混流可逆式机组工况变换过程导叶小开度区流动控制研究

In a pumped storage power station, the units may produce vibration and noise at times when the guide vanes rotate into the small opening region(less than 10% of the maximum opening) in the operating condition transition, such as shutdown and startup in pumping mode, shutdown in turbine mode. The unsteady flow calculation in the pump turbine is coupled with the transient simulation of the power station to realize the simulation of the unsteady flow in the guide vanes, when they are opened or closed in the condition transformation. The flow rate and the hydraulic torque in the guide vanes are studied, combined with the hydraulic vibration analysis of pipeline system in the power station. The reason is exposed how the vibration and noise is induced by the instability of the flow in the guide vanes. Based on these, the influence on the flow pattern in the guide vanes of the process control and the guide vane profile is researched, and the optimum process control method and the design criteria of guide vane are presented to improve the flow stability in the small guide vane opening. The design and control theory of the pumped storage power station is deepened and perfected to improve the operation stability, which is contribute to the development of the pumped storage power station in our country.

本项目针对抽水蓄能电站机组在抽水停机、抽水调相转抽水及发电停机等工况变换过程中在导叶小开度区(小于10%最大开度)可能出现的异常声响和水力振动问题，将机组内部流动计算和电站过渡过程计算相结合，实现工况变换过程导叶开启和关闭的暂态流场计算，研究导叶间流速和作用在导叶上水力矩的变化规律，并与电站管道系统水力振动分析相结合，揭示流动不稳定引起导水机构产生异音和振动的原因，在此基础上通过研究电站工况变换过程控制措施和导叶形状对导叶间流态的控制和改善作用，提出改善系统运行稳定性的控制措施和导叶叶型设计原则，深化和完善抽水蓄能电站系统和机组的设计和运行控制理论，提高电站的运行稳定性，为我国今后的抽水蓄能电站发展做出贡献。

本项目针对抽水蓄能电站机组在抽水停机、抽水调相转抽水及发电停机等工况变换过程中在导叶小开度区(小于10%最大开度)可能出现的异常声响和水力振动问题，将机组内部流动计算和电站过渡过程计算相结合，实现工况变换过程导叶开启和关闭的暂态流场计算，提出导叶间流态区划分方法，研究了双向启停、工况转换等过程中机组内部流动状态的变化规律，揭示了抽水过程中导叶间“双稳态”流动、发电停机过程中水流流向反复逆转是导致微小开度下导水机构产生振动、出现异音的水动力根源。引入导叶水力矩变化率定量地表征导叶间流态变化的剧烈程度和异音产生的可能性，归纳了异音产生频率和运行水头（或扬程）的相关关系，研究成果与电站统计数据相比较，二者吻合。基于阻抗法建立了复杂管道系统电站水力振动分析软件，对电站管道系统进行了水力振动分析，导叶处可能出现的柔性阀门特性是导致系统自激振动的原因。基于对微小开度下活动导叶间不稳定流动与开度、来流角等参数相关关系的深入研究，提出了抽水停机提前断电、进水球阀和活动导叶协调动作以改善导叶间流动稳定性的两种过程控制方案，并对导叶开度等重要控制参数进行了优化；提出了适当增大密合角和减小渐扩比以抑制抽水过程中双稳态流动诱发导水机构产生振动的导叶修型措施。通过数值模拟的方法验证了各控制方案的有效性。