【作者】 杨彪；

【导师】 刘昌玉；

【作者基本信息】 华中科技大学 ， 水利工程， 2022， 硕士

【摘要】 随着我国“3060”目标的提出,出力具有较强不确定性的风电和光电的并网装机容量快速增加,需要抽水蓄能机组通过更加频繁的工况转换来满足电网的调节需求。但机组在水轮机开机、甩负荷等过程中易进入S特性区域,可能会出现水击压力过大和同期并网困难等问题。且目前的水泵水轮机朝着大容量、高扬程方向发展,其驼峰区和S特性区的不稳定特性更加突出,严重威胁着机组的安全与稳定。因此,本文将针对改善水泵水轮机S特性影响的措施开展研究。首先,建立了带有非同步导叶(misaligned guide vanes,MGV)装置和球阀的水泵水轮机调速系统模型,并通过与机组实测数据对比的方式验证了其准确性;提出了适用于投入MGV装置情况的水轮机调速系统数值仿真算法。其次,针对水泵水轮机在紧急停机时水击压力过大的问题,分别投入了 MGV装置和球阀用于改善蜗壳进口和尾水管进口处的压力;在甩负荷工况下,分别提出了 MGV装置和球阀参与调节的控制规律,并通过仿真试验验证了所提措施对机组运行品质的改善效果;在水轮机开机工况下,分别采用了 MGV装置和球阀来改善机组的空载稳定性,探究了 MGV装置的较优布置方式和球阀的较优开度。最后,在上述工况下,基于投入MGV装置或球阀后的机组过流特性,分析了 MGV装置和球阀改善机组运行品质的机理。本文采用了 MGV装置和球阀改善水泵水轮机调速系统的调节品质,实现机组在S特性区内运行的控制优化。仿真结果表明,MGV装置和球阀都能显著提升机组在上述工况下的运行品质,能有效减小蜗壳进口最大压力、提升尾水管进口最小压力和缩短同期时间;其中对称加装两对MGV装置、预开启至0.15的布置方案开机效果较好;球阀提前开启至0.40的开机方案最优。MGV装置和球阀都能显著地改善机组在S特性区内的运行品质,其中球阀的改善效果更好。更多还原

【Abstract】 With the proposal of China’s "3060" goal,the grid-connected installed capacity of wind and photovoltaic which with strong output uncertainty has increased rapidly,and pumped storage units are required to meet the adjustment needs of the power grid through more frequent condition conversions.However,the units are easy to enter the S-shaped area during turbine start-up and load rejection,which may lead to problems such as excessive water hammer pressure and difficult synchronization.At present,the pump turbine is developing towards large capacity and high head,and the instability characteristics of hump area and S-shaped area are more prominent,which seriously threatens the unit’s safety and stability.Therefore,this paper studies the measures to improve the influence of S characteristics of pump turbine.Firstly,a model of pump-turbine governing system with misaligned guide vanes(MGV)devices and ball valve is established,and its accuracy is verified by comparing with the measured data of the unit.A numerical simulation algorithm of turbine governing system suitable for MGV devices is proposed.Secondly,in order to improve the problem of excessive water hammer pressure of pump turbine during emergency shutdowns,MGV devices and ball valve are respectively used to improve the inlet pressure of volute and draft tube.Under the load rejection conditions,the control laws of the MGV devices and the ball valve participating in regulation are proposed respectively,and the improvement effects of the proposed measures on the unit’s operation quality is verified by simulation experiments.Under start-up conditions,the MGV devices and the ball valve are adopted to improve the no-load stability of the unit,and the optimal layout of the MGV devices and the optimal opening of the ball valve are explored.Finally,under the above conditions,based on the unit’s flow characteristics after putting MGV devices or ball valve into operation,the mechanism of MGV devices and ball valve to improve the unit’s operation quality is analyzed.In this paper,the MGV devices and ball valve are respectively used to improve the regulation quality of the pump-turbine governing system and realize the control optimization when the unit operates in S-shaped area.The simulation results show that both the MGV devices and the ball valve can significantly improve the operating quality of the unit under the above conditions,reduce the maximum pressure at the volute inlet,raise the minimum pressure at the draft tube inlet and shorten the synchronization time.Among them,the layout schemes of symmetrically installing two pairs of MGV devices and pre opening to 0.15 has better start-up effect.The best start-up scheme is to open the ball valve to 0.40 in advance.Both MGV devices and ball valve can significantly improve the operation quality of the unit in the S-shaped area,and the improvement effect of ball valve is better.更多还原