超长引水隧洞水电站水道-调压室非线性水力耦合特性与优化研究

The hydropower station with super long headrace tunnel has the following features: the flow inertia and head loss in the water conveyance and the amplitude of water level oscillation in the surge tank are extremely large, the hydraulic characteristics of the water conveyance - surge tank system are complicated and of strong nonlinearity. As a result, the characteristics of transient process of the hydropower station with super long headrace tunnel are obviously different from those of the hydropower station with short headrace tunnel. The hydraulic design optimization theories and methods for the hydropower station with short headrace tunnel cannot be indiscriminately applied into the hydropower station with super long headrace tunnel. In this project, within the scope of dynamic response and stability of hydro-turbine governing system, the research on the nonlinear hydraulic coupling characteristics and optimization of water conveyance - surge tank system is carried out based on the unique transient process and essential nonlinear hydraulic characteristics of the hydropower station with super long headrace tunnel. Firstly, the complicated and strong nonlinear hydraulic coupling characteristics of the water conveyance - surge tank system are analytically investigated. Then, the transient characteristics and control of the hydro-turbine governing system under the nonlinear hydraulic coupling are analyzed. Finally, the hydraulic design optimization theories and methods for the water conveyance - surge tank system of hydropower station with super long headrace tunnel are comprehensively studied. The research purpose is: establishing the nonlinear hydraulic coupling mathematical model of water conveyance - surge tank system for hydropower station with super long headrace tunnel, revealing the effect mechanism of the nonlinear hydraulic characteristics on the transient characteristics of the hydro-turbine governing system, proposing the critical discriminant conditions for the length and flow inertia of headrace tunnel based on the stability and regulation quality, establishing the hydraulic design optimization theories and methods for the water conveyance - surge tank system based on the nonlinear hydraulic coupling. The research results would lay the foundation of applied research and provide the support of key science and technology for the development of hydropower station with super long headrace tunnel.

超长引水隧洞水电站具有水道水流惯性和水头损失巨大、调压室涌浪幅度巨大以及水道-调压室水力特性复杂强非线性的特点，使其过渡过程明显有别于短引水隧洞水电站，无法套用后者的引水发电系统水力优化理论与方法。本项目在水轮机调节系统动态响应与稳定性范畴内，基于超长引水隧洞水电站的独特过渡过程与非线性水力本质特性，开展水道-调压室非线性水力耦合特性与优化研究。通过解析水道-调压室复杂强非线性水力耦合特性，分析非线性水力耦合下的水轮机调节系统动态响应与稳定性，探究超长引水隧洞水电站水道-调压室系统水力设计优化理论与方法。力争建立超长引水隧洞水电站水道-调压室非线性水力耦合模型，揭示非线性水力特性对水轮机调节系统暂态特性的作用机理，提出基于稳定性和调节品质的引水隧洞长度与水流惯性临界判别条件，建立基于非线性水力耦合的水道-调压室水力设计优化理论与方法，为超长引水隧洞水电站的建设运行奠定科学基础与技术支撑。

超长引水隧洞水电站是水电能源开发的一种重要型式，其独特的过渡过程特性使得研究并提出完整的适用于超长引水隧洞水电站的水道-调压室系统水力设计优化理论与技术体系十分必要。本项目基于超长引水隧洞水电站的独特过渡过程与非线性水力本质特性，开展水道-调压室非线性水力耦合特性与优化研究。建立了基于水道-调压室非线性水力耦合的超长引水隧洞水电站数学模型，实现了水道-调压室系统复杂强非线性特性的耦合，探明了水道非线性水头损失与调压室阻抗损失对水电站系统动态响应及稳定性的影响，揭示了水道-调压室非线性水力耦合作用对过渡过程中系统能量耗散与转化的影响。揭示了一洞双机超长引水隧洞水轮机调节系统稳定性，阐明了基于水道-调压室非线性水力耦合的超长引水隧洞水电站一次调频动态特性，提出了超长引水隧洞水电站水轮机调节系统鲁棒控制策略，有效地调节了调压室水位波动。推导了基于水轮机调节系统稳定性考虑压力管道水头损失非线性的调压室设置条件，揭示了调压室设置条件的特性与适用性，推导了考虑引水隧洞水头损失和机组等出力非线性的调压室临界稳定断面公式，该临界稳定断面公式可以表示为放大系数乘以托马断面。研究成果发展了水电站水道-调压室水力设计优化理论与技术体系，对于指导水道-调压室水力优化和机组安全稳定运行控制有重要价值与意义，为超长引水隧洞水电站安全经济建设与稳定高效运行提供了理论基础和技术支撑。