定-变速抽水蓄能机组调相-发电过渡过程动态特性研究

可变速抽水蓄能作为一种较新的机组形式，在参与电网调相调频、功率调节等方面相对传统定速机组具有独特优势。调相-发电过程作为抽水蓄能机组应对风光等间歇性可再生能源波动的典型过渡过程，对过流部件压力波动及机组运行稳定性有显著影响。目前抽水蓄能电站中广泛采用的一管多机布置形式存在水力干扰现象，一台机组的工况变化会影响其他机组的运行。同时，变速机组的引入会使机组展现出与传统机组不同的水力动态特性。为深入探究调相-发电过渡过程中不同机组布置形式下复杂管道系统的水力动态特性及相关稳定性问题，结合工程数据，基于特征线法和S函数等方法构建三种不同机组组合形式下一管双机抽水蓄能机组模型。针对不同机组布置形式，分别探究不同动作间隔下机组的蜗壳压力、尾水管压力及调压井流量等水力因素的动态特性及其对蓄能机组稳定性的影响。定量分析结果表明：在调相-发电工况下，工作水头及蜗壳压力先下降后上升，尾水压力、下游调压井水位及流量呈现正弦式衰减振荡；3种组合形式中定速-变速机组组合稳定性效果最佳，变速-变速组合的水力波动最大。本研究为定、变速组合的抽水蓄能电站安全稳定运行提供一定的理论依据。

Study on dynamic characteristics of phase modulation-generation transition process of fixed-speed and variable-speed pumped-storage units

Variable-speed pumped storage, as a relatively new form of unit, has unique advantages over traditional fixed-speed units in participating grid phase regulation and power regulation. As a typical transition process for hydropower units to cope with fluctuations in intermittent renewable energy sources such as wind power and photovoltaic, phase regulation-generation has a significant impact on pressure fluctuations in flow-passing parts and the stability of unit. The scheme of a single penstock feeding multiple pump turbines widely used in current pumped storage power plants has the phenomenon of hydraulic interference, and the change of one unit''s working condition will affect the operation of other units. Meanwhile, using the variable speed units may cause the hydraulic dynamic characteristics of the units different from those of the traditional units. To deeply explore the hydraulic dynamic characteristics and related stability issues of complex pipeline systems under different unit arrangements in the transition process of phase modulation-power generation, combined with engineering data, the model of one pipe and two pumped storage units under three different unit combinations was built based on the methods of characteristic line and S-function. The dynamic characteristics of hydraulic factors, such as volute pressure, tail pipe pressure as well as surge tank flow rate, and their effects on the stability of the storage units were studied separately for different unit arrangements with different operation intervals. The quantitative analysis results show that under the phase modulation-generation condition, the working head and volute pressure decreases first and then rises, and the tail water pressure, the water level and flow rate of the downstream surge well show sinusoidal damping oscillation. The stability effect of the fixed-variable-speed unit combination is the best, and the double variable-speed combination form has the largest hydraulic fluctuation. This study provides certain theoretical basis for the safe and stable operation of fixed and variable-speed pumped storage power plants.