, the periodic pressure oscillations at each measurement point of the unit disappeared which accompanied by changes in the amplitude of the mixed frequency. Under the governor dynamic mode, the frequency component of the unit was dominated by the natural frequency. During the turbine shutdown process, the pressure pulsation was insensitive to the guide vane action, and the intensity of the pulsation was gradually decreased with the speed reduction. The lower frame and top cover vibrated more strongly by the mechanical action, after which they were decreased with the decrease of rotational speed. The top cover modal frequency line, which was independent of the speed change, still existed after the butterfly valve was closed.