探讨了水电站过渡过程数值计算中水轮机边界条件基本方程及其迭代算法稳定性问题，从理论上推导出两种迭代算法的收敛判别条件。得到反映水流动能（或惯性）与势能比值的收敛判别变量T，当水流势能占优势时，即T≤1，第一迭代算法收敛;当水流惯性占优势时，即T>1，第二迭代算法收敛。这两个条件互补，从而证明反击式水轮机边界条件是全范围内可求解的。该判别条件已经在实际工程计算中得到验证和运用。

水电站进水口漂浮式拦污排由若干浮箱链接成索状，可简化为柔系平面结构。将水流、风和波浪对拦污排浮箱的作用转化为链节点作用力，然后根据虚功原理导出描述拦污排平衡状态的非线性方程组，并采用迭代方法求得漂浮式拦污排轴线张拉形状和张力数值解。洪江水电站工程实例计算结果表明：拦污排形态和轴向张力分布规律受水流单独或与风、波浪组合作用的影响非常明显，不同运行工况呈现不同的形态，且张力一般呈非均匀分布，岸边支墩反力值大于坝前支墩反力值，张拉形态和张力分布与悬链线理论计算结果差别较大。尤其在不发电泄洪运行工况下，进水口水域主流方向变化显著、流速增大，拦污排将出现非稳定性态，可能产生流体诱发大幅度摆动。

水电站引水发电系统过渡过程是流体、机械、电气、甚至结构相互耦合的复杂的动态过程，现有的将水、机、电分开研究的方法及成果无法满足大型长输水道地下式水电站设计和运行的需要，所以需要开展水电站过渡过程整体性物理模拟。本文作为初步的探讨，着重介绍模型比尺、水机电整体模拟、控制测试以及大波动、小波动和水力干扰等过渡过程的试验结果，并与数值仿真计算结果对比。

根据水电站引水发电系统布置的特点和水电站过渡过程数值计算的实际需要，甩面向对象方法法实现水电站引水发电系统的图形化模拟以图形化物理参数输人。井提出以动态编号方法以及于管线组合为基础的自动编码方法，实现了引水发电系统拓扑关系的自动建立。开发出适合普通术电站设计人员使用的水电站过渡过程可视化计算软件。

With the Thoma's assumption, the critical sectional area for flow stability of the downstream throttled surge tank is derived theoretically. The effects of the velocity head and momentum exchange at the Tee junction between the surge tank riser and the tail water tunnel on the critical sectional area of the downstream tank have been analyzed using the Gardel's head loss formula. The study shows that the velocity head has an unfavorable effect on the water level stability in the downstream surge tank while the effect of the momentum exchange is positive. Two effects counteract. Thus the critical sectional area of a downstream throttled surge tank is close to that of a corresponding simple surge tank. However, if the size and shape of a riser are optimized, the area of the downstream surge tank may be further reduced. It is also demonstrated that a downstream throttled surge tank can reduce electricity loss and meet the requirements of stability easily in large flow oscillations compared to a simple downstream tank.