水电站调压室托马临界稳定断面公式再认识  

New understanding of Thoma’s formula for critical stable section of surge chamber in hydropower station

作　　者：张健 姚天语[2] 王沁怡 仇为鑫 陈龙 陈胜[1,2] ZHANG Jian;YAO Tianyu;WANG Qinyi;QIU Weixin;CHEN Long;CHEN Sheng(The National Key Laboratory of Water Disaster Prevention,Nanjing 210098,China;College of Water Conservancy and Hydropower Engineering Hohai University,Nanjing 210098,China)

机构地区：[1]水灾害预防全国重点实验室,江苏南京210098 [2]河海大学水利水电学院,江苏南京210098

出　　处：《水利学报》2023年第8期898-909,共12页Journal of Hydraulic Engineering

基　　金：国家自然科学基金项目(51839008,51879087)。

摘　　要：托马临界稳定断面公式通常被认为是含调压室的水电站输水发电系统运行稳定性判别的重要依据。本文首先从理论上论证了刚性水体假设与等出力调节方式下,系统不可能稳定运行;之所以能够得到托马临界稳定断面公式,是由于推导过程中忽略了调压室后压力管道与机组后尾水道的水体惯性,而这恰是导致系统不稳定的关键因素。其次针对实际弹性水体,理论上论证了等出力调节方式下,真实的水力发电系统也不可能稳定运行;同时指出含调压室的水电站输水发电系统稳定性主要取决于水轮机上下游侧的水锤反射系数;无论是调压室前引水道还是调压室后的压力管道与尾水道,管道内的摩阻均有利于稳定,调压室面积大小对稳定影响相对较小;等出力调节模式下,无论是采用刚性水体假设还是针对实际弹性水体,含调压室的水电站输水发电系统一定是不稳定的,一个不稳定的系统不可能存在稳定断面,托马临界稳定断面在理论上是不成立的。Thoma’s formula for critical stable section is generally regarded as a significant basis for judging the operational stability of the water conveyance and power generation system of hydropower station with surge chamber.This present study firstly theoretically demonstrates the system cannot be stable with both the rigid body assumption and constant output regulation.The Thoma’s formula for critical stable section could be obtained because the water inertia of the penstocks and the tailrace tunnel is neglected in the derivation,which is the key factor to the system instability.Furthermore,it is proved theoretically that the hydraulic system may not run stably under the constant output regulation mode for the actual elastic water.Meanwhile,the stability of the water conveyance and power generation system of the hydropower station with surge chamber mainly depends on the water hammer reflection coefficient of the upstream and downstream side of the turbine.The friction of the diversion tunnel,penstock and tailrace tunnel are all beneficial to stability,while the size of the surge chamber has relatively little effect on stability.Under constant output regulation mode,the water conveyance and power generation system of the hydropower station with surge chamber must be unstable no matter adopting the rigid water hypothesis or actual elastic water.An unstable system could not exist stable section,and Thoma’s formula for critical stable section is not valid in theory.

关 键 词：水电站 调压室 稳定性 托马公式 水锤反射系数 

分 类 号：TV732.5[水利工程—水利水电工程]