水泵水轮机调节系统稳态与典型暂态过程稳定性分析

发布时间：2019-01-09 12:24

【摘要】：抽水蓄能电站可将电网负荷较低时的多余电能,转化为电网高峰期的高价值电能,同时还具有调频调相和事故备用等多种功能,亦可提高风电、火电和核电的利用效率,在电力系统中发挥着越来越重要的作用。水泵水轮机调节系统作为抽水蓄能电站的核心,研究其运行稳定性对维持电站安全、稳定和经济运行具有重要作用。以往对抽水蓄能机组的研究主要集中于水泵水轮机,很少将其纳入整个调节系统的框架下,也无法揭示其深入的动力学演化机理。本文从系统工程学角度出发,对调节系统稳态和两种典型暂态过程进行了微分数学建模和稳定性分析,借助分岔图、时域图和相轨迹图进行数值模拟,验证了理论结果的正确性。论文的主要研究内容及结论如下:(1)考虑压力管道水力摩阻和弹性水击效应,建立了水泵水轮机调节系统的稳态模型;推导出泵工况下传递系数的表达式,结合潘家口抽水蓄能电站的系统参数,计算出泵额定工况下传递系数值;运用稳定性定理,借助MATLAB工具计算出系统PID调节参数的稳定域,通过数值模拟验证了所得结果的正确性;对比分析了有无水力摩阻对系统稳定域的影响,结果表明:水力摩阻对维持系统稳定运行是有利的,同时,研究并给出几种参数取值不同时稳定域的变化规律;最后对比分析了水轮机和水泵工况下的稳定域范围,结果显示,前者的调节参数稳定域通常较后者要小。(2)结合实际抽水蓄能电站泵工况断电的运行曲线,截取若干时间点计算出相应的传递系数的值,得到传递系数随时间变化的表达式,从而获得调节系统泵工况断电暂态过程的动态数学模型,通过数值模拟分析了不同时间点系统的稳定性,结果表明导叶关闭速率对调节系统的稳定性具有重要影响。其次,做出稳定域随时间变化的三维图和二维图,结果显示:在该暂态过程中,稳定域随着时间的增加先减小后增大。并得到了稳定域范围最小的时刻,即最不利时间点。(3)针对上游有调压室的水泵水轮机调节系统甩负荷导叶拒动暂态过程建立了微分数学模型,然后推导出水泵水轮机的飞逸稳定性条件,其特性曲线在飞逸工况点处的斜率是决定飞逸稳定性的重要因素。最后,结合模型全特性曲线,得到水轮机、水轮机制动和反水泵三种工况下系统关于相对转速的动态模型,通过分岔图研究了系统反“S”区的稳定性,结果表明:稳定运行区主要集中在水轮机和反水泵工况,不稳定区主要集中在制动工况。
[Abstract]:Pumped-storage power station can convert excess electric energy from low load to high-value electric energy during peak period of power grid, at the same time, it also has many functions such as frequency modulation and phase modulation and accident standby, and can also improve the utilization efficiency of wind power, thermal power and nuclear power. It plays a more and more important role in power system. As the core of pumped storage power station, pump turbine regulation system plays an important role in maintaining the safety, stability and economic operation of the power station. In the past, the research on pumped-storage units was mainly focused on pump turbines, and it was rarely incorporated into the framework of the whole governing system, nor could it reveal the mechanism of its dynamic evolution. In this paper, from the point of view of system engineering, differential mathematical modeling and stability analysis of steady state and two typical transient processes of regulating system are carried out, and numerical simulation is carried out by means of bifurcation diagram, time domain diagram and phase trajectory diagram. The correctness of the theoretical results is verified. The main research contents and conclusions are as follows: (1) considering hydraulic friction and elastic water hammer effect of pressure pipeline, the steady state model of pump turbine regulating system is established; The expression of transfer coefficient under pump condition is deduced, and the transfer coefficient under rated condition is calculated with the system parameters of Panjiakou Pumped-storage Power Station. By using the stability theorem and the MATLAB tool, the stability region of the system PID adjustment parameters is calculated, and the correctness of the obtained results is verified by numerical simulation. The effects of hydraulic friction on the stability region of the system are compared and analyzed. The results show that the hydraulic friction is beneficial to maintain the stable operation of the system. At the same time, the variation of several parameters in different stability regions is studied and given. Finally, the stability range of turbine and pump are compared and analyzed. The results show that the stability range of the former is usually smaller than that of the latter. (2) combined with the operation curve of pump failure in actual pumped storage power station, By intercepting some time points to calculate the corresponding transfer coefficient, the expression of the transfer coefficient varying with time is obtained, and the dynamic mathematical model of the transient process of pump power failure in regulating system is obtained. The stability of the system at different time points is analyzed by numerical simulation. The results show that the closing rate of the guide vane has an important effect on the stability of the regulating system. Secondly, the three dimensional and two dimensional diagrams of the stability region varying with time are made. The results show that the stability region decreases first and then increases with the increase of time in the transient process. At the same time, the minimum time in the stability region is obtained, that is, the most unfavorable time point. (3) the differential mathematical model is established for the transient process of load rejection and guide vane rejection in a pump turbine governing system with an upstream surge chamber. Then the flight stability condition of water pump turbine is deduced. The slope of the characteristic curve at the point of flight escape is an important factor to determine the flight escape stability. Finally, combined with the full characteristic curve of the model, the dynamic model of the relative rotational speed of the system under three working conditions of turbine, turbine braking and backwater pump is obtained, and the stability of the inverse "S" region of the system is studied by bifurcation diagram. The results show that the stable operation zone is mainly concentrated in the turbine and reverse pump conditions, and the unstable zone is mainly concentrated in the braking condition.
【学位授予单位】：西北农林科技大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV743;TV734

【相似文献】