特殊工况下抽水蓄能电站系统参数过渡过程分析

在抽水蓄能电站水力过渡过程数值模拟中,由于水泵-水轮机全特性曲线所具有的特殊性,使得尾水管进口最小压力在机组相继甩负荷工况下会大幅度降低,且时常会成为控制值。以一维刚性水锤及弹性水锤的特征线方法(MOC)为理论基础,结合某"一洞两机"布置形式的抽水蓄能电站工程实例,对该电站相继甩负荷工况下引水隧洞洞径及尾水岔管相对位置对过渡过程的影响进行了数值模拟。结果表明:在设置尾水调压室的情况下,拟通过改变引水隧洞洞径来调节尾水进口最小压力的措施是不经济的,引水隧洞的面积只需使其中的水流能够保持经济流速即可;在满足工程布置的前提下,应尽量减小尾水支管的长度,以保证输水发电系统的安全运行。

Analysis of transition process of system parameters of pumped storage power station under special working condition

In numerical simulation of hydraulic transient process of pumped storage power station, due to the special nature of four-quadrant characteristic curve of pump-turbine, the minimum pressure at the inlet of the draft tube will be greatly reduced under the condition of successive load rejection and often become a control value. Based on the method of characteristics ( MOC) of one dimensional rigid water hammer and elastic water hammer, a pumped storage power station that adopts the scheme of“two turbines sharing one diversion tunnel” was taken as an example, and the influence of diameter of its diversion tunnel and the rela-tive position of its tail water bifurcated pipe on transition process under successive load rejection were numerically simulated. The results show:with the arrangement of tailrace surge tank, it is not economical to adjust the minimum pressure at the inlet of the draft tube by changing the tunnel diameter;The tunnel area is optimal when it keeps the flow rate at an economical level;Under the premise of meeting the requirements of engineering layout, the length of the tail water bifurcated pipe should be reduced as much as possible to ensure the safe operation of water conveyance and power generation system.