Penetration of the power generated using wind and solar energy to electrical grid network causing several incidents of the grid tripping, power outage, and frequency drooping. This has increased restart (star-stop) cycles of the hydroelectric turbines significantly since grid connected hydroelectric turbines are widely used to manage critical conditions of the grid. Each cycle induces significant stresses due to unsteady pressure loading on the runner blades. The presented work investigates the pressure loading to a high head (H _P = 377 D _P = 1.78 m) Francis turbine during start-stop. The measurements were carried out on a scaled model turbine (H _M = 12.5 D _M = 0.349 m). Total four operating points were considered. At each operating point, three schemes of guide vanes opening and three schemes of guide vanes closing were investigated. The results show that total head variation is up to 9% during start-stop of the turbine. On the runner blade, the maximum pressure amplitudes are about 14 kPa and 16 kPa from the instantaneous mean value of 121 kPa during rapid start-up and shutdown, respectively, which are about 1.5 times larger than that of the slow start-up and shutdown. Moreover, the maximum pressure fluctuations are given at the blade trailing edge.

中文翻译：

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高水头模型弗朗西斯水轮机启动和关闭过程中瞬态压力变化的实验研究

使用风能和太阳能产生的电力渗透到电网网络，导致电网跳闸，断电和频率下降的几次事件。由于并网连接的水力涡轮机被广泛用于管理电网的关键条件，因此这大大增加了水力涡轮机的重启（星形停止）循环。由于转轮叶片上的压力负载不稳定，每个循环都会产生很大的应力。这项工作研究了启停过程中高压水头（H _P = 377 D _P = 1.78 m）的压力负荷。测量是在比例模型涡轮机上进行的（H _M = 12.5 D _M = 0.349 m）。共考虑了四个工作点。在每个工作点，研究了三种导叶打开方案和三种导叶关闭方案。结果表明，在汽轮机启停过程中，总扬程变化高达9％。在叶轮叶片上，最大压力幅值分别比快速启动和停机期间的瞬时平均值121 kPa分别高约14 kPa和16 kPa，约为慢速启动和停机的1.5倍。 。而且，在叶片后缘处给出最大压力波动。