Review of hydrodynamics instabilities in Francis turbine during off-design and transient operations
Review of hydrodynamics instabilities in Francis turbine during off-design and transient operations
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DOI：
10.1016/j.renene.2017.10.012
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发表时间：
2018-02
期刊：
影响因子：
8.7
通讯作者：
R. Goyal;B. Gandhi
中科院分区：
文献类型：
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作者：
R. Goyal;B. Gandhi
太阳能和风能发电引起了人们对电网稳定性的极大担忧。水电对电网的稳定起着重要的平衡作用。为了提高当前高负荷电网的稳定性，水电站的运行范围很广，并经历了频繁的启停、负荷变化和紧急停机。包括水轮机在内的发电机组需要承受运行状态的突变，以平衡电网频率。本文的目的是介绍混流式水轮机在当前能源发电方案中的运行问题。汽轮机在变工况和暂态运行过程中存在多个动态不稳定问题。在稳态和暂态运行条件下，都观察到了几个低频和高频压力波动。非设计操作，如部分加载和高加载，会由于RSI、RVR和汽蚀而引起压力波动。瞬时运行导致其运动部件和静止部件承受较大的循环载荷。混流式水轮机还会承受转轮上的不对称载荷、循环应力、磨损；所有这些都会降低部件的使用寿命。有时，这些快速瞬变可能会导致机组故障并使其与系统解耦。
Electricity generation from solar and wind has raised a significant concern about the stability of grid networks. Hydroelectricity plays an important role to balance the stability of grid network. In order to improve the stability of presently high loaded grids, hydropower plants are being operated over a wide range of operations and experiencing frequent start-stop, load variation, and emergency shutdown. The power generating unit including turbine needs to sustain sudden change in its operating condition to balance the grid frequency. The objective of this paper is to present the operating problems of Francis turbine in the present energy generation scenario. The turbine suffers from several dynamic instabilities during off-design and transient operations. Several low and high-frequency pressure fluctuations are observed during both, steady state and transient operating conditions. The off-design operations such as part load and high load cause pressure fluctuations due to RSI, RVR and cavitation. The transient operations lead to heavy cyclic loading of its moving and stationary parts. Francis turbine also experiences asymmetric loading on the runner, cyclic stress, wear and tear; all of which reduce operating life of the components. Sometimes these rapid transient may cause failure of the unit and decouple it from the system.