【作者】 李琪飞；

【导师】 李仁年；

【作者基本信息】 兰州理工大学 ， 流体机械及工程， 2018， 博士

【摘要】 可逆式水泵水轮机是能源互联网实现分布式能源存储和调节的核心装备之一。随着抽水蓄能机组在我国电力系统中所占比重的逐年增加以及单机容量的不断增大,抽水蓄能电站和机组的可靠性对系统的安全运行越来越重要。可逆式水泵水轮机“S”特性区引起的机组运行不稳定问题,已经成为当前可逆式水泵水轮机设计、运行环节中最重要的问题,直接影响可逆式水泵水轮机发电工况空载启动时的稳定性,如果处理不好,甚至会引起整个电力系统的崩溃,带来巨大的经济损失。本研究以某抽水蓄能电站可逆式水泵水轮机为研究对象,依托国内某研究所工程中心水轮机试验平台,针对可逆式水泵水轮机“S”特性与内流诱导机理开展了模型试验研究、全流场三维非定常数值模拟,探讨了非同步导叶(MGV)改善“S”特性及其内流诱导机理,主要研究内容如下。1、开展了可逆式水泵水轮机模型试验研究,阐述了试验台基本系统,进行了试验台综合误差分析,结合抽水蓄能电站参数做了一定计算分析;开展了可逆式水泵水轮机水轮机工况模型试验和水泵工况模型试验,得出模型试验各项指标均符合IEC60193—1999(《水轮机、蓄能泵和水泵水轮机模型验收试验规程》)要求,测试得出的各项性能完全满足设计时给定的保证值要求,测试结果为数值分析计算提供了依据及所需基础参数。2、以模型可逆式水泵水轮机为研究对象,建立了计算模型,进行了网格划分,运用能够有效捕捉近壁区以及远壁区流动特征的SST k-ω湍流模型,进行了可逆式水泵水轮机全流场三维湍流数值模拟。数值模拟结果与模型试验结果对比得到综合特性曲线基本趋势一致,吻合度较高,表明三维全流道非定常数值计算的可信、可靠;针对可逆式水泵水轮机的“S”特性区域特殊流动问题,围绕机组内部流动特征、湍流结构的时空演变机制,着重分析计算了水泵水轮机水轮机工况同步启动过渡过程中的内流特性及其演化过程,得出了“S”特性内流诱导机理,探讨了“S”特性改善的内流控制方法。3、开展了可逆式水泵水轮机模型四象限全特性及“S”区特性试验研究和MGV装置改善可逆式水泵水轮机“S”特性区试验研究,获取了四象限全特性曲线、模型“S”特性曲线、模型全特性曲线、不同导叶开度MGV装置的“S”特性曲线,分析得出低水头空载启动开度区存在不稳定“S”区域;MGV装置可显著改善可逆式水泵水轮机“S”特性。通过数值模拟得到投入MGV装置下,可逆式水泵水轮机“S”特性区单位转速与单位流量的关系曲线,探讨了同步导叶与MGV不同布置方式对“S”特性的影响,得出两对非同步导叶均匀分散对称布置为最优MGV布置方式的结论;同时通过对可逆式水泵水轮机非同步导叶工况下的全流场三维定常和非定常流动分析,得到了可逆式水泵水轮机最优MGV布置工况的内流特性及改善机理,为可逆式水泵水轮机综合水力性能的改善提供参考。更多还原

【Abstract】 In the energy interconnection,reversible pump-turbine is one of the core equipment which plays an important role in distributed energy storage and transition.With the increase of proportion and single capacity,the reliability of the reversible units is important to the safe operation of the system.The operational instability caused by “S” characteristic has become a critical point of design and operation of the reversible pump-turbine,which directly affects the stability of the units and causes the collapse of the electric power systems under the no-load start-up condition.In this study,flow induction mechanism and characteris tics on the “S” working condition of reversible pump-turbine in the pump storage units are investigated with the model test and three-dimensional unsteady numerical simulation.At the same time,the method on improvement of “S” characteristic by MGV(Misaligned Guide Vanes)devices based on internal flow induction mechanism are given.The main contents are described as follows.1.Model tests of reversible pump-turbine are carried out and basic system of the test platform is introduced.Based on the parameters of pumped-storage stations,the comprehensive error and relative calculation are discussed.The indexes of model test are consistent with the standard of IEC 60193-1999(“Hydraulic turbine,storage pump and pump turbine model acceptance test code”).The performance of the test is consistent with the design values.The results of model test provide the reliability verification and basic calculation parameters for the numerical simulation.2.The 3-dimensional physics model and grid are established based on the model.SST k-ω turbulence model is used to simulate the three-dimensional total flow field,which can effectively capture the characteristics of the near wall area and the far-wall flow.The numerical simulation result s of the comprehensive characteristic are consistent well with experiment results,which indicate the reliability of the numerical calculation.Flow-induced mechanism of “S” working condition is revealed by the analysis of flow characteristics and evolution process of turbulence structure under the synchronous guide vane start-up process,based on which,the improvement methods of “S” characteristics are discussed.3.The curves of the four-quadrant full characteristic,“S” characteristic,full characteristic of model and “S” characteristic under MGV device with different opening are obtained by the model test s.Based on the analysis of the curves,the “S” characteristic can be improved by MGV device under different opening in reversible pump turbine under the low head no-load start-up working condition.The relationships between unit speed and unit discharge in the “S” characteristic region are given by the simulation under the MGV device.The effects of synchronous guide vane and MGV with the different arrangement mode on the “S” characteristic are discussed,based on which,the best mode of the MGV device with two pairs of uniformly dispersed symmetrical arrangement are obtained.The flow characteristics and improvement mechanism are given by the three-dimensional unsteady flow simulation under the best arrangement of MGV device,which can provide some references on the improvement of comprehensive hydraulic performance for the reversible pump-turbine.更多还原